Silent versus symptomatic dipyridamole-induced ischemia after myocardial infarction: Clinical and prognostic significance

Abstract

The prevalence and prognostic significance of silent myocardial ischemia were prospectively assessed in 217 patients (mean age 57 ± 9 years, 83% male) recovering from a first uncomplicated acute myocardial infarction and undergoing a dipyridamole echocardiography test before hospital discharge. Clinical, angiographic, exercise electrocardiographic (ECG) and dipyridamole echocardiographic variables were also examined. Of the 217 patients, 89 had no echocardiographically proved dyssynergy after dipyridamole, whereas 128 had dipyridamole-induced wall motion abnormalities that were silent in 94 (Group I) and symptomatic in 34 (Group II).There was no intergroup difference with respect to dipyridamole time (i.e., the time from onset of the test to frank dyssynergy: 7 ± 3 vs. 8 ± 3 min; p = NS); prevalence of inferior myocardial infarction (69% vs. 71%; p = NS); ischemic ECG changes during the test (83% vs. 71%; p = NS); diabetes (8.5% vs. 6%; p = NS); ongoing medical therapy; multivessel disease (57% vs. 56%; p = NS); and baseline left ventricular ejection fraction (57 ± 13% vs. 57 ± 10%; p = NS). There was also no significant difference between Group I and Group II with respect to watt motion score index at peak dipyridamole effect (1.77 ± 0.39 vs. 1.78 ± 0.36; p = NS).Patients were followed up for 24 ± 4 and 25 ± 5 months, respectively (p = NS). Life table analysis revealed no difference in unstable angina, reinfarction and death between the two groups. A Cox survival analysis identified a positive echocardiogram after dipyridamole administration as the best predictor of cardiac events (chi-square = 9.1; p < 0.003), whereas dipyridamole-induced chest pain showed no independent predictive value (chisquare = 2.7; p = NS).Thus, patients with silent ischemia and symptomatic ischemia had comparable 1) severity of dipyridamole-induced ischemia (as assessed by dipyridamole time and extent of wall motion abnormalities), 2) extent of angiographic coronary artery disease, and 3) incidence of critical cardiac events.