Silent ischemia during daily life is an independent predictor of mortality in stable angina

Abstract

We prospectively examined the prognostic significance of silent myocardial ischemia detected by ambulatory electrocardiogram (ECG) monitoring during daily life in 107 patients with long-term stable angina who were symptomatically controlled on conventional antianginal agents. Forty-six patients (group 1) demonstrated one or more episodes (87% silent) of myocardial ischemia; the remaining 61 patients (group 2) had no ischemic ST segment changes. During the mean follow-up period of 23±8 months, 11 cardiac deaths (five sudden and six nonsudden) occurred in group 1, and five cardiac deaths (all nonsudden) occurred in group 2. Kaplan-Meier survival analysis between the groups confirmed that patients with silent ischemia (group 1) had worse prognoses during the follow-up period (p=0.023). Although the higher incidence of hypertension, smoking, hypercholesterolemia, and diabetes in our patients might reflect a more sickly population of stable angina patients, the multivariate Cox's hazard function analysis of these and other variables including Q waves on ECG, exercise parameters, and ambulatory ECG findings revealed presence of silent ischemia during daily life as the most powerful and independent predictor of cardiac mortality (p=0.01). These data indicate that, in such patients with stable angina, silent myocardial ischemia occurs frequently during treatment with conventional antianginal drugs and identifies a subset of patients who are at high risk of cardiac death.