Flow Reserve: Linking Physiologic Severity to Clinical Outcomes

Study Question:

What is the relationship between fractional flow reserve (FFR) numeric value and prognosis?

Methods:

A meta-analysis of both study-level and patient-level data investigated prognosis after FFR measurement. An interaction term between FFR and revascularization status allowed for an outcomes-based threshold. Due to variable length of follow-up, the authors primarily performed a time-to-event analysis using a Cox proportional hazards model.

Results:

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 of 0.75-0.80, 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, 0.80-0.93; 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.

Conclusions:

The authors concluded that FFR demonstrates a continuous and independent relationship with subsequent outcomes, modulated by medical therapy versus revascularization.

Perspective:

This study reports that FFR provides a continuous and independent marker of subsequent major adverse cardiac events (MACE), as modulated by treatment (medical therapy vs. revascularization) in a broad range of clinical scenarios. Lesions with lower FFR values appear to receive larger absolute benefits from percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Measurement of FFR immediately after PCI also shows an inverse gradient of risk, likely from residual diffuse disease. Overall, an FFR-guided revascularization strategy significantly reduces MACE and increases freedom from angina with less PCI or CABG than an anatomy-based strategy.

Source: www.cardiosource.org