Clinical prognostic value of a novel quantitative flow ratio from a single projection in patients with coronary bifurcation lesions treated with the provisional approach.

Background: A novel quantitative flow ratio (μQFR) for bifurcated coronary vessels, derived from a single projection, has been recently reported. Provisional stenting is effective for most bifurcation lesions. However, the clinical value of the side branch (SB) μQFR in patients with coronary bifurcation lesions undergoing provisional stenting remains unclear. Aims: This study aims to determine the clinical predictive value of the SB μQFR after provisional stenting in patients with coronary bifurcation lesions. Methods: Between June 2015 and May 2018, 288 patients with true coronary bifurcation lesions who underwent a provisional approach without SB treatment (including predilation, kissing balloon inflation or stenting) were classified by an SB μQFR <0.8 (n=65) and ≥0.8 (n=223) groups. The primary endpoint was the three-year composite of target vessel failure (TVF), including cardiac death, target vessel myocardial infarction (TVMI), and revascularisation (TVR). Results: Three years after the procedures, there were 43 (14.9%) TVFs, with 19 (29.2%) in the SB μQFR <0.8 and 24 (10.8%) in the SB μQFR ≥0.8 groups (adjusted hazard ratio [HR] 2.45, 95% confidence interval [CI] 1.39-5.54; p=0.003), mainly driven by increased TVMI (16.9% vs 5.4%, adjusted HR 3.29, 95% CI: 1.15-6.09; p=0.030) and TVR (15.4% vs 2.2%, adjusted HR 6.39, 95% CI: 2.04-13.48; p=0.007). Baseline diameter stenosis at the ostial SB and SB lesion length were the two predictors of an SB μQFR <0.8 immediately after stenting the main vessel, whereas previous percutaneous coronary intervention and an SB μQFR <0.8 were the two independent factors of 3-year TVF. Conclusions: An SB μQFR <0.8 immediately after the provisional approach is strongly associated with clinical events. Further randomised studies with large patient populations are warranted.