Long-term association of post stent fractional flow reserve with clinical events

Abstract Background Low fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) is associated with procedural factors in the stented segment and residual disease in the non-stented segment. Even the prognostic value of post-PCI FFR has been reported, its long-term clinical relevance has not been thoroughly investigated. Purpose We sought to investigate the long-term prognostic value of post-PCI FFR and its relative significance on future events in stented and non-stented segments. Methods The International Post-PCI FFR extended registry (NCT04684043) followed the 2,200 patients who underwent PCI and measured post-PCI FFR between June 2011 and May 2018. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction (TVMI), and target vessel revascularization (TVR) at 5 years. The secondary outcomes were a composite of cardiac death or TVMI at 5 years. Results The median value of post-PCI FFR of target vessels was 0.89 (IQR 0.84-0.93). The optimal cut-off value of post-PCI FFR for predicting TVF was 0.81, and that for predicting cardiac death or TVMI was 0.76, respectively. The cumulative incidence of TVF was significantly higher in the low post-PCI group (20.5%) than in the high post-PCI FFR group (10.3%) (adjusted hazard ratio [HR] 2.11, 95% confidence interval [CI] 1.56-2.86, p<0.001). The cumulative incidence of cardiac death or TVMI was also significantly higher in the low post-PCI FFR group (7.3%) than in the high post-PCI FFR group (3.2%) (adjusted HR 2.34, 95% CI 1.12-4.91, p=0.024). Landmark analysis at 2 years showed that the impact of post-PCI FFR on TVF was consistently found during the first 2 years (adjusted HR of low post-PCI FFR 2.22, 95% CI 1.54-3.21, p<0.001) and thereafter (adjusted HR of low post-PCI FFR 1.96, 95% CI 1.14-3.36, p<0.001). However, the impact of post-PCI FFR on cardiac death or TVMI was more significant after 2 years of follow-up (adjusted HR of low post-PCI FFR 2.01, 95% CI 0.66-6.11, p=0.217 for the first 2 years and adjusted HR of low-post PCI FFR 2.81, 95% CI 1.04-7.60, p=0.042). The cumulative incidence of TVR was 9.5% for 5 years, and 61.0% of TVRs occurred in the stented segment. However, the proportion of TVRs in the non-stented segment increased along with the decrease of post-PCI FFR (35.3% in post-PCI FFR more than 0.90, 34.1% in post-PCI FFR 0.81-0.90, 43.8% in post-PCI FFR 0.71-0.80, and 66.7% in post-PCI FFR 0.70 and less than 0.70, p-for trend<0.001). Conclusions The long-term outcome results of the Internation Post-PCI FFR Extended registry showed that the prognostic impact of post-PCI FFR on TVF was consistently found along with the follow-up. However, that of post-PCI FFR on cardiac death or TVMI was more prominent during the late period of follow-up. In addition, clinical event distribution was different according to post-PCI FFR values.