Prevalence and Prognosis of Unrecognized Myocardial Infarction in Asymptomatic Patients With Diabetes: A Two-Center Study With Up to 5 Years of Follow-up.

OBJECTIVE: To determine the prevalence and prognostic significance of unrecognized myocardial infarction (MI) by delayed-enhancement MRI (DE-MRI) in asymptomatic patients with diabetes.

RESEARCH DESIGN AND METHODS: Prospective, two-center study of asymptomatic patients without known cardiac disease ( n = 120). Two prespecified cohorts underwent a research MRI: 1 ) a high-risk group with type 1 diabetes and chronic renal insufficiency ( n = 50) and 2 ) an average-risk group with type 2 diabetes ( n = 70). The primary end point was a composite of all-cause mortality and clinical MI.

RESULTS: Overall, the prevalence of unrecognized MI was 19% by DE-MRI (28% high-risk group and 13% average-risk group) and 5% by electrocardiography. During up to 5 years of follow-up with a total of 460 patient-years of follow-up, the rate of death/MI was markedly higher in patients with diabetes with (vs. without) unrecognized MI (all 44% vs. 7%, high-risk group 43% vs. 6%, and average-risk group 44% vs. 8%; all P < 0.01). After adjustment for Framingham risk score, left ventricular ejection fraction, and diabetes type, the presence of unrecognized MI by DE-MRI conferred an eightfold increase in risk of death/MI (95% CI 3.0-21.1, P < 0.0001). Addition of unrecognized MI to clinical indices significantly improved model discrimination for adverse events (integrated discrimination improvement = 0.156, P = 0.001).

CONCLUSIONS: Unrecognized MI is prevalent in asymptomatic patients with diabetes without a history of cardiac disease and confers a markedly increased risk of death and clinical MI.