Prevalence and prognosis value of silent myocardial ischemia in patients with acute myocardial infarction

pp 109-116

Abstract

To asses the prevalence and prognosis value of silent residual myocardial ischemia patients with acute myocardial infarction (AMI) underwent atrial pacing before hospital discharge (mean 16.5 days). The testing was performed in 121 patients, mean 55.5 years old, 101 men, 20 women, 65 with inferior localization, 51 with anterior and 5 indeterminated, 107 with Q infarction and 14 with non Q (Table 1). Atrial pacing induced myocardial ischemia (S T elevation  ≥ 0.1 mV) in 42 patients (34.7%), was negative in 60 (49.5%) and insufficient in 19 (15.7%). Among the 42 patients to whom ischemia with atrial pacing was induced, 27 (64 %) did not have angina (silent ischemia), while 15 (36 %) had anginal pain (symptomatic) (Figure 2). We found out that out of 51 anterior infarcts pacing induced ischemia only in 12 (23.5%), while out of 65 inferior infarcts pacing was positive in 28 (43 %) (P < 0.01) (Table 3). More patients with positive than with negative pacing were taking beta-bloquers (Table 2), but no differences were found between patients with silent or symptomatic pacing induced ischemia, regarding age, sex, localization of AMI, diabetes, severity of coronary disease or treatment received. Among 121 patients we lost contact with 3 of them during the follow-up of a mean of 27 months (6-43); out of 41 patients with positive pacing 20 presented major events (48.7%); 3 reinfarcted, 6 died of cardiac death and 11 underwent coronary revascularization while, out of 59 negative pacing only 11 presented complication (18.6%) (P < 0.01); 1 patient had recurrent infarction, 3 died and 7 underwent by-pass surgery (Tables 5 and 6), but incidence of major coronary events was not significantly different between patients with painful or painless ischemia. These results have indicated that myocardial ischemia silent or symptomatic, induced by atrial pacing is not an uncommon finding soon after a myocardial infart. The demonstration of ischemia represent a worse prognosis but this is independent of symptoms.