Prognostic significance of HbA1c in patients with AMI treated invasively and newly detected glucose abnormalities.

Background Glucose abnormalities are frequent comorbidities influencing prognosis in patients with cardiovascular diseases. The objective of this study was to evaluate prognostic role of HbA1c in patients with acute myocardial infarction (AMI) treated invasively, who had newly detected glucose abnormalities. Design Single-centre registry encompassed 2146 survivors of AMI. In all patients without diabetes mellitus (DM), oral glucose tolerance test was performed before hospital discharge and interpreted according to the guidelines. Methods From the study population, two major groups with defined new glucose abnormalities and estimated HbA1c were selected: 457 patients with impaired glucose tolerance (IGT) and 306 patients with newly detected DM (newDM). In each of these groups, the median value of HbA1c was calculated and established as the cut-off point for further analysis. The median HbA1c for IGT group was 5.9% and for newDM was 7.0%. Results Patients with IGT and HbA1c5.9% had significantly lower posthospital mortality (4.5%) than those with HbA1c >5.9% (25.0%; p<0.001). Similarly, patients with newDM and HbA1c 7.0% had lower mortality (6.4%) than those with HbA1c >7.0% (14.3%; p<0.05). Multivariate regression analysis revealed that increase of HbA1c was one of the strongest independent risk factors of death among IGT patients (HR 2.9, 95% CI 2.7-3.1; p<0.001) and newDM (HR 1.53, 95% CI 1.39-1.66; p<0.05). Conclusions Increase of HbA1c in patients with newly detected glucose abnormalities was associated with significantly reduced survival after AMI treated invasively. Moreover, increase of HbA1c in patients with IGT and newDM was one of the strongest independent risk factors of death in these populations.