FFR vs. Angiography: Improving PCI Outcomes & Assessing Stenosis Accuracy

Long-term data from the FAME 2 trial indicates that guiding percutaneous coronary intervention (PCI) with fractional flow reserve (FFR) significantly reduces the risk of major adverse cardiac events compared to medical therapy alone, and potentially offers advantages over PCI guided by standard angiography, according to research published in Nature.

The trial, which followed 748 patients for a median of 11.2 years, demonstrated that FFR-guided PCI reduced the risk of a composite outcome of death, myocardial infarction, or urgent revascularization. Specifically, the primary endpoint occurred in 33.6% of patients in the PCI group versus 41.3% in the medical therapy group, resulting in a win ratio of 1.25 in favor of PCI (95% confidence interval 1.01–1.56, P = 0.043). This translates to a number needed to treat of 17 patients to prevent one adverse event.

FFR assesses the hemodynamic significance of coronary artery stenosis – narrowing of the arteries – by measuring the pressure difference across a blockage. This provides a more accurate assessment than relying solely on angiography, which provides a visual image of the artery but doesn’t directly measure blood flow impact. The FAME 2 trial focused on patients with stable coronary artery disease and hemodynamically significant stenoses, defined as an FFR of 0.80 or less.

The long-term benefits observed were largely driven by a reduction in urgent revascularizations. Whereas there was no statistically significant difference in all-cause mortality between the two groups (win ratio 0.88, 95% CI 0.66–1.17), FFR-guided PCI showed a benefit in reducing myocardial infarction (win ratio 1.50, 95% CI 0.98–2.31) and a substantial reduction in the need for urgent revascularization (win ratio 4.57, 95% CI 2.53–8.24).

A related emerging technique, angiography-derived fractional flow reserve (Angio-FFR), aims to estimate FFR using standard angiography images and computational fluid dynamics, potentially eliminating the need for a pressure wire or administering hyperaemic agents. Research suggests Angio-FFR demonstrates fine correlation with invasive, wire-based FFR assessments.

The findings reinforce the growing body of evidence supporting physiological assessment of coronary artery disease before intervention. Previous studies have indicated that revascularization decisions based on FFR or intravascular ultrasonography yield superior clinical outcomes compared with PCI guided by angiography alone, though direct comparisons of these approaches are ongoing.