Fractional flow reserve (FFR) has become an established tool for guiding treatment, but its graded relationship to clinical outcomes as modulated by medical therapy versus revascularization remains unclear. The study hypothesized that FFR displays a continuous relationship between its numeric value and prognosis, such that lower FFR values confer a higher risk and therefore receive larger absolute benefits from revascularization. Meta-analysis of study- and patient-level data investigated prognosis after FFR measurement. An interaction term between FFR and revascularization status allowed for an outcomes-based threshold. A total of 9,173 (study-level) and 6,961 (patient-level) lesions were included with a median follow-up of 16 and 14 months, respectively. Clinical events increased as FFR decreased, and revascularization showed larger net benefit for lower baseline FFR values. Outcomes-derived FFR thresholds generally occurred around the range 0.75 to 0.80, although limited due to confounding by indication. FFR measured immediately after stenting also showed an inverse relationship with prognosis (hazard ratio: 0.86, 95% confidence interval: 0.80 to 0.93; p < 0.001). An FFR-assisted strategy led to revascularization roughly half as often as an anatomy-based strategy, but with 20% fewer adverse events and 10% better angina relief. FFR demonstrates a continuous and independent relationship with subsequent outcomes, modulated by medical therapy versus revascularization. Lesions with lower FFR values receive larger absolute benefits from revascularization. Measurement of FFR immediately after stenting also shows an inverse gradient of risk, likely from residual diffuse disease. An FFR-guided revascularization strategy significantly reduces events and increases freedom from angina with fewer procedures than an anatomy-based strategy.

The present analysis addresses the potential clinical and physiologic significance of discordance in severity of coronary artery disease between the angiogram and fractional flow reserve (FFR) in a large and unselected patient population. Between September 1999 and December 2011, FFR and percent diameter stenosis (DS) as assessed by quantitative coronary angiography were obtained in 2986 patients (n = 4086 coronary stenoses), in whom at least one stenosis was of intermediate angiographic severity. Fractional flow reserve correlated slightly but significantly with DS [−0.38 (95% CI: −0.41; −0.36); P < 0.001]. The sensitivity, specificity, and diagnostic accuracy of a ≥50% DS for predicting FFR ≤ 0.80 were 61% (95% CI: 59; 63), 67% (95% CI: 65; 69), and 0.64 (95% CI: 0.56; 0.72), respectively. In different anatomical settings, sensitivity and specificity showed marked variations between 35 to 74% and 58 to 76%, respectively, resulting in a discordance in 35% of all cases for these thresholds. For an angiographic threshold of 70% DS, the diagnostic performance by the Youden's index decreased from 0.28 to 0.11 for the overall population. The data confirm that one-third of a large patient population shows discordance between angiogram ≥50%DS and FFR ≤0.8 thresholds of stenosis severity. Left main stenoses are often underestimated by the classical 50% DS cut-off compared with FFR. This discordance offers physiologic insights for future trials. It is hypothesized that the discordance between angiography and FFR is related to technical limitations, such as imprecise luminal border detection by angiography, as well as to physiologic factors, such as variable minimal microvascular resistance.

Background—: Fractional flow reserve (FFR) is well established for patients undergoing percutaneous coronary intervention, yet little is known about candidates for coronary artery bypass graft surgery. Methods and Results—: From 2006 to 2010, we retrospectively included in this registry 627 consecutive patients treated by coronary artery bypass graft surgery having at least 1 angiographically intermediate stenosis. In 429 patients, coronary artery bypass graft surgery was based solely on angiography (angiography-guided group). In 198 patients, at least 1 intermediate stenosis was grafted with an FFR ≤0.80 or deferred with an FFR >0.80 (FFR-guided group). The end point was major adverse cardiovascular events at 3 years, defined as the composite of overall death, myocardial infarction, and target vessel revascularization. The rate of angiographic multivessel disease was similar in the angiography-guided and FFR-guided groups (404 [94.2%] versus 186 [93.9%]; P =0.722). In the FFR-guided group, this was significantly downgraded after FFR measurements to 86.4% ( P <0.001 versus before FFR) and was associated with a smaller number of anastomoses (3 [2–3] versus 3 [2–4]; P <0.001) and rate of on-pump surgery (49% versus 69%; P <0.001). At 3 years, major adverse cardiovascular events were not different between the angiography-guided and FFR-guided groups (12% versus 11%; hazard ratio, 1.030; 95% confidence interval, 0.627–1.692; P =0.908). However, the FFR-guided group compared with the angiography-guided group presented a significantly lower rate of angina (Canadian Cardiovascular Society class II–IV, 31% versus 47%; P <0.001). Conclusions—: FFR-guided coronary artery bypass graft surgery was associated with a lower number of graft anastomoses and a lower rate of on-pump surgery compared with angiography-guided coronary artery bypass graft surgery. This did not result in a higher event rate during up to 36 months of follow-up and was associated with a lower rate of angina.

Background—: Fractional flow reserve (FFR) measurement of intermediate coronary stenoses is recommended by guidelines when demonstration of ischemia by noninvasive testing is unavailable. The study aims to evaluate the penetration of this recommendation into current thinking about revascularization strategies for stable coronary artery disease. Methods and Results—: International Survey on Interventional Strategy was conducted via a web-based platform. First, participants’ experiences in interventional cardiology were queried. Second, 5 complete angiograms were provided, presenting only focal intermediate stenoses. FFR and quantitative coronary angiography values were known; however, remained undisclosed. Determination of stenosis significance was asked for each lesion. In cases of uncertainty, the most appropriate adjunctive invasive diagnostic method among quantitative coronary angiography, intravascular ultrasound, optical coherence tomography, or FFR needed to be selected. International Survey on Interventional Strategy was taken by 495 participants who provided 4421 lesion evaluations. In 3158 (71%) decisions, participants relied solely on angiographic appearance that was discordant in 47% with the known FFR, using 0.80 as cutoff value. The use of FFR and imaging modalities was requested in 21% and 8%, respectively. Comparing 4 groups of participants according to the experience in FFR, angiogram-based decisions were less frequent with increasing experience (77% versus 72% versus 69% versus 67%, respectively; P <0.001). As a result, requests for FFR were more frequent (14% versus 19% versus 24% versus 28%, respectively; P <0.001) and rates of discordant decisions decreased (51% versus 49% versus 47% versus 43%, respectively; P <0.022). Conclusions—: The findings confirm that, even when all potential external constraints are virtually eliminated, visual estimation continues to dominate the treatment decisions for intermediate stenoses, indicative of a worrisome disconnect between recommendations and current practice.

Background—: The fractional flow reserve (FFR) value of 0.75 has been validated against ischemic testing, whereas the FFR value of 0.80 has been widely accepted to guide clinical decision making. However, revascularization when FFR is 0.76 to 0.80, within the so-called gray zone, is still debatable. Methods and Results—: From February 1997 to June 2013, all patients with single-segment disease and an FFR value within the gray zone or within the 2 neighboring FFR strata (0.70–0.75 and 0.81–0.85) were included. Study end points consisted of major adverse cardiovascular events (death, myocardial infarction, and any revascularization) up to 5 years. Of 17 380 FFR measurements, 1459 patients were included. Of them, 449 patients were treated with revascularization and 1010 patients were treated with medical therapy. In the gray zone, the major adverse cardiovascular events rate was similar (37 [13.9%] versus 21 [11.2%], respectively; P =0.3) between medical therapy and revascularization, whereas a strong trend toward a higher rate of death or myocardial infarction (25 [9.4] versus 9 [4.8], P =0.06) and overall death (20 [7.5] versus 6 [3.2], P =0.059) was observed in the medical therapy group. Among medical therapy patients, a significant step-up increase in major adverse cardiovascular events rate was observed across the 3 FFR strata, especially with proximal lesion location. In revascularization patients, the major adverse cardiovascular events rate was not different across the 3 FFR strata. Conclusions—: FFR in and around the gray zone bears a major prognostic value, especially in proximal lesions. These data confirm that FFR≤0.80 is valid to guide clinical decision making.