HbA_1c Levels and Long-Term Mortality in Patients Undergoing Coronary Angiography

Objectives: Previous studies investigating the prognostic value of HbA_1c in patients undergoing coronary angiography reported a mixed pattern of results. Therefore, we aimed to better define the prognostic power of HbA_1c among coronary catheterized patients. Methods: Patients undergoing coronary angiography (n = 3,749) were divided into four groups according to HbA_1c levels (<5, 5-6, 6-7 and >7%). Cox regression models assessed long-term mortality after adjusting for multiple covariates. Results: Baseline clinical profiles differed in HbA_1c groups, with a higher prevalence of comorbidities in the groups with higher HbA_1c levels. Median follow-up was 1,745 days (interquartile range 1,007-2,171). A J-shaped association curve was observed between HbA_1c levels and all-cause mortality rates, with patients in the lowest and highest HbA_1c groups suffering from significantly higher mortality rates compared to in-between groups (hazard ratio 1.9, 95% CI 1.32-2.74, p = 0.001, and hazard ratio 1.58, 95% CI 1.29-1.95, p < 0.001, for the lowest and highest HbA_1c groups, respectively). This association persisted after adjustment for anemia, nutritional status, renal function, cardiovascular risk factors and inflammatory biomarkers. Conclusions: HbA_1c levels <5 or >7% are predictors of all-cause mortality in patients undergoing coronary angiography.