Predictive Value of Silent Myocardial Ischemia for Cardiac Events in Diabetic Patients

Abstract

OBJECTIVE—Silent myocardial ischemia (SMI) in asymptomatic subjects with no history of myocardial infarction or angina is a frequent condition in diabetic patients. The aim of the study was to examine the predictive value of SMI for cardiac events in a multicenter cohort and to determine whether this value is higher in patients with a particular clinical profile.

RESEARCH DESIGN AND METHODS—A total of 370 asymptomatic diabetic patients with at least two additional cardiovascular risk factors was recruited in four departments of diabetology. SMI was assessed by either exercise or dipyridamole single-photon emission–computed tomography myocardial perfusion imaging with thallium-201. If dipyridamole stress was used, an electrocardiogram stress test was performed separately on another day. Follow-up duration was 3–89 months (38 ± 23 months).

RESULTS—There was evidence of SMI in 131 patients (35.4%) on at least one positive noninvasive test. The patients with SMI were significantly older and had significantly higher serum triglycerides and lower HDL cholesterol levels. Cardiac events occurred in 53 patients (14.3%). Major cardiac events (death or myocardial infarction) occurred in 38 patients (10%) and other events (unstable angina, heart failure, or coronary revascularization) occurred in 15 patients. The patients who had cardiac events were older and had higher serum triglyceride levels at baseline. There was a significant association between SMI and cardiac events (hazard ratio 2.79 [95% CI 1.54–5.04]) and in particular major cardiac events (3 [1.53–5.87]). In the patients >60 years of age, the prevalence of SMI was higher (43.4 vs. 30.2% in those <60 years). SMI was associated with a significant risk of cardiac events (2.89 [1.31–6.39]) and in particular major cardiac events (3.66 [1.36–9.87]) for the patients >60 years old but not for those <60 years old.

CONCLUSIONS—In asymptomatic diabetic patients with additional cardiovascular risk factors, SMI is a potent predictor of cardiac events and should be assessed preferably in the patients >60 years of age.