Supersilent Myocardial Ischemia and Risk of All-Cause Mortality in Elderly Patients

Purpose: Elderly patients have a higher prevalence of coronary artery disease but also a higher probability of abnormal perception of angina, and the Duke Treadmill Score failed to show significant prognostic value in these patients. The prevalence and clinical significance of echocardiographic evidence of myocardial ischemia in elderly patients with negative exercise electrocardiograms (i.e., supersilent myocardial ischemia [SSMI]) has not been investigated. Our aim was to evaluate the prevalence, predictors and outcome of SSMI, as assessed by exercise echocardiography, in elderly patients with known or suspected coronary artery disease. Methods: SSMI was defined as the development of exercise-induced wall motion abnormalities in the absence of chest pain or ischemic electrocardiographic changes. A total of 1497 consecutive patients aged ≥65 years (50.8% males) with baseline interpretable electrocardiograms underwent treadmill exercise echocardiography and did not develop chest pain or ischemic electrocardiographic changes during the tests. The increase in wall motion score index from rest to peak exercise (ΔWMSI) was used as a quantifier of the degree of SSMI. The end-point was all-cause mortality. Results: SSMI was evident in 318 patients (20%). In logistic regression analysis, male sex (odds ratio [OR] 2.30, 95% CI 1.73-3.06, p <0.001), diabetes mellitus (OR 1.61, 95% CI 1.17-2.21, p = 0.004), prior myocardial infarction (OR 4.07, 95% CI 3.04-5.46, p <0.001), and resting left ventricular ejection fraction <55% (OR 1.44, IC 1.03-2.03, p = 0.036) remained predictors of SSMI in elderly patients. During an average follow-up of 4.3±3.2 years, 197 patients died. Five-year mortality rate was 16.9% in patients with SSMI vs 11% in those without SSMI (p=0.016). In Cox regression analysis, ΔWMSI remained an independent predictor of mortality (hazard ratio 2.58, 95% CI 1.07-6.23, p=0.03). Conclusions: A significant proportion of elderly patients with known or suspected coronary artery disease have echocardiographic evidence of SSMI in the absence of exercise-induced chest pain or ischemic electrocardiographic changes, which in turn identifies a subgroup of patients at a significantly higher risk of mortality.