SYNTAX Score and Outcomes in the BARI-2D Study
What is the impact of the SYNTAX score on outcomes and the effectiveness of coronary revascularization compared with medical therapy in the BARI-2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial?
Baseline SYNTAX scores were retrospectively calculated for BARI-2D patients without prior revascularization (N = 1,550) by angiographic laboratory investigators masked to patient characteristics and outcomes. The primary outcome was major cardiovascular events (a composite of death, myocardial infarction, and stroke) over 5 years. Kaplan-Meier cumulative event rates were used to describe outcomes during follow-up. Hazard ratios (HRs) with 95% confidence intervals (CIs) from Cox proportional hazards regression models were used to compare the risk of major cardiovascular events between SYNTAX score groups.
A mid/high SYNTAX score (≥23) was associated with a higher risk of major cardiovascular events (HR, 1.36; CI, 1.07-1.75; p = 0.01). Patients in the coronary artery bypass grafting (CABG) stratum had significantly higher SYNTAX scores: 36% had mid/high SYNTAX scores compared with 13% in the percutaneous coronary intervention (PCI) stratum (p < 0.001). Among patients with low SYNTAX scores (≤22), major cardiovascular events did not differ significantly between revascularization and medical therapy, either in the CABG stratum (26.1% vs. 29.9%, p = 0.41) or in the PCI stratum (17.8% vs. 19.2%, p = 0.84). Among patients with mid/high SYNTAX scores, however, major cardiovascular events were lower after revascularization than with medical therapy in the CABG stratum (15.3% vs. 30.3%, p = 0.02), but not in the PCI stratum (35.6% vs. 26.5%, p = 0.12).
The authors concluded that among patients with diabetes and stable ischemic heart disease, higher SYNTAX scores predict higher rates of major cardiovascular events and were associated with more favorable outcomes of revascularization compared with medical therapy among patients suitable for CABG.
This study reports that the SYNTAX score, a measure of the extent and severity of coronary disease, predicts long-term clinical outcomes in patients with diabetes and coronary disease. A key observation from this study is that higher levels of the SYNTAX score predict particular therapeutic benefit from CABG compared with medical therapy. There was a striking reduction in major cardiovascular events in patients with medium or high SYNTAX scores than in patients with low SYNTAX scores. Ongoing clinical trials such as ISCHEMIA will further help in the selection of patients with stable ischemic heart disease, who are likely to gain the greatest benefit from revascularization in the contemporary era.
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