Background: Diabetes mellitus (DM) associates with complex coronary artery disease (CAD), what in turn translates into increased morbidity from cardiovascular disease. The SYNTAX Score (SS) is an anatomical based tool for objectively determining the complexity of CAD and guiding decision-making between CABG and PCI. Nonetheless, few studies have evaluated the SS in DM patients for choosing between CABG and PCI revascularization strategy, and its role in predicting future cardiovascular events.
Objectives: To evaluate the role of SS in predicting major adverse cardiovascular events (MACCE) in PCI and CABG groups in DM with multivessel CAD in FREEDOM.
Methods: FREEDOM was a randomized trial that assigned patients with DM and multivessel CAD to undergo either PCI with drug-eluting stents or CABG. The SS for each patient was calculated retrospectively by a core laboratory. MACCE was defined by death from any cause, myocardial infarction, stroke and need for repeat revascularization. Multivariate analysis was conducted using Cox regression modelling.
Results: FREEDOM included 1900 patients randomized to PCI (953) or CABG (947). The mean Syntax Score were similar in PCI (26.2±8.4) and CABG (26.11±8.8) groups (p=0.67). In multivariate analysis of the PCI cohort, left ventricular ejection fraction (LVEF) < 40%, insulin dependent DM, Creatinine Clearance <60ml/min, and SS (HR=1.02, CI 95% 1.00 to 1.03, p=0.014) were independent predictors of MACCE at 5-years. In the CABG group, age > 70 years, left ventricular ejection fraction (LVEF) < 40%, insulin dependent DM, Creatinine Clearance < 60 ml/min but not SS were independent predictors of MACCE at 5-years. LDL cholesterol ≤ 100 mg/dL was considered a protective factor for MACCE in the CABG group. There was a higher incidence of MACCE in PCI patients with low, intermediate and high SS compared to those who underwent CABG (36.6% vs 25.9% with low SS category , p=0.02 ; 43.9% vs 26.8% with intermediate SS category, p<0.001; 48.7% vs 29.7% with high SS, p=0.003).
Conclusions: In DM patients the complexity of CAD evaluated by the SS is a modest independent risk factor for MACCE only in patients undergoing PCI. In DM with multivessel CAD, the incidence of MACCE is higher for the PCI treatment strategy in all Syntax scores categories.