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 the Codi Infart database. 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.