Silent myocardial infarction and its prognosis in a community-based cohort of Type 2 diabetic patients: the Fremantle Diabetes Study

Aims/hypothesis. Our study investigated the prognosis of Type 2 diabetic patients with silent myocardial infarction in a community-based cohort. Methods. We analysed data from 1269 patients with Type 2 diabetes mellitus from a community-based observational study of diabetes care, control and complications. Silent myocardial infarction was defined as Q waves (Minnesota codes 1.1, 1.2) on a baseline electrocardiogram in the absence of a history or symptoms of CHD. Results. Silent myocardial infarction was present in 3.9% of patients, or 44% of all Q-wave myocardial infarctions. The patients were subdivided into those with (i) no clinical or Q-wave evidence of myocardial infarction (Group 1), (ii) silent myocardial infarction (Group 2), (iii) self-reported CHD but no Q waves (Group 3), and (iv) self-reported CHD and Q waves (Group 4). Compared to Groups 3 and 4, Group 2 patients were more likely to be women, less likely to have smoked, and had higher serum HDL-cholesterol concentrations and higher blood pressure. Over an average of seven years, and after adjusting for other independent predictors of death, all-cause and CHD mortality were similar in Groups 1 and 2 and greater (twofold for all-cause and fourfold for CHD mortality) in Groups 3 and 4. Conclusions/interpretation. Silent myocardial infarction is common in Type 2 diabetes and has a prognosis similar to that in patients without a history of CHD or Q waves.