Hemoglobin A_1c and Cardiovascular Outcomes Following Percutaneous Coronary Intervention: Insights From a Large Single-Center Registry

Objectives: The aim of this study was to evaluate post–percutaneous coronary intervention (PCI) outcomes in relation to pre-procedural glycated hemoglobin (HbA_1c) levels from a large, contemporary cohort. Background: There are limited data evaluating associations between HbA_1c, a marker of glycemic control, and ischemic risk following PCI. Methods: All patients with known HbA_1c levels undergoing PCI at a single institution between 2009 and 2017 were included. Patients were divided into 5 groups on the basis of HbA_1c level: ≤5.5%, 5.6% to 6.0%, 6.1% to 7.0%, 7.1% to 8.0%, and >8.0%. The primary endpoint was major adverse cardiac events (MACE), a composite of all-cause death or myocardial infarction (MI), at 1-year follow-up. Results: A total of 13,543 patients were included (HbA_1c ≤5.5%, n = 1,214; HbA_1c 5.6% to 6.0%, n = 2,202; HbA_1c 6.1% to 7.0%, n = 4,130; HbA_1c 7.1% to 8.0%, n = 2,609; HbA_1c >8.0%, n = 3,388). Patients with both low (HbA_1c ≤5.5%) and high (HbA_1c >8.0%) levels displayed an increased risk for MACE compared with those with values between 6.1% and 7.0%. Excess risk was driven primarily by higher rates of all-cause death among those with low HbA_1c levels, while higher values were strongly associated with greater MI risk. Patterns of risk were unchanged among patients with serial HbA_1c levels and persisted after multivariate adjustment. Conclusions: Among patients undergoing PCI, pre-procedural HbA_1c levels display a U-shaped association with 1-year MACE risk, a pattern that reflects greater risk for death in the presence of low HbA_1c (≤5.5%) and higher risk for MI with higher values (>8.0%).