Diabetes mellitus is not independently associated with mortality in elderly patients with ST-segment elevation myocardial infarction. Insights from the Codi Infart registry.

Background Diabetes mellitus predicts poorer outcomes in patients with acute coronary syndrome (ACS), but the magnitude of this association in patients at older ages remains controversial. Methods Data were extracted from theCodi Infartdatabase. All consecutive patients with diagnosis of ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) between 2010 and 2015 were included. We assessed the impact of diabetes mellitus on 30-day and one-year mortality in patients aged less than and at least 75 years. Results A total of 12 792 cases were registered, of whom 3023 (23.6%) were aged at least 75 years. About 20% patients had previous diabetes mellitus diagnosis. Patients aged at least 75 years had higher prevalence of comorbidities, higher proportion of heart failure at admission, a more extensive coronary artery disease and significant delay to reperfusion (P< 0.001). Diabetes mellitus was associated with higher 30-day mortality both in young [odds ratio (OR) 1.97, 95% confidence interval (CI): 1.43-2.70] and in elderly patients (OR 1.43, 95% CI: 1.07-1.91). After adjusting for potential confounders, this association remained significant in young patients (OR 1.47, 95% CI: 1.00-2.16,P= 0.047), but not in the elderly (OR 1.14,P= 0.43). Likewise, a crude association between diabetes mellitus and one-year mortality was observed in both groups (young patients: HR = 1.93; 95% CI: 1.51-2.46; older patients: HR = 1.33; 95% CI: 1.08-1.64). However, after adjusting for potential confounders, this association remained significant in younger patients (HR = 1.46; 95% CI: 1.13-1.89;P< 0.001), but not in the elderly (HR = 1.16;P= 0.17). Conclusion A significant proportion of these nonselected patients with STEMI had previous diabetes mellitus. The association between diabetes mellitus and outcomes is different according to age.