Quantitative flow ratio as a continuous predictor of myocardial infarction

The quantitative flow ratio (QFR) identifies functionally ischaemic lesions that may benefit more from percutaneous coronary intervention (PCI) than from medical therapy.This study investigated the association between QFR and myocardial infarction (MI) as affected by PCI versus medical therapy.All vessels requiring measurement (reference diameter ≥2.5 mm and existence of at least one stenotic lesion with diameter stenosis of 50-90%) in the FAVOR III China (5,564 vessels) and PANDA-III trials (4,471 vessels) were screened and analysed for offline QFR. The present study reported clinical outcomes on a per-vessel level. Interaction between vessel treatment and QFR as a continuous variable was evaluated for the threshold of 2-year MI estimated by Cox proportional hazards model.Compared with medical therapy at 2 years, PCI reduced the MI risk in vessels with a QFR ≤0.80 (3.0% vs 4.6%) but increased the MI risk in vessels with a QFR>0.80 (3.6% vs 1.2%). Additionally, continuous QFR showed an inverse association with spontaneous MI (hazard ratio [HR] 0.89, 95% confidence interval [CI]: 0.79-0.99; p=0.04) that was reduced by PCI compared to medical therapy (HR 0.26, 95% CI: 0.17-0.40; p<0.0001). The interaction indicated a net benefit for PCI over medical therapy to reduce total MI beginning at QFR ≤0.64.The present study demonstrated a continuous, inverse relationship between the QFR value of a vessel and its subsequent risk for MI, and PCI, compared to medical therapy, reduced this risk beginning at a QFR value of 0.64. These novel findings provide physicians with an angiographic tool for optimising vessel selection for PCI.