Prognostic significance of QFR-based SYNTAX score in patients with coronary artery disease: a systematic review and meta-analysis

Abstract Background The Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) score (SS) is a well-established angiographic scoring system which allows to assess lesion characteristics, as well as to predict cardiovascular events in patients undergoing coronary revascularization. However, as recent evidence document the superiority of physiology-based revascularization, over angiography-based revascularization, functional parameters have been added to SS, therefore creating the functional SS (FSS). Quantitative flow ratio (QFR) is a novel, non-invasive method for accurately calculating a lesion’s fractional flow reserve, with good diagnostic accuracy when compared to invasive indices in identifying significant epicardial stenoses. Purpose The aim of this systematic review and meta-analysis is to evaluate the prognostic effect of the QFR-based FSS (QFRFSS) in patients undergoing percutaneous coronary interventions. Methods We performed a systematic search in 3 different databases (MEDLINE/PubMed, Web of Science and Scopus). After selecting all appropriate studies according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a random effect meta-analysis was performed. Results A total of 4 studies and 1,315 patients were included, with a mean follow-up of 22.5 months. Among included individuals, a low QFRFSS (13) was present in 563 patients (42.8%), an intermediate QFRFSS in 411 (31.3%) and a high QFRFSS in 343 patients (25.9%). Comparing the low with the high cohorts, patients with low QFRFSS has significantly lower risk for major adverse cardiovascular events Risk Ratio (RR): 0.40; 95% Confidence Interval (CI): 0.23-0.70, cardiovascular morality (RR: 0.29; 95%CI: 0.10-0.84), as well as recurrent myocardial infarction (RR: 0.46; 95%CI: 0.25-0.86). However, a non-significant trend was found regarding ischemia-driven revascularization events (RR: 0.74; 95%CI: 0.44-1.27). Similarly, a significant increase of cardiovascular events for those with high QFRFSS was found when comparing intermediate with high QFRFSS, with the exception of cardiovascular mortality. Finally, no significant differences were found in the comparison of the low and intermediate QFRFSS cohorts. Conclusion The presence of a high QFRFSS score is significantly associated with worse cardiovascular outcomes in patients with coronary artery disease. Implementing physiology along with anatomical lesion assessment has the potential to enhance the selection of revascularization strategies in the everyday practice.