Silent Myocardial Ischemia in Asymptomatic Patients with Multiple Coronary Risk Factors

Myocardial ischemia which occurs in the absence of chest pain or its equivalents (silent myocardial ischemia) is common in patients with coronary artery disease. Silent myocardial ischemia may also be found in asymptomatic patients, particularly those with underlying risk factors. It is important for physicians to identify the existence of silent myocardial ischemia because it is predictive of increased cardiac risk. Objective: To evaluate the frequency and characteristics of silent myocardial ischemia in asymptomatic patients with multiple coronary risk factors ("high coronary risk" patients). Methods: Study group consisted of 360 male pts (age from 35 to 70 years) with multiple coronary risk factors free of previously diagnosed coronary artery disease. In study pts the most frequent risk factors for coronary artery disease were arterial hypertension (74%) and cigarette smoking (60%). In all pts maximal, or ST segment depression of ≥ 0.2 mV or symptom-limited exercise test was performed. In those with ST-segmant depression on exercise electrocardiogram, stress echocardiography was additionally performed in order to confirm myocardial ischemia. Results: Out of 360 patients 290 (81%) patients had neither ST-segment depression nor anginal pain during exercise stress testing, 52 (14%) patients had ischemic type of ST-segment depression on exercise electrocardiogram without chest pain and 18 (5%) patients had ischemic ST-segment depression and the first occurrence of chest pain (symptomatic myocardial ischemia). All patients with symptomatic myocardial ischemia had an echocardiographic marker for ischemia but out of 52 patients with asymtpomatic ST-segment depression 43 patients had echo markers for ischemia (silent miocardial ischemia), while in 9 patients stress echocardiography was without regional wall motion abnormality (false positive exercise electrocardiogram). Thus both types of myocardial ischemia were recorded in 61 (17%) "high coronary risk" patients (12% silent and 5% symptomatic myocardial ischemia). There were no significant difference in regard to magnitude and duration of ST-segment depression and exercise tolerance between patients with symptomatic and silent myocardial ischemia, but wall motion score index was bigger in patients with symptomatic than in those with silent myocardial ischemia (P<0.01). Conclusion: This study showed that in 12% of asymptomatic "high coronary risk" patients silent myocardial ischemia during exercise test was found. There were no differences between two types of myocardial ischemia in the exercise electrocardiogram but symptomatic ischemia had a higher degree of wall motion abnormality on stress echo than silent myocardial ischemia.