School of Medicine

Background: Heart disease remains the leading cause of mortality in the United States and many experience no symptoms prior to a cardiovascular disease (CVD) death. We asked if Silent Myocardial Ischemia (Silent MI) predicts CVD mortality among community-dwelling older adults and if diabetes status impacts this association. Methods and Results: We analyzed 1882 participants from the 1984-1987 Rancho Bernardo Study clinic visit who were ≥50 years old with no history of coronary heart disease (defined by prior revascularization, myocardial infarction, or angina). We detected Silent MI using ischemic resting changes on 12-lead electrocardiogram (one or more: major or small Q or QS wave, complete left bundle-branch block, ST depression, or T wave items). We determined diabetes status by oral glucose tolerance test and CVD death (ICD-9 codes 390.0-459.0) through 2007 by death certificate. Kaplan-Meier analysis showed reduced mean survival times in participants with Silent MI (16.4 versus 19.4 years, p<0.001) or diabetes (17.4 versus 19.1 years, p=0.008). In Cox proportional hazards models, Silent MI was independently associated with CVD death (HR 1.58, 95% CI 1.29-1.95) after adjusting for age, waist hip ratio, systolic blood pressure, exercise, sex, and diabetes. For participants with diabetes, Silent MI did not predict CVD death (HR 1.34, 95% CI 0.826-2.17). Conclusions: Silent MI is independently associated with CVD death in older adults, and not significantly associated for those with diabetes. Therefore, Silent MI identified by resting ECG remains an important predictor of CVD mortality regardless of other risk factors in those without diabetes.