Prognosis of CT-derived Fractional Flow Reserve in the Prediction of Clinical Outcomes

Utility of Fractional Flow Reserve Computed Tomography Angiography in Patients With Stable Coronary Artery Disease

Coronary computed tomography angiography is a modality with high negative predictive value for evaluation of coronary artery disease (CAD). However, its diagnostic accuracy for obstructive CAD is limited by multiple factors. Fractional flow reserve (FFR) computed tomography (FFRCT) is an emerging analysis tool for identifying flow-limiting disease; nonetheless, the prognostic value of FFRCT is not well established. This meta-analysis aims to evaluate the association of FFRCT with clinical outcomes in patients with stable CAD. A literature search was conducted for studies reporting the association between FFRCT measurements and all-cause mortality, major adverse cardiovascular events (MACEs), acute myocardial infarction (AMI), and any need for coronary revascularization. Obstructive disease was defined as a FFR value ≤0.80; nonobstructive disease was defined as an FFR value >0.80. Ten studies were identified to meet the inclusion criteria; mean follow-up was 17 months (range, 3 to 56 months). There was no difference in risk of all-cause mortality between patients with obstructive and those with nonobstructive CAD on FFRCT. However, obstructive lesions were associated with increased risk of MACE, AMI, and any need for revascularization. FFRCT is a useful adjunctive modality for further risk stratification of patients with stable CAD. Obstructive lesions identified by FFRCT are associated with increased risk of MACE, AMI, and any need for revascularization.

Prognostic Value of Coronary CT Angiography-derived Fractional Flow Reserve on 3-year Outcomes in Patients with Stable Angina

Background The prognostic value of coronary CT angiography (CTA)-derived fractional flow reserve (FFR) beyond 1-year outcomes and in patients with high levels of coronary artery calcium (CAC) is uncertain. Purpose To assess the prognostic value of coronary CTA-derived FFR test results on 3-year clinical outcomes in patients with coronary stenosis and among a subgroup of patients with high levels of CAC. Materials and Methods This study represents a 3-year follow-up of patients with new-onset stable angina pectoris who were consecutively enrolled in the Assessing Diagnostic Value of Noninvasive CT-FFR in Coronary Care, known as ADVANCE (ClinicalTrials.gov: NCT02499679) registry, between December 2015 and October 2017 at three Danish sites. A high CAC was defined as an Agatston score of at least 400. A lesion-specific coronary CTA-derived FFR value of 2 cm with distal-to-stenosis value at or below 0.80 represented an abnormal test result. The primary end point was a composite of all-cause death and nonfatal spontaneous myocardial infarction. Event rates were estimated using the one-sample binomial model, and relative risk was compared between participants stratified by results of coronary CTA-derived FFR. Results This study included 900 participants: 523 participants with normal results (mean age, 64 years ± 9.6 [SD]; 318 male participants) and 377 with abnormal results from coronary CTA-derived FFR (mean age, 65 years ± 9.6; 264 male participants). The primary end point occurred in 11 of 523 (2.1%) and 25 of 377 (6.6%) participants with normal and abnormal coronary CTA-derived FFR results, respectively (relative risk, 3.1; 95% CI: 1.6, 6.3; P < .001). In participants with high CAC, the primary end point occurred in four of 182 (2.2%) and 19 of 212 (9.0%) participants with normal and abnormal coronary CTA-derived FFR results, respectively (relative risk, 4.1; 95% CI: 1.4, 11.8; P = .001). Conclusion In individuals with stable angina, a normal coronary CTA-derived FFR test result identified participants with a low 3-year risk of all-cause death or nonfatal spontaneous myocardial infarction, both in the overall cohort and in participants with high CAC scores. Clinical trial registration no. NCT02499679 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Sinitsyn in this issue.

Integration of fractional flow reserve derived from CT into clinical practice

Fractional flow reserve (FFR) is currently considered as the gold standard for revascularization decision-making in patients with stable coronary artery disease (CAD). The application of computational fluid dynamics to coronary computed tomography (CT) angiography (CCTA) enables calculation of FFR without additional testing, radiation exposure, contrast medium injection, and hyperemia (FFR_CT). Although multiple diagnostic and clinical studies have enriched the scientific evidence, it is still challenging to integrate FFR_CT into clinical practice. Both meticulous scientific backgrounds and precise anatomical data derived from CCTA are fundamental for FFR_CT computation, and there are numerous factors impacting on FFR_CT calculation and interpretation: coronary artery stenosis, calcium, atherosclerosis, luminal volume, and left ventricular myocardial mass. Further, there is a gap that clinicians using FFR_CT need to recognize in interpretation of FFR_CT results between diagnostic studies and clinical studies. In this review, we summarize multiple evidence related to FFR_CT computation and interpretation to refine the FFR_CT strategy in patients with stable CAD.

Prognostic value of coronary computed tomography angiographic derived fractional flow reserve: a systematic review and meta-analysis

Objectives

To obtain more powerful assessment of the prognostic value of fractional flow reserve_CT testing we performed a systematic literature review and collaborative meta-analysis of studies that assessed clinical outcomes of CT-derived calculation of FFR (FFR_CT) (HeartFlow) analysis in patients with stable coronary artery disease (CAD).

Methods

We searched PubMed and Web of Science electronic databases for published studies that evaluated clinical outcomes following fractional flow reserve_CT testing between 1 January 2010 and 31 December 2020. The primary endpoint was defined as ‘all-cause mortality (ACM) or myocardial infarction (MI)’ at 12-month follow-up. Exploratory analyses were performed using major adverse cardiovascular events (MACEs, ACM+MI+unplanned revascularisation), ACM, MI, spontaneous MI or unplanned (>3 months) revascularisation as the endpoint.

Results

Five studies were identified including a total of 5460 patients eligible for meta-analyses. The primary endpoint occurred in 60 (1.1%) patients, 0.6% (13/2126) with FFR_CT>0.80% and 1.4% (47/3334) with FFR_CT ≤0.80 (relative risk (RR) 2.31 (95% CI 1.29 to 4.13), p=0.005). Likewise, MACE, MI, spontaneous MI or unplanned revascularisation occurred more frequently in patients with FFR_CT ≤0.80 versus patients with FFR_CT >0.80. Each 0.10-unit FFR_CT reduction was associated with a greater risk of the primary endpoint (RR 1.67 (95% CI 1.47 to 1.87), p<0.001).

Conclusions

The 12-month outcomes in patients with stable CAD show low rates of events in those with a negative FFR_CT result, and lower risk of an unfavourable outcome in patients with a negative test result compared with patients with a positive test result. Moreover, the FFR_CT numerical value was inversely associated with outcomes.

Coronary Computed Tomography Angiography From Clinical Uses to Emerging Technologies: JACC State-of-the-Art Review

Evaluation of coronary artery disease (CAD) using coronary computed tomography angiography (CCTA) has seen a paradigm shift in the last decade. Evidence increasingly supports the clinical utility of CCTA across various stages of CAD, from the detection of early subclinical disease to the assessment of acute chest pain. Additionally, CCTA can be used to noninvasively quantify plaque burden and identify high-risk plaque, aiding in diagnosis, prognosis, and treatment. This is especially important in the evaluation of CAD in immune-driven conditions with increased cardiovascular disease prevalence. Emerging applications of CCTA based on hemodynamic indices and plaque characterization may provide personalized risk assessment, affect disease detection, and further guide therapy. This review provides an update on the evidence, clinical applications, and emerging technologies surrounding CCTA as highlighted at the 2019 National Heart, Lung and Blood Institute CCTA Summit.