Predictive Value of Combining the Ankle-Brachial Index and SYNTAX Score for the Prediction of Outcome After Percutaneous Coronary Intervention (from the SHINANO Registry)

Abstract

The Synergy Between PCI With TAXUS and Cardiac Surgery (SYNTAX) score is effective in predicting clinical outcome after percutaneous coronary intervention (PCI). However, its prediction ability is low because it reflects only the coronary characterization. We assessed the predictive value of combining the ankle-brachial index (ABI) and SYNTAX score to predict clinical outcomes after PCI. The ABI-SYNTAX score was calculated for 1,197 patients recruited from the Shinshu Prospective Multi-center Analysis for Elderly Patients with Coronary Artery Disease Undergoing Percutaneous Coronary Intervention (SHINANO) registry, a prospective, observational, multicenter cohort study in Japan. The primary end points were major adverse cardiovascular and cerebrovascular events (MACE; all-cause death, myocardial infarction, and stroke) in the first year after PCI. The ABI-SYNTAX score was calculated by categorizing and summing up the ABI and SYNTAX scores. ABI ≤ 0.49 was defined as 4, 0.5 to 0.69 as 3, 0.7 to 0.89 as 2, 0.9 to 1.09 as 1, and 1.1 to 1.5 as 0; an SYNTAX score ≤ 22 was defined as 0, 23 to 32 as 1, and ≥ 33 as 2. Patients were divided into low (0), moderate (1 to 2), and high (3 to 6) groups. The MACE rate was significantly higher in the high ABI-SYNTAX score group than in the lower 2 groups (low: 4.6% vs moderate: 7.0% vs high: 13.9%, p = 0.002). Multivariate regression analysis found that ABI-SYNTAX score independently predicted MACE (hazards ratio 1.25, 95% confidence interval 1.02 to 1.52, p = 0.029). The respective C-statistic for the ABI-SYNTAX and SYNTAX score for 1-year MACE was 0.60 and 0.55, respectively. In conclusion, combining the ABI and SYNTAX scores improved the prediction of 1-year adverse ischemic events compared with the SYNTAX score alone.