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Noninvasive Fractional Flow Reserve by Coronary Computed Tomographic Angiography

Policy Number: MP-635

Effective for dates of service on or after March 1, 2019, refer to: PET, MRI, MRA, CT, CTA/CCTA (Advanced Imaging Guidelines)

 Latest Review:  Date: May 2018

Category: Radiology                                                             

Policy Grade:  C

DESCRIPTION OF PROCEDURE OR SERVICE:

Invasive coronary angiography (ICA) is clinically useful in patients with stable ischemic heart disease (SIHD) when there is coronary artery obstruction that may benefit from revascularization. However, many individuals currently undergoing ICA will not benefit from revascularization. Therefore, if there are noninvasive alternatives to guide decisions about the use of ICA to spare individuals from undergoing unnecessary ICA, there is potential to improve health outcomes. Using noninvasive measurement of fractional flow reserve as part of a noninvasive imaging strategy prior to ICA may be beneficial to avoid the need for ICA.

 

Stable Ischemic Heart Disease

Coronary artery disease (CAD) is a significant cause of morbidity and mortality and various epidemiologic risk factors have been well studied. Evaluation of obstructive CAD involves quantifying arterial stenoses to determine whether significant narrowing is present. Lesions with stenosis more than 50% to 70% in diameter accompanied by symptoms are generally considered significant. It has been suggested that coronary computed tomography angiography (CCTA) or other noninvasive functional cardiac testing may help rule out CAD and avoid invasive coronary angiography in patients with a low clinical likelihood of significant CAD. However, invasive coronary angiographies (ICAs) are frequently unnecessary in patients with suspected stable ischemic heart disease (SIHD), as evidenced by low diagnostic yields for significant obstructive CAD. For example, from a sample of over 132,000 ICAs, Patel et al (2010) found 48.8% of elective ICAs performed in patients with stable angina did not detect obstructive CAD (left main stenosis ≥50% or ≥70% in a major epicardial or branch >2.0 mm in diameter). ICA is clinically useful when patients with stable angina have failed optimal medical therapy and may benefit from revascularization. A noninvasive imaging test, performed prior to ICA as a gatekeeper, that can distinguish candidates who may benefit from early revascularization (e.g., patients with unprotected left main stenosis ≥50% or hemodynamically significant disease) from those unlikely to benefit could avoid unnecessary invasive procedures and their potential adverse consequences. Moreover, for the large majority of patients with SIHD, revascularization offers no survival advantage over medical therapy; there are few who might benefit from ICA if they have not first failed optimal medical therapy.

 

Clinical Risk Prediction

The 2012 collaborative medical association guidelines for the diagnosis and management of patients with stable heart disease list several class I recommendations on use of noninvasive testing in patients with suspected SIHD. A class I recommendation indicates that a test should be performed. In general, patients with at least intermediate risk (10%-90% risk by standard risk prediction instruments) are recommended to have some type of test, the choice depending on interpretability of the electrocardiogram, capacity to exercise, and presence of comorbidity.

Clinical prediction scores or models have been developed to help estimate the pretest probability of CAD in individuals with stable chest pain. A commonly cited clinical prediction model based on age, sex, and type of pain symptoms, originally developed by Diamond and Forrester (1979), has been further studied and extended in a report by Genders et al (2011) and compared to the Duke Clinical Score by Wasfy et al (2012). Versteylen et al (2011) published a comparison of clinical prediction results for the Diamond and Forrester model, the Framingham risk score, the PROCAM risk score, and the SCORE risk estimation model. Another model has been published by Min et al (2015) and an online calculator developed by a CAD consortium.

 

Gatekeepers to ICA

Imposing an effective noninvasive gatekeeper strategy with one or more tests before planned ICA to avoid unnecessary procedures is compelling. The most important characteristic of a gatekeeper test is its ability to accurately identify and exclude clinically insignificant disease where revascularization would offer no potential benefit. From a diagnostic perspective, an optimal strategy would result in few false-negative tests while avoiding an excessive false-positive rate—it would provide a low posttest probability of significant disease. Such a test would then have a small and precise negative likelihood ratio and high negative predictive value. An effective gatekeeper would decrease the rate of ICA while increasing the diagnostic yield (defined by the presence of obstructive CAD on ICA). At the same time, there should be no increase in major adverse cardiac events. A clinically useful strategy would satisfy these diagnostic performance characteristics and impact the outcomes of interest. Various tests have been proposed as potentially appropriate for a gatekeeper function prior to planned ICA, including CCTA, magnetic resonance imaging, single-photon emission computed tomography, positron emission tomography, and stress echocardiography. More recently, adding noninvasive measurement of fractional flow reserve (FFR) using CCTA has been suggested, combining functional and anatomic information.

 

Fractional Flow Reserve

Invasively measured fractional flow reserve (FFR) evaluates the severity of ischemia caused by coronary artery obstructions and can predict when revascularization is beneficial. FFR has not been used as a diagnostic test for ischemic heart disease, but as a test to evaluate the degree of ischemia caused by a stenosis.

 

Invasive FFR is rarely used in the United States to guide percutaneous coronary intervention (PCI). For example, using the National Inpatient Sample, Pothineni et al (2016) reported that 201,705 PCIs were performed in 2012, but just 21,365 FFR procedures. Assuming the intention of FFR is to guide PCI, it would represent just 4.3% of PCI procedures. Whether noninvasively obtained FFR will influence decisions concerning ICA, over and above anatomic considerations, is therefore important to empirically establish.

 

Randomized controlled trials and observational studies have demonstrated that FFR-guided revascularization can improve cardiovascular outcomes, reduce revascularizations, and decrease costs. For example, the Fractional Flow Reserve versus Angiography for Multivessel Evaluation (FAME) trial randomized 1,005 patients with multivessel disease and planned percutaneous coronary intervention (PCI). At one year, compared with PCI guided by angiography alone, FFR-guided PCI reduced the number of stents placed by approximately 30%—followed by lower rates (13.2% vs 18.3%) of major cardiovascular adverse events (myocardial infarction, death, repeat revascularization) and at a lower cost. The clinical benefit persisted through two years, although by five years events rates were similar between groups.

 

European guidelines (2013) for stable coronary artery disease recommend FFR be used “to identify hemodynamically relevant coronary lesion(s) when evidence of ischaemia is not available” (class Ia), and “[r]evascularization of stenoses with FFR <0.80 is recommended in patients with angina symptoms or a positive stress test”. Guidelines (2014) also recommend using “FFR to identify haemodynamically relevant coronary lesion(s) in stable patients when evidence of ischaemia is not available” (class Ia recommendation). U.S. guidelines (2012) state that an FFR of 0.80 or less provides level Ia evidence for revascularization for “significant stenoses amenable to revascularization and unacceptable angina despite guideline directed medical therapy.” In addition, the importance of FFR in decision making appears prominently in the 2017 appropriate use criteria for coronary revascularization in patients with SIHD.

 

Measuring FFR during invasive coronary angiography (ICA) requires first passing a pressure-sensing guidewire across a stenosis. Coronary hyperemia (increased blood flow) is then induced and pressures distal and proximal to the stenosis are used to calculate flow across it. FFR is the ratio of flow in the presence of a stenosis to flow in its absence. FFR levels less than 0.75 to 0.80 are considered to represent significant ischemia while those 0.94 to 1.0 normal. Measurement is valid in the presence of serial stenoses, is unaffected by collateral blood flow, and reproducibility high. Potential complications include adverse events related to catheter use such as vessel wall damage (dissection); the time required to obtain FFR during a typical ICA is less than 10 minutes.

 

FFR using CCTA requires at least 64-slice CCTA and cannot be calculated when images lack sufficient quality (11% to 13% in recent studies), e.g., in obese individuals (e.g., body mass index, >35 kg/m2). The presence of dense arterial calcification or an intracoronary stent can produce significant beam-hardening artifacts and may preclude satisfactory imaging. The presence of an uncontrolled rapid heart rate or arrhythmia hinders the ability to obtain diagnostically satisfactory images. Evaluation of the distal coronary arteries is generally more difficult than visualization of the proximal and mid-segment coronary arteries due to greater cardiac motion and the smaller caliber of coronary vessels in distal locations.

 

Noninvasive FFR Measurement

FFR can be modeled noninvasively using images obtained during CCTA- so-called FFR using CCTA (FFR-CT; HeartFlow software termed FFRCT; Siemens cFFR) using routinely collected CCTA imaging data. The process involves constructing a digital model of coronary anatomy and calculating FFR across the entire vascular tree using computational fluid dynamics. FFR-CT can also be used for “virtual stenting” to simulate how stent placement would be predicted to improve vessel flow.

 

Only HeartFlow FFRCT software has been cleared by the U.S. Food and Drug Administration (FDA). Imaging analyses require transmitting data to a central location for analysis, taking 1 to 3 days to complete. Other prototype software is workstation-based with onsite analyses.

 

POLICY:

Effective for dates of service on or after March 1, 2019:

Refer to PET, MRI, MRA, CT, CT/CCTA Advanced Imaging Guidelines

 

Effective for dates of service on and after August 14, 2017 and prior to March 1, 2019:

The use of noninvasive fractional flow reserve* following a positive coronary computed tomography angiography may be considered medically necessary when used to guide decisions about the use of invasive coronary angiography in patients with stable chest pain at intermediate risk of coronary artery disease (i.e. suspected or presumed stable ischemic heart disease).

 

The use of noninvasive fractional flow reserve is considered not medically necessary and investigational when the criteria outlined above is not met.

 

 

*NOTE: Fractional flow reserve using coronary computed tomography angiography requires at least 64-slice coronary computed tomography angiography and cannot be calculated when images lack sufficient quality (HeartFlow, 2013) (11% to 13% in recent studies; Koo et al, 2011; Min et al, 2012; Nakazato et al, 2013; Nørgaard et al, 2014), e.g., in obese individuals (e.g., body mass index, >35 kg/m2). The presence of dense arterial calcification or an intracoronary stent can produce significant beam-hardening artifacts and may preclude satisfactory imaging. The presence of an uncontrolled rapid heart rate or arrhythmia hinders the ability to obtain diagnostically satisfactory images. Evaluation of the distal coronary arteries is generally more difficult than visualization of the proximal and mid-segment coronary arteries due to greater cardiac motion and the smaller caliber of coronary vessels in distal locations.

 

 

Effective for dates of service prior to August 14, 2017:

The use of fractional flow reserve using coronary computed tomographic angiography preceding invasive coronary angiography in patients with suspected stable ischemic heart disease is considered not medically necessary and investigational.

 

 

KEY POINTS:

The most recent literature review was updated through March 6, 2018.

Evidence reviews assess whether a medical test is clinically useful. A useful test provides information to make a clinical management decision that improves the net health outcome. That is, the balance of benefits and harms is better when the test is used to manage the condition than when another test or no test is used to manage the condition.

The first step in assessing a medical test is to formulate the clinical context and purpose of the test. The test must be technically reliable, clinically valid, and clinically useful for that purpose. Evidence reviews assess the evidence on whether a test is clinically valid and clinically useful. Technical reliability is outside the scope of these reviews, and credible information on technical reliability is available from other sources.

CCTA with Selective Noninvasive FFR

Clinical Context and Test Purpose

The purpose of selective noninvasive fractional flow reserve using coronary computed tomography angiography (FFR-CT) in patients with stable chest pain who have suspected SIHD and who are being considered for ICA is to select patients who may be managed safely with observation only, instead of undergoing ICA in the short term.

The question addressed in this evidence review is: Does noninvasive FFR-CT guide decisions to use or not use ICA in patients with stable chest pain or suspected SIHD?

The following PICOTS were used to select literature to inform this review.

Patients

The population of interest includes patients with stable chest pain at intermediate risk of CAD (i.e., with suspected or presumed SIHD) who are being considered for ICA. Patients may have undergone prior noninvasive testing and been treated for presumed stable angina.

Interventions

The intervention of interest is CCTA with selective FFR-CT when CCTA shows evidence of coronary artery stenosis.

Comparators

The comparator of interest is CCTA may be performed alone without FFR-CT. Individuals may proceed directly to ICA. Conventional noninvasive imaging tests providing functional information, including myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT), stress echocardiography (SECHO), and cardiac positron emission tomography (PET), may be used prior to ICA. Cardiovascular magnetic resonance imaging (MRI) is also an option.

Outcomes

The final outcomes of interest include ICA rates, ICA without obstructive CAD, major adverse cardiovascular events (MACE), and adverse events attributed to testing and treatment.

The intermediate outcome of interest is the ability of the test to distinguish clinically significant CAD for which revascularization may provide benefit.

Timing

Rates of ICA and treatment-related morbidity are typically short-term (e.g. ≤3 months). In addition, rates of subsequent ICA, treatment-related morbidity, MACE, quality of life, and resource utilization ascertained over a period of 1 to 3 years are also of interest.

Setting

The setting is a general cardiology practice for patients undergoing nonemergent chest pain evaluation.

Technically Reliable

Assessment of technical reliability focuses on specific tests and operators and requires review of unpublished and often proprietary information. Review of specific tests, operators, and unpublished data are outside the scope of this evidence review and alternative sources exist. This evidence review focuses on the clinical validity and clinical utility.

Clinically Valid

A test must detect the presence or absence of a condition, the risk of developing a condition in the future, or treatment response (beneficial or adverse).

Studies Included in FFR-CT Systematic Reviews: Per-Patient Diagnostic Accuracy

Twenty-six studies have contributed patient level results to a 2015 meta-analyses by Takx et al that examined five non-FFR-CT imaging modalities (see Table 1). Five studies contributed results to two meta-analyses, Wu et al (2016) and Danad et al (2017), evaluating the diagnostic accuracy of FFR-CT using patients as the unit of analysis. Only the FDA-cleared HeartFlow software has been evaluated prospectively across multiple sites. Two small retrospective studies have reported per-patient performance characteristics for the prototype Siemens workstation-based software. The three HeartFlow FFRCT studies used successive software versions with reported improvement in specificity (from 54% to 79%) between versions 1.2 and 1.4. The NXT Trial formed the basis for FDA clearance, and was conducted at 11 sites in eight countries (Canada, EU, Asia). Although not examined in the two included meta-analyses, subgroup analyses suggested little variation in results by sex and age. Effectively, the entirety of the data was obtained in patients of white or Asian decent; almost all patients were appropriate for testing according to FDA clearance.

Danad et al

Danad et al (2017) included 23 studies published between January 2002 and February 2015 evaluating diagnostic performance of cardiac computed tomography angiography (CCTA), FFR-CT, single-photon emission computed tomography (SPECT), stress echocardiography (SECHO), magnetic resonance imaging (MRI), or ICA compared with an invasive FFR reference standard.   The three included FFR-CT studies used the HeartFlow software and had performed FFR in at least 75% of patients. A cutoff of 0.75 defined significant stenosis in eight (32%) studies and in the remainder 0.80 (current standard used in all FFR-CT studies). Per-patient and per-vessel meta-analyses were performed. Study quality was assessed using QUADAS-2; no significant biases were identified in FFR-CT studies but a high risk of biased patient selection was judged in ten (43.4%) other studies. HeartFlow funded publication Open Access; one author was a consultant to, and another a cofounder of, HeartFlow.

On the patient level, MRI had the highest combined sensitivity (90%; 95% CI, 75% to 97%) and specificity (94%; 95% CI, 79% to 99%) for invasive FFR, but were estimated from only two studies (70 patients). FFR-CT had similar sensitivity (90%; 95% CI, 85% to 93%), but lower specificity (71%; 95% CI, 65% to 75%), and accordingly a lower positive likelihood ratio (3.34; 95% CI, 1.78 to 6.25) than MRI (10.31; 95% CI, 3.14 to 33.9). The negative likelihood ratios were low (lower is better) for both FFR-CT (0.16; 95% CI, 0.11 to 0.23) and MRI (0.12; 95% CI, 0.05 to 0.30); however, the confidence interval is more narrow for FFR-CT due to larger sample for FFR-CT. CCTA had a slightly higher negative likelihood ratio (0.22; 95% CI, 0.10 to 0.50). Results for the per-vessel area under the summary receiver operating characteristic curve were similar except for CCTA where per-patient results were considerably worse (e.g., C statistic of 0.57 vs. 0.85). Reviewers noted heterogeneity in many estimates (e.g., CCTA sensitivity, I2=80%). Finally, pooled results for some imaging tests included few studies.

Wu et al

Wu et al (2016) identified seven studies (833 patients, 1,377 vessels) comparing FFR-CT with invasively measured FFR from searches of PubMed, Cochrane, EMBASE, Medion, and meeting abstracts through January 2016. Studies included patients with established or suspected stable ischemic heart disease (SIHD). In addition to the three FFR-CT studies pooled by Danad et al, one additional study using HeartFlow technique (44 patients; 48 vessels) and 3 additional studies (180 patients; 279 vessels) using Siemens cFFR software (not FDA approved or cleared) were identified. An invasive FFR cutoff of 0.80 was the reference standard in all studies. Per-patient (reported in five studies) and per-vessel results were pooled and reported in Table 1. All studies were rated at low risk of bias and without applicability concerns using the QUADAS-2 tool. Appropriate bivariate meta-analyses (accounting for correlated sensitivity and specificity) were used.

As expected given study overlap, FFR-CT performance characteristics were similar to those reported by Danad et al, but with a slightly higher specificity (see Table 1). The pooled per-vessel C statistic was lower (0.86) than the per-patient result (0.90). No evidence of publication bias was detected, but the number of studies was too small to adequately assess. Reviewers noted that, in two studies, FFR-CT results were uninterpretable in 12.0%17 and 8.2%32 of participants.

Takx et al

Takx et al (2015) identified studies reporting on the ability of perfusion computed tomography (CT), MRI, SECHO, PET, and SPECT to detect hemodynamically significant CAD as measured by ICA with invasive FFR. Studies published through May 2014 were eligible for inclusion; PubMed, EMBASE, and Web of Science were searched. QUADAS-2 was used to assess study quality; studies generally rated poorly on blinding of the index test result from the assessor and study population selection. Reviewers designated the negative likelihood ratio as the diagnostic characteristic of interest (i.e., ability to exclude disease) noting that MPI (e.g., MRI, SPECT, PET, or CT) has been proposed to be a gatekeeper to ICA. No funding was obtained for the review and the study was registered on PROSPERO (the two other meta-analyses were not).

The pooled negative likelihood ratios for MRI, PET, and perfusion CT were similar in magnitude (0.12 to 0.14; see Table 1) although the confidence interval for PET was wide. Heterogeneity among studies included in the pooled patient-level results was considered high for PET (I2=84%), moderate for CT (I2=70%) and SPECT (I2=55%), and low for MRI (I2=0%) and SECHO (I2=0%). Publication bias, when able to be assessed, was not suspected. With respect to ability to detect hemodynamically significant ischemia, reviewers concluded that “MPI with MRI, CT, or PET has the potential to serve as a gatekeeper for invasive assessment of hemodynamic significance by ICA and FFR.” Studies of FFR-CT were not included in the analysis.

Table 1: Pooled Per-Patient Pooled Diagnostic Performance of Noninvasive Tests for Invasive Fractional Flow Reserve

Test

Studies

N

Sensitivity

(95% CI)

Specificity

(95% CI)

C

LR+ (95% CI)

LR- (95% CI)

Danad et al (2016)

 

 

 

 

 

 

MRI

2

70

90% (75 to 97)

94% (79 to 99)

0.94

10.3 (3.14 to 33.9)

0.12 (0.05 to 0.30)

FFR-CT

3

609

90% (85 to 93)

71% (65 to 75)

0.94

3.3 (1.78 to 6.25)

0.16 (0.11 to 0.23)

CTA

4

694

90% (86 to 93)

39% (34 to 44)

0.57

1.5 (1.25 to 1.90)

0.22 (0.10 to 0.50)

SECHO

2

115

77% (61 to 88)

75% (63 to 85)

0.82

3.0 (1.94 to 4.65)

0.34 (0.17 to 0.66)

SPECT

3

110

70% (59 to 80)

78% (68 to 87)

0.79

3.4 (1.04 to 11.1)

0.40 (0.19 to 0.83)

ICA

2

954

69% (65 to 75)

67% (63 to 71)

0.75

2.5 (1.25 to 5.13)

0.46 (0.39 to 0.55)

Wu et al (2016)

 

 

 

 

 

 

FFR-CT

5

683

89% (85 to 93)

76% (64 to 84)

0.90

3.7 (2.41 to 5.61)

0.14 (0.09 to 0.21)

Takx et al (2015)

MRI

10

798

89% (86 to 92)

 87% (83 to 90)

0.94

 6.3 (4.88 to 8.12)

 0.14 (0.10 to 0.18)

PCT

5

316

88% (82 to 92)

 80% (73 to 86)

0.93

 3.8 (1.94 to 7.40)

 0.12 (0.04 to 0.33)

SECHO

4

177

69% (56 to 79)

 84% (75 to 90)

0.83

 3.7 (1.89 to 7.15)

 0.42 (0.30 to 0.59)

SPECT

8

533

74% (67 to 79)

 79% (74 to 83)

0.82

 3.1 (2.09 to 4.70)

 0.39 (0.27 to 0.55)

PET

2

224

84% (75 to 91)

 87% (80 to 92)

0.93

 6.5 (2.83 to 15.1)

 0.14 (0.02 to 0.87)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CCTA: coronary computed tomography angiography; CI: confidence interval; CTA: computed tomography angiography; FFR-CT: fractional flow reserve using computed tomography angiography; ICA: invasive coronary angiography; LR: likelihood ratio; MRI: magnetic resonance imaging; SECHO: stress echocardiography; SPECT: single-photon emission computed tomography.

Section Summary: Clinically Valid

The number of studies (n=3) and patients (n=609) evaluated using FDA-cleared HeartFlow software. Software used in successive studies was also revised to improve performance characteristics, particularly specificity. For example, using an earlier software version in the DeFACTO Trial reported a specificity of 54%. Accordingly, pooled results from Danad et al systematic review must be interpreted carefully. In addition, there is some uncertainty in the generalizability of results obtained in these studies conducted under likely controlled conditions (e.g., data from the NXT Trial forming the basis for FDA clearance).

Given the purpose to avoid ICA, the negative likelihood ratio, or how a negative result might dissuade a clinician from proceeding to ICA, is of interest – i.e., excluding a patient with vessels having a high FFR from ICA. While confidence intervals are relatively wide and overlapping, the negative likelihood ratio estimates of FFR-CT for excluding physiologically significant coronary stenoses tended to be lower (i.e. better) than CCTA alone, SECHO, SPECT, and ICA. Only MRI yielded a similarly low or lower negative likelihood ratio than FFR-CT.

Clinically Useful

A test is clinically useful if the use of the results informs management decisions that improve the net health outcome of care. The net health outcome can be improved if patients receive correct therapy, or more effective therapy, or avoid unnecessary therapy, or avoid unnecessary testing.

Direct Evidence

Direct evidence of clinical utility is provided by studies that have compared health outcomes for patients managed with and without the test. Because these are intervention studies, the preferred evidence would be from randomized controlled trials.

We identified two prospective comparative studies including one prospective nonrandomized study that compared an FFR-CT strategy (CCTA with noninvasive FFR measurement when requested or indicated) with ICA and one randomized controlled trial that examined CCTA as a gatekeeper to ICA (see Tables 4 and 5). In addition, we identified one prospective cohort study and two retrospective cohort studies of patients referred for CCTA, which included FFR-CT evaluation.

PLATFORM Study

The PLATFORM (Prospective LongitudinAl Trial of FFRCT: Outcome and Resource Impacts) study compared diagnostic strategies with or without FFR-CT in patients with suspected stable angina but without known CAD. The study was conducted at 11 EU sites. All testing was nonemergent. Patients were divided into two strata according whether the test planned prior to study enrollment was: (1) noninvasive or (2) ICA (the patient population of interest in this evidence review). Patients were enrolled in consecutive cohorts with the first cohort undergoing a usual care strategy followed by a second cohort provided CCTA with FFR-CT performed when requested (recommended if stenoses ≥30% were identified). Follow-up was scheduled at 90 days and 6 and 12 months after entry (99.5% of patients had one-year follow-up data). Funding was provided by HeartFlow and multiple authors reported receiving fees, grants, and/or support from HeartFlow. Data analyses were performed by the Duke Clinical Research Institute.

ICA without obstructive disease at 90 days was the primary end point in patients with planned invasive testing —“no stenosis ≥ 50% by core laboratory quantitative analysis or invasive FFR < 0.80.” Secondary end points included ICA without obstructive disease following planned noninvasive testing, and (1) major adverse cardiovascular events (MACE) at one year defined as a composite of all-cause mortality, myocardial infarction, and urgent revascularization and (2) MACE and vascular events within 14 days. Quality of life (QOL) was evaluated using the Seattle Angina Questionnaire, and EQ-5D (5-item and 100-point visual analog scale). CCTA studies were interpreted by site investigators; quantitative coronary angiography measurements were performed at a central laboratory as was FFR-CT. Cumulative radiation was also assessed. A sample size of 380 patients in the invasive strata yielded 90% power to detect a 50% decrease in the primary end point given a 30% event rate (ICA without obstructive disease) with a usual care strategy and a dropout rate up to 10%.

ICA was planned in 380 participants, of whom 193 (50.8%) had undergone prior noninvasive testing. The mean pretest probability in the planned ICA strata was approximately 50% (51.7 and 49.4% in the two groups). FFR-CT was requested in 134 patients and successfully obtained 117 (87.3%) in the FFR-CT group. At 90 days 73.3% of those in the usual care group had no obstructive findings on ICA compared with 12.4% in the FFR-CT group based on core laboratory readings (56.7% and 9.3% based on site readings). The difference was similar in a propensity-matched analysis of a subset of participants (n=148 from each group or 78% of the entire sample). Prior noninvasive testing did not appear associated with the rate of nonobstructive findings. MACE rates were low and did not differ between strategies. Mean level of radiation exposure though one year was also similar in both groups (10.4 and 10.7 mSv with usual care and FFR-CT, respectively). No differences in QOL were found between groups.

Results of the PLATFORM study support the notion that, in patients with planned ICA, FFR-CT can decrease the rate of ICAs and unnecessary procedures (finding no significant obstructive disease) and that FFR-CT may provide clinically useful information to physicians and patients. Study limitations include a nonrandomized design, high rate of no obstructive disease with a usual care strategy (73.3%), which was higher than the 30% rate assumed in the sample size estimates; and a sample size that was small with respect to evaluating adverse cardiac events. Although finding a large effect in patients with planned invasive testing, the nonrandomized design limits causal inferences and certainty in the magnitude of effect. The propensity-matched analysis (in a matched subset) offers some reassurance, but the sample size was likely too small to provide robust results.

CAD-Man Trial

Dewey et al (2016) conducted the Coronary Artery Disease Management (CAD-Man) trial, a single-center, parallel-group assignment trial examining CCTA as a gatekeeper to ICA in patients with atypical angina or chest pain and suspected CAD who were indicated for ICA. Patients were randomized to direct ICA or to ICA only if a prior CCTA was positive (a stenosis ≥70% stenosis in any vessel or ≥50% in the left main coronary artery). The trialists reported that when obstructive disease was suspect following CCTA, late enhancement MRI was performed to evaluate the extent of viable myocardium (completed in 17 patients) to guide revascularization; however, the study protocol clarified that MRI was not used for decisions to proceed to ICA. A major procedural complication (death, stroke, MI, or event requiring >24-hour hospitalization) within 24 hours was the primary outcome; secondary outcomes included ICA with obstructive CAD (diagnostic yield), revascularizations, and MACE during long-term follow-up. The trial was performed in Germany. Patients were excluded if they had evidence of ischemia or signs of MI and just over half (56.5%) were inpatients at the time of enrollment. Obstructive disease was defined as “at least one 50% diameter stenosis in the left main coronary artery or at least one 70% diameter stenosis in other coronary arteries.” Allocation concealment appeared adequate, but the trial was unblinded owing to the nature of the intervention. In addition, the mean pretest probability of CAD at baseline was higher in the ICA-only arm (37.3% vs. 31.3%; see Table 2). The research was supported by public funding.

ICAs were reduced by 85.6% in the CCTA arm and by 80.9% for ICA with no obstructive disease. A major procedural complication (the primary outcome) occurred in a single patient undergoing CCTA. PCIs were less frequent when CCTA was performed—9.6% versus 14.2% (p<0.001). Over a median follow-up of 3.3 years, MACE rates were similar in the trial arms (4.2% in the CCTA group vs 3.7% with ICA; adjusted hazard ratio [HR], 0.90; 95% CI, 0.30 to 2.69). In the CCTA arm, there was 1 death, 2 patients with unstable angina, and 6 revascularizations; in the ICA arm there was 1 MI, 1 stroke, and 5 revascularizations.

The trial demonstrated that CCTA as a gatekeeper to planned ICA can avoid a large number of procedures, a corresponding increase in the diagnostic yield, and fewer revascularizations. Of note, the prevalence of obstructive CAD found on ICA in this study population was 13% (43/334 eligible for primary outcome analysis), which is lower than the prevalence of obstructive CAD in the PLATFORM population (26.7%). Thus, the subset of individuals who went onto ICA following CCTA findings of obstructive CAD was 20 (12%) of 167 eligible for primary outcome analysis and only three (1.7%) were found to have no obstructive CAD on ICA. MACE rates did not differ between arms. The trial was powered neither to detect a difference nor to assess noninferiority—implications of the absence of a difference are limited. Finally, although the patient population included those scheduled for elective ICA, it was heterogeneous, including those with recent onset and longer standing chest pain. The single-center nature of the trial is an additional limitation; a subsequent multicenter trial (DISCHARGE) is ongoing.

Table 2. Characteristics of Comparative Studies

Characteristics

Nonrandomized

Randomized

PLATFORM

CAD-Man

ICA

FFR-CT

ICA

CCTA

(n=187)

(n=193)

(n=162)

(n=167)

Age (SD), y

63.4 (10.9)

60.7 (10.2)

60.4 (11.4)

60.4 (11.3)

Female, n (%)

79 (42.2%)

74 (38.3%)

88 (52.7%)

78 (48.1%)

Race/ethnic minority, n (%)

2 (1.1%)

1 (0.5%)

Pretest probability obstructive CAD, % (SD)

51.7% (16.7%)

49.4% (17.2%)

37.3% (24.8%)

31.3% (21.1%)

Angina (%)

Typical

52 (27.8%)

45 (23.3%)

Atypical

122 (65.2%)

142 (73.6%)

79 (48.8%)

65 (38.9%)

Noncardiac

12 (7.0%)

5 (2.6%)

80 (49.4%)

97 (58.1%)

Other chest discomfort

3 (1.8%)

5 (3.0%)

Prior noninvasive testing, n (%)

92 (49.2%)

101 (52.3%)

84 (50.3%)

92 (56.8%)

Diabetes, n (%)

36 (19.3%)

30 (15.5%)

30 (18.5%)

15 (9.0%)

Current smoker

34 (21.0%)

41 (24.5%)

Current or past smoker

103 (55.1%)

101 (52.3%)

85 (52.4%)

88 (52.6%)

CAD: coronary artery disease; CCTA: coronary computed tomography angiography; FFR-CT: fractional flow
reserve using coronary computed tomography angiography; ICA: invasive coronary angiography

Table 3. Results of Comparative Studies

Outcomes

Nonrandomized

Randomized

PLATFORM

CAD-Man

ICA

FFR-CT

ICA

CCTA

(n=187)

(n=193)

(n=162)

(n=167)

Noninvasive FFR-CT

Requested, n (%)

134 (69.4%)

Successfully performed, n (%)

117 (60.1%)

ICA no obstructive disease, n (%)

137 (73.3%)

24 (12.4%)

137 (84.5%)

6 (3.6%)

Absolute difference (95% CI), %

60.8% (53.0% to 68.7%)

80.9% (74.6% to 87.2%)

ICA, n (%)

187 (100%)

76 (39.4%)

162 (100%)

24 (14.4%)

Absolute difference (95% CI), %

60.6% (53.7% to 67.5%)

85.6% (80.3% to 90.9%)

Revascularization, n (%)

PCI

49 (26.2%)

55 (28.5%)

CABG

18 (9.6%)

10 (5.2%)

Any

67 (35.8%)

65 (33.7%)

23 (14.2%)

16 (9.6%)

1-year outcomes, n (%)

MACEa

2 (1.1%)

2 (1.0%)

MACEb

6 (3.7%)

7 (4.2%)

CABG: coronary artery bypass grafting; CI: confidence interval; FFR-CT: fractional flow reserve using coronary computed tomography angiography; ICA: invasive coronary angiography; MACE: major adverse cardiovascular events; PCI: percutaneous coronary intervention.
a Death, myocardial infarction, unplanned urgent revascularization
b Cardiac death, myocardial infarction, stroke, unstable angina, any revascularization.

Jensen et al Prospective Cohort

Jensen et al (2018) reported on a single-institution study of 774 consecutive individuals with suspicion of CAD referred for nonemergent ICA or CCTA. Subjects were analyzed in two groups: a low-intermediate-risk group accounting for 76% of patients with mean pretest probability of CAD 31% and a high-risk group accounting for 24% of patients with mean pretest probability of CAD 67%. Among the 745 who received CCTA, FFR-CT was selectively ordered in 28% of patients overall (23% in the low-intermediate-risk group, 41% in the high-risk group). CCTA was considered inconclusive in 3% of subjects and among those with conclusive CCTA, FFR-CT yielded few inconclusive results, with less than 3% of cases. During a minimum 90-day follow-up, the combined testing strategy of selective FFR-CT following CCTA resulted in avoiding ICA in 91% of low-intermediate-risk and 75% of high-risk individuals. None of the patients who avoided ICA based on CCTA with selective FFR-CT were associated with serious clinical adverse events over an average of 157 days of follow-up.

Nørgaard et al Retrospective Cohort

Nørgaard et al (2017) reported results from symptomatic patients referred for coronary CTA at a single center in Denmark from May 2014 to April 2015. All data were obtained from medical records and registries; the study was described as a “review” of diagnostic evaluations and apparently retrospectively conducted. Follow-up through 6 to 18 months was ascertained. From 1,248 referred patients, 1,173 underwent coronary CTA; 858 received medical therapy, 82 underwent ICA, 44 perfusion imaging, and 189 FFR-CT (185 [98%] obtained successfully). Of the 185 individuals who successfully obtained FFR-CT, FFR-CT demonstrated values of 0.80 or less in one or more vessels in 57 (31%) patients and 49 (86%) went on to ICA; whereas of the 128 with higher FFR-CT values, only five (4%) went on to ICA. Assuming ICA was planned for all patients undergoing FFR-CT, these results are consistent with FFR-CT being able to decrease the rate of ICA. However, implications are limited by the retrospective design, performance at a single center, and lack of a comparator arm including one for CCTA alone.

Lu et al Retrospective Cohort

Lu et al (2017) retrospectively examined a subgroup referred to ICA from the completed PROspective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) trial. PROMISE was a pragmatic trial comparing CCTA with functional testing for the initial evaluation of patients with suspected SIHD. Of 550 participants referred to ICA within 90 days, 279 were not considered for the analyses due to CCTA performed without nitroglycerin (n=139), CCTA not meeting slice thickness guidelines (n=90), or nondiagnostic studies (n=50). Of the remaining 271 patients, 90 scans were inadequate to obtain FFR-CT, leaving 181 (33%) of those referred to ICA for analysis. Compared with those excluded, patients in the analytic sample were less often obese, hypertensive, diabetic, minority, or reported a CAD equivalent symptom. The 2 groups had similar pretest probabilities of disease, revascularization rates, and MACE, but the distribution of stenoses in the analytic sample tended to be milder (p=0.06). FFR-CT studies were performed in a blinded manner and not available during the conduct of PROMISE for decision making.

Severe stenoses (≥70%) or left main disease (≥50%) were present in 110 (66%) patients by CCTA result and in 54% by ICA. Over a 29-month median follow-up, MACE (death, nonfatal MI, hospitalization for unstable angina) or revascularization occurred in 51% of patients (9% MACE, 49% revascularization). A majority (72%) of the sample had at least one vessel with an FFR-CT ≤0.80, which was also associated with a higher risk of revascularization but with a wide confidence interval (HR = 5.1; 95% CI, 2.6 to 11.5). If reserved for patients with an FFR-CT of 0.80 or less, ICAs might have been avoided in 50 patients (i.e., reduced by 28%) and the rate of ICA without 50% or more stenosis from 27% (calculated 95% CI, 21% to 34%) to 15% (calculated 95% CI, 10% to 23%). If the 90 patients whose images sent for FFR-CT but were unsatisfactory proceeded to ICA—as would have occurred in practice—the rate of ICA might have decreased by 18% and ICA without significant stenosis from 31% to 25%.

The authors suggested that when CCTA is used as the initial evaluation for patients with suspected SIHD, adding FFR-CT could have decreased the referral rate to ICA in PROMISE from 12.2% to 9.5%, or close to the 8.1% rate observed in the PROMISE functional testing arm. They also noted similarity of their findings to PLATFORM and concluded, “In this hypothesis-generating study of patients with stable chest pain referred to ICA after [C]CTA, we found that adding FFRCT may improve the efficiency of referral to ICA, addressing a major concern of an anatomic [C]CTA strategy. FFRCT has incremental value over anatomic [C]CTA in predicting revascularization or major adverse cardiovascular events.”

This retrospective observational subgroup analysis from PROMISE suggests that when CCTA is the initial noninvasive test for the evaluation of suspected SIHD, FFR-CT prior to ICA has the potential to reduce unnecessary ICAs and increase the diagnostic yield. However, study limitations and potential generalizability are important to consider. First, analyses included only a third of CCTA patients referred to ICA and the some characteristics of the excluded group differed from the analytic sample. Second, conclusions assume that an FFR-CT greater than 0.80 will always dissuade a physician from recommending ICA and even in the presence of severe stenosis (e.g., ≥70% in any vessel or ≥50% in the left main)—or almost half (46%) of patients with an FFR-CT greater than 0.80. Finally, estimates including patients with either nondiagnostic CCTA studies (n=50) or studies inadequate for calculating FFR-CT (n=90) are more appropriate because most likely those patients would proceed in practice to ICA. Accordingly, the estimates are appropriately considered upper bounds for what might be seen in practice. It is also important to note that in strata of the PLATFORM trial enrolling patients for initial noninvasive testing (not planned ICA), ICA was more common following CCTA and contingent FFR-CT than following usual care (18.3% vs. 12.0%) and ICA, with no obstructive disease more frequent in the FFR-CT arm (12.5% vs. 6.0%).

Chain of Evidence

Indirect evidence on clinical utility rests on clinical validity. If the evidence is insufficient to demonstrate test performance, no inferences can be made about clinical utility.

Diagnostic performance can offer indirect evidence of clinical utility, assuming providers act according to a test result. As previously noted, an effective gatekeeper strategy must be able to decrease the probability of disease (rule out) sufficiently that a planned ICA would not be performed. Ruling out disease is a function of the negative likelihood ratio that defines the degree to which a negative test decreases the posttest odds (and probability) of disease.

Table 4 illustrates how a negative test would lower the probability of a hemodynamically significant obstruction from pretest probabilities of 0.25, 0.50, or 0.75 for the various tests examined in the meta-analyses. For example, according to the results of Danad et al, if the pretest probability was 0.50, following a negative CCTA study the posttest probability would be 0.18 (95% CI, 0.09 to 0.33); and following a negative SECHO, 0.25 (95% CI, 0.15 to 0.40) or SPECT, 0.29 (95% CI, 0.16 to 0.45). In contrast, beginning with a pretest probability of 0.50, a negative FFR-CT would yield a posttest probability of 0.14 (95% CI, 0.10 to 0.19) (Danad et al) and 0.12 (95% CI, 0.08 to 0.17) (Wu et al). Overall, the negative likelihood ratios and posttest probability estimates for FFR-CT are slightly better than CCTA as well as SECHO and SPECT.

Table 4. Change in Disease Probability Following a Negative Test

Posttest Probability (95% CI) After Negative Test

Study

Modality

Negative LR
(95% CI)

Pretest Probability 0.25

Pretest Probability

0.50

Pretest Probability

0.75

Danad et al (2016)

MRI

0.12 (0.05 to 0.30)

0.04 (0.02 to 0.09)

0.11 (0.05 to 0.23)

0.26 (0.13 to 0.47)

FFR-CT

0.16 (0.11 to 0.23)

0.05 (0.04 to 0.07)

0.14 (0.10 to 0.19)

0.32 (0.25 to 0.41)

CCTA

0.22 (0.10 to 0.50)

0.07 (0.03 to 0.14)

0.18 (0.09 to 0.33)

0.40 (0.23 to 0.60)

SECHO

0.34 (0.17 to 0.66)

0.10 (0.05 to 0.18)

0.25 (0.15 to 0.40)

0.50 (0.34 to 0.66)

SPECT

0.40 (0.19 to 0.83)

0.12 (0.06 to 0.22)

0.29 (0.16 to 0.45)

0.55 (0.36 to 0.71)

ICA

0.46 (0.39 to 0.55)

0.13 (0.12 to 0.15)

0.32 (0.28 to 0.35)

0.58 (0.54 to 0.62)

Wu et al (2016)

FFR-CT

0.14 (0.09 to 0.21)

0.04 (0.03 to 0.07)

0.12 (0.08 to 0.17)

0.30 (0.21 to 0.39)

Takx et al (2015)

MRI

0.14 (0.10 to 0.18)

0.04 (0.03 to 0.06)

0.12 (0.09 to 0.15)

0.30 (0.23 to 0.35)

Perfusion CT

0.12 (0.04 to 0.33)

0.04 (0.01 to 0.10)

0.11 (0.04 to 0.25)

0.26 (0.11 to 0.50)

SECHO

0.42 (0.30 to 0.59)

0.12 (0.09 to 0.16)

0.30 (0.23 to 0.37)

0.56 (0.47 to 0.64)

SPECT

0.39 (0.27 to 0.55)

0.12 (0.08 to 0.15)

0.28 (0.21 to 0.35)

0.54 (0.45 to 0.62)

PET

0.14 (0.02 to 0.87)

0.04 (0.01 to 0.22)

0.12 (0.02 to 0.47)

0.30 (0.06 to 0.72)

CCTA: coronary computed tomography angiography; CI: confidence interval; CT: computed tomography; FFR-CT: fractional flow reserve using coronary computed tomography angiography; ICA: invasive coronary angiography; LR: likelihood ratio; MRI: magnetic resonance imaging; PET: positron emission tomography; SECHO: stress echocardiography; SPECT: single-photon emission computed tomography.

A literature search identified one study (Curzen et al, 2016) that examined 200 consecutive individuals selected from the NXT trial population “to reproduce the methodology of the invasive RIPCORD study” with elective management of stable chest pain. All subjects received CCTA including FFR-CT “in at least one vessel with diameter ≥ 2 mm and diameter stenosis ≥ 30%” as well as ICA within 60 days of CCTA. Three experienced interventional cardiologists reviewed the CCTA results (initially without the FFR-CT results) and selected a management plan from the following four options: “1) optimal medical therapy (OMT) alone; 2) PCI + OMT; 3) coronary artery bypass graft + OMT; or 4) more information about ischemia required – they committed to option one by consensus.” Following the initial decision, results from the FFR-CT were shared with the same group of interventional cardiologists who again made a decision by consensus based on the same four options. A cutoff of 0.80 or less was considered significant on FFR-CT. A stenosis was considered significant on CCTA or ICA with 50% or more diameter narrowing. Change in management between the first decision based on CCTA only and the second decision based on CCTA plus FFR-CT was the primary end point of this study. Secondary end points included analysis of the vessels considered to have significant stenosis based on CCTA alone versus CCTA plus FFR-CT as well as vessels identified as targets for revascularization based on CCTA alone versus CCTA plus FFR-CT. This study was conducted by investigators in the United Kingdom and Denmark. Funding was provided by HeartFlow and multiple authors reported receiving fees, grants, and/or support from HeartFlow.

Results for the primary end point (see Table 5) yielded a change in management category for 72 of 200 (36%) individuals. For the 87 individuals initially assigned to PCI based on CCTA alone, the addition of the FFR-CT results shifted management for 26 of 87 (30%) to OMT (i.e., no ischemic lesion on FFR-CT) and an additional 16 (18%) individuals remained in the PCI category but FFR-CT identified a different target vessel for PCI. These findings provide supportive information that the improved diagnostic accuracy of FFR-CT in particular related to its better negative likelihood ratio compared to CCTA alone would likely lead to changes in management that would be expected to improve health outcomes.

Table 5. Summary of Overall Changes to Management in Patients Using CCTA vs CCTA + FFR-CT

Management Category Consensus Decision

CCTA Alone,

n (%)

CCTA + FFR-CT,

n (%)

Strategy Changea (95% CI)

More data required

38 (19.0%)

0

-

Optimal medical therapy

67 (33.5%)

113 (56.5%)

23% (18% to 29%)

Percutaneous coronary intervention

87 (43.5%)

78 (39.0%)

-5% (-2% to -8%)

Coronary artery bypass graft surgery

8 (4.0%)

9 (4.5%)

0.5% (0.1% to 3%)

CCTA: coronary computed tomography angiography; CI: confidence interval; FFR-CT: fractional flow reserve using coronary computed tomography angiography.
a p<0.001 for between-group change, CCTA alone vs CCTA + FFR-CT

Section Summary: Clinically Useful

There is direct evidence, provided by 2 prospective and 2 retrospective studies, that compares health outcomes observed during 90-day to 1-year follow-up for strategies using CCTA particularly in combination with selective FFR-CT with strategies using ICA or other noninvasive imaging tests. The available evidence provides support that use of CCTA with selective FFR-CT is likely to reduce the use of ICA in individuals with stable chest pain who are unlikely to benefit from revascularization by demonstrating the absence of functionally significant obstructive CAD. Also, the benefits are likely to outweigh potential harms given that rates of revascularization for functionally significant obstructive CAD appear to be similar and cardiac-related adverse events do not appear to be increased following a CCTA with selective FFR-CT strategy. Moreover, the evidence on the diagnostic performance characteristics, particularly showing higher specificity of FFR-CT and better negative likelihood ratio as compared with CCTA alone, may be combined with indirect evidence that CCTA with a selective FFR-CT strategy would likely lead to changes in management that would be expected to improve health outcomes, particularly by limiting unnecessary ICA testing. While individual studies are noted to have specific methodologic limitations and some variation is noted in the magnitude of benefit across studies, in aggregate the evidence provides reasonable support that the selective addition of FFR-CT following CCTA results in a meaningful improvement in the net health outcome.

Summary of Evidence

For individuals with stable chest pain and at intermediate risk of coronary artery disease (CAD; i.e. suspected or presumed stable ischemic heart disease) being considered for invasive coronary angiography (ICA) who receive noninvasive fractional flow reserve measurement following positive coronary computed tomography angiography, the evidence includes both direct and indirect evidence; two meta-analyses of diagnostic performance, one prospective, multicenter nonrandomized comparative study; one prospective cohort; two retrospective cohort studies; and a study reporting changes in management associated with CCTA-based strategies with selective addition of FFR using CCTA and a randomized controlled trial of CCTA alone compared with ICA. Relevant outcomes are test accuracy and validity, morbid events, quality of life, resource utilization, and treatment-related mortality and morbidity. The meta-analyses indicated that CCTA has high sensitivity but moderately low specificity for hemodynamically significant obstructive disease. There is direct evidence, provided by two prospective and two retrospective studies, that compares health outcomes observed during 90-day to one-year follow-up for strategies using CCTA particularly in combination with selective FFR-CT with strategies using ICA or other noninvasive imaging tests. The available evidence provides support that use of CCTA with selective FFR-CT is likely to reduce the use of ICA in individuals with stable chest pain who are unlikely to benefit from revascularization by demonstrating the absence of functionally significant obstructive CAD. In addition, the benefits are likely to outweigh potential harms because rates of revascularization for functionally significant obstructive CAD appear to be similar and treatment-related adverse events do not appear to increase following CCTA with a selective FFR-CT strategy. Moreover, given the available evidence that CCTA alone has been used to select patients to avoid ICA, the studies showing higher specificity of FFR-CT and lower negative likelihood ratio of FFR-CT compared with CCTA alone, may be used to build a chain of evidence that CCTA with a selective FFR-CT strategy would likely lead to changes in management that would be expected to improve health outcomes by further limiting unnecessary ICA testing. While individual studies are noted to have specific methodologic limitations and some variation has been noted in the magnitude of benefit across studies, in aggregate the evidence provides reasonable support that the selective addition of FFR-CT following CCTA results in a meaningful improvement in the net health outcome. The evidence is sufficient to determine that the technology results in meaningful improvements in the net health outcome

Practice Guidelines and Position Statements

National Institute for Health and Care Excellence

In 2017, the National Institute for Health and Care Excellence endorsed fractional flow reserve using coronary computed tomography angiography (FFR-CT), with the following conclusions: “The committee concluded that the evidence suggests that HeartFlow FFRCT is safe, has high diagnostic accuracy, and that its use may avoid the need for invasive investigations.”

Recommendations included:

  • “The case for adopting HeartFlow FFR-CT for estimating fractional flow reserve from coronary CT angiography (CCTA) is supported by the evidence. The technology is non-invasive and safe, and has a high level of diagnostic accuracy.”

  • “HeartFlow FFR-CT should be considered as an option for patients with stable, recent onset chest pain who are offered CCTA as part of the NICE pathway on chest pain. Using HeartFlow FFR-CT may avoid the need for invasive coronary angiography and revascularization. For correct use, HeartFlow FFR-CT requires access to 64-slice (or above) CCTA facilities.”

U.S. Preventive Services Task Force Recommendations

Not applicable.

KEY WORDS:

FFR, FFR-CT, FFRCT, fractional flow reserve, HeartFlow

APPROVED BY GOVERNING BODIES:

In November 2014, FFRCT simulation software (HeartFlow) was cleared for marketing by the U.S. Food and Drug Administration (FDA) through the de novo 510(k) process (Class II, special controls). In January 2016, the FFRCT v2.0 device was cleared through a subsequent 510(k) process.

HeartFlow FFRCT postprocessing software is cleared “for the clinical quantitative and qualitative analysis of previously acquired Computed Tomography (CT) DICOM [Digital Imaging and Communications in Medicine] data for clinically stable symptomatic patients with coronary artery disease. It provides FFRCT, a mathematically derived quantity, computed from simulated pressure, velocity and blood flow information obtained from a 3D computer model generated from static coronary CT images. FFRCT analysis is intended to support the functional evaluation of coronary artery disease.” “The results of this analysis [FFRCT] are provided to support qualified clinicians to aid in the evaluation and assessment of coronary arteries. The results of HeartFlow FFRCT are intended to be used by qualified clinicians in conjunction with the patient’s clinical history, symptoms, and other diagnostic tests, as well as the clinician’s professional judgment.”

BENEFIT APPLICATION:

Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply.

FEP:  Special benefit consideration may apply.  Refer to member’s benefit plan.  FEP does not consider investigational if FDA approved and will be reviewed for medical necessity.

CURRENT CODING: 

0501T

 Noninvasive estimated coronary fractional flow reserve (FFR) derived from coronary computed tomography angiography data using computation fluid dynamics physiologic simulation software analysis of   functional data to assess the severity of coronary artery disease; data preparation and transmission, analysis of fluid dynamics and simulated maximal coronary hyperemia, generation of estimated FFR   model, with anatomical data review in comparison with estimated FFR model to reconcile discordant data, interpretation and report (Effective 01/01/2018)

0502T

 ; data preparation and transmission (Effective 01/01/2018)

0503T

 ; analysis of fluid dynamics and simulated maximal coronary hyperemia, and generation of estimated FFR model (Effective 01/01/2018)

0504T

 ; anatomical data review in comparison with estimated FFR model to reconcile discordant data, interpretation and report (Effective 01/01/2018)

 

Prior to January 1, 2018, there is was specific CPT code for fractional flow reserve using coronary computed tomographic angiography. The applicable unlisted code until that time would be:

93799

 Unlisted cardiovascular service or procedure 

                             

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  35. Montalescot G, Sechtem U, Achenbach S, et al. 2013 ESC guidelines on the management of stable coronary artery disease: the Task Force on the management of stable coronary artery disease of the European Society of Cardiology. Eur Heart J. Oct 2013; 34(38):2949-3003.

  36. National Institute for Health and Care Excellence. HeartFlow FFRCT for estimating fractional flow reserve from coronary CT angiography [MTG32]. 2017; www.nice.org.uk/guidance/mtg32. Accessed April 20, 2018.

  37. Nakazato R, Park HB, Berman DS, et al. Noninvasive fractional flow reserve derived from computed tomography angiography for coronary lesions of intermediate stenosis severity: results from the DeFACTO study. Circ Cardiovasc Imaging. Nov 2013; 6(6):881-889.

  38. Nørgaard BL, Gaur S, Leipsic J, et al. Influence of coronary calcification on the diagnostic performance of CT angiography derived FFR in coronary artery disease: a substudy of the NXT Trial. JACC Cardiovasc Imaging. Sep 2015; 8(9):1045-1055.

  39. Nørgaard BL, Hjort J, Gaur S, et al. Clinical Use of Coronary CTA-Derived FFR for Decision-Making in Stable CAD. JACC Cardiovasc Imaging. Apr 7 2016.

  40. Nørgaard BL, Leipsic J, Gaur S, et al. Diagnostic performance of noninvasive fractional flow reserve derived from coronary computed tomography angiography in suspected coronary artery disease: the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps). J Am Coll Cardiol. Apr 1 2014; 63(12):1145-1155.

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POLICY HISTORY:

Medical Policy Panel, December 2016

Medical Policy Group, January 2017 (3): Newly Adopted Policy

Available for comment January 6 through February 21, 2017

Medical Policy Panel, June 2017

Medical Policy Group, August 2017 (3): 2017 Updates to Description, Key Points, Coding, and References.  Policy statement updated to state that noninvasive FFR meets for coverage when used to guide decisions about the use of invasive coronary angiography in patients with stable chest pain at intermediate risk of coronary artery disease (i.e. suspected or presumed stable ischemic heart disease)

Medical Policy Administrative Committee: August 2017

Available for comment August 14 through September 27, 2017

Medical Policy Group, December 2017: Annual Coding Update 2017: Added new CPT codes 0501T, 0502T, 0503T, 0504T, and 93799 to Current Coding.

Medical Policy Panel, May 2018

Medical Policy Group, May 2018 (4): Updates to Description, Key Points, and References.  No change in policy statement.


This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.