Prognostic Value of Quantitative Flow Ratio Based Functional SYNTAX Score in Patients With Left Main or Multivessel Coronary Artery Disease

Background: The potential impact of quantitative flow ratio (QFR) based functional Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) score (FSS) on prognostication and revascularization strategy choice has not been fully investigated, and the discriminant ability of FSS needs further validation.

Methods: QFR was retrospectively analyzed in left main or patients with multivessel coronary artery disease from the PANDA III trial. A total of 607 patients with analyzable QFR in all vessels were included. FSS was counted by summing the individual scores only in ischemia-producing lesions (vessel QFR ≤0.8). Patients were stratified according to tertiles of SYNTAX score (SS), and 3 groups of FSS were divided by the same cutoff score. The primary end point was 2-year major adverse cardiac events (a composite of cardiac death, any myocardial infarction, or ischemia-driven revascularization).

Results: After calculating the FSS, 16% (96/607) of study patients moved from higher-risk group by SS to lower-risk group. In the low, intermediate, and high FSS group, the cumulative incidence of 2-year major adverse cardiac events was 9.1%, 13.5%, and 22.3% (=0.0004), and the rate of a composite of cardiac death or myocardial infarction (3.8%, 7.3%, and 13.7%, =0.0006) was also increased. Compared with SS, FSS significantly improved risk classification and prognostication (area under the curve of the receiver-operating characteristics 0.65 versus 0.62, =0.0009). Moreover, 6% (38/607) of patients, for whom coronary artery bypass grafting would be recommended according to SS, converted to favor percutaneous coronary intervention after FSS calculation. After multivariate adjustment, FSS was an independent predictor of 2-year major adverse cardiac events (adjusted hazard ratio, 1.05 [95% CI, 1.02-1.07]; =0.0001).

Conclusions: Among patients with left main or multivessel coronary artery disease, FSS showed applicability in prognostication and revascularization strategy choice. An improved scoring system combining anatomy and physiology (FSS) discriminated the risk of adverse events modestly better than anatomic assessment (SS) alone. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02017275. Graphic Abstract: A graphic abstract is available for this article.