Objectives: To evaluate the contribution of chronic total occlusion (CTO)-related SYNTAX score (SS) to the overall SS for patients with CTO and compare the traditional SS to a simplified variant. The SS algorithm assigns CTO lesions a greater weight (5× points) than non-CTO lesions (50% to <100% diameter stenosis; 2× points).
Methods: We calculated the SS and the simplified SS (2× points also to CTO lesions) for 4356 patients from the angiographic substudy of the Acute Catheterization and Urgent Intervention Triage StrategY (ACUITY) trial. We compared the association between SS and 1-year mortality and major adverse cardiac events for patients with and without a CTO. We also compared the simplified SS with the traditional SS.
Results: The median SS was 20 (interquartile range, 13-27.5) for patients with a CTO and 8 (interquartile range, 2-16) for patients without a CTO. For patients with a CTO, the CTO lesion(s) contributed 67 ± 26% of the total SS. The simplified SS reclassified 187/603 (31.0%) of patients with a SS >22 to a SS ≤22. The traditional SS did not improve discrimination indices for predicting outcomes compared with the simplified SS.
Conclusions: CTO lesions contribute considerably to the total SS in patients with a CTO. A simplified SS that does not differentiate between CTO and non-CTO lesions appeared equivalent to the traditional SS for risk prediction, but reclassified a substantial proportion of patients to a SS ≤22 and may impact choice of revascularization strategy for patients with complex coronary artery disease involving a CTO lesion.