Prognostic Implication of Functional Incomplete Revascularization and Residual Functional SYNTAX Score in Patients With Coronary Artery Disease

Objectives: The aim of this study was to investigate the prognostic implication of functional incomplete revascularization (IR) and residual functional SYNTAX (Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery) score (rFSS) in comparison with 3-vessel fractional flow reserve (FFR) and residual SYNTAX score. Background: IR is associated with poor clinical outcomes in patients who underwent percutaneous coronary intervention. Methods: A total of 385 patients who underwent 3-vessel FFR measurement after stent implantation were included in this study. The rFSS was defined as residual SYNTAX score measured only in vessels with FFR ≤0.8. The study population was divided into the functional IR group (rFSS ≥1) and the functional complete revascularization (CR) group (rFSS = 0). The primary outcome was major adverse cardiac events (MACEs; a composite of cardiac death, myocardial infarction, and ischemia-driven revascularization) at 2 years. Results: Functional CR was achieved in 283 patients (73.5%). At 2-year follow-up, the functional IR group showed a significantly higher risk for MACEs (functional IR vs. CR, 14.6% vs. 4.2%; hazard ratio: 4.09; 95% confidence interval: 1.82 to 9.21; p < 0.001) than the functional CR group. In a multivariate-adjusted model, functional IR was an independent predictor of MACEs (adjusted hazard ratio: 4.17; 95% confidence interval: 1.85 to 9.44; p < 0.001). The rFSS showed a significant association with estimated 2-year MACE rate (hazard ratio: 1.09 per 1-U increase; 95% confidence interval: 1.02 to 1.17; p = 0.018). When added to clinical risk factors, rFSS showed the highest integrated discrimination improvement value for MACEs (3.5%; p = 0.002) among 3-vessel FFR, residual SYNTAX score, and rFSS. Conclusions: Patients with functional IR showed significantly higher rate of 2-year MACEs than those with functional CR. A combined anatomic and physiological scoring system (rFSS) after stent implantation better discriminated the risk for adverse events than anatomic or physiological assessment alone.