Prognostic significance of the hemoglobin A1c level in non-diabetic patients undergoing percutaneous coronary intervention: a meta-analysis

Background The predictive value of hemoglobin A1c (HbA1c) levels in non-diabetic patients with myocardial infarction undergoing percutaneous coronary intervention (PCI) is still controversial. This study aimed to evaluate whether HbA1c levels were independently associated with adverse clinical outcomes in non-diabetic patients with coronary artery disease (CAD) who had undergone PCI by performing a meta-analysis of cohort studies. Methods This meta-analysis included non-diabetic patients with CAD who had undergone PCI. A systematic search for publications listed in the PubMed, Embase, and Cochrane Library databases from commencement to December 2018 was conducted. Studies evaluating the adverse clinical outcomes according to abnormal HbA1c levels in non-diabetic patients diagnosed with CAD who had undergone PCI were eligible. The primary outcomes were long-term all-cause deaths and long-term major adverse cardiac events, and the secondary outcome was short-term all-cause deaths. The meta-analysis was conducted with RevMan 5.3 and Stata software 14.0. Odds ratios (ORs) were pooled using a random or fixed-effects model, depending on the heterogeneity of the included studies. Sub-group analysis or sensitivity analysis was conducted to explore potential sources of heterogeneity, when necessary. Results Six prospective cohort studies involving 10,721 patients met the inclusion criteria. From the pooled analysis, abnormal HbA1c levels were associated with increased risk for long-term all-cause death (OR 1.39, 95% confidence interval [CI] 1.16-1.68,P = 0.001,I-2 = 45%). Sub-group analysis suggested that abnormal HbA1c levels between 6.0% and 6.5% predicted higher long-term major adverse cardiac event (including all-cause deaths, non-fatal myocardial infarction, target lesion revascularization, target vessel revascularization, recurrent acute myocardial infarction, heart failure requiring hospitalization, and stent thrombosis) risk (OR 2.05, 95% CI 1.46-2.87,P < 0.001,I-2 = 0). Contrarily, elevated HbA1c levels were not associated with increased risk of short-term all-cause death (OR 1.16, 95% CI 0.88-1.54,P = 0.300,I-2 = 0). Conclusions An abnormal HbA1c level is an independent risk factor for long-term adverse clinical events in non-diabetic patients with CAD after PCI. Strict control of HbA1c levels may improve patient survival. Further studies in different countries and prospective cohort studies with a large sample size are required to verify the association.