PREVALENCE OF AND VARIABLES ASSOCIATED WITH SILENT-MYOCARDIAL-ISCHEMIA ON EXERCISE TL-201 STRESS-TESTING

The prevalence of silent myocardial ischemia was prospectively assessed in a group of 103 consecutive patients (mean age 59 ± 10 years, 79% male) undergoing symptom-limited exercise thallium-201 scintigraphy. Variables that best correlated with the occurance of patients ischemia by quantitative scintigraphic criteria were examined. Fifty-nine patients (57%) had no angina on exercise testing. A significantly greater persent of patients with silent ischemia than of patients with angina had a recent myocardial infarction (31% versus 7%, P < 0.01), had no prior angina (91% versus 64%, p < 0.01), had dyspnea as an exercise test end point (56% versus 35%, p < 0.05) and exhibited redistribution defects in the supply regions of the right and circumflex coronary arteries (50% versus 35%, p < 0.05). The group with exercise angina had more ST depression (64% versus 41%, p < 0.05) and more patients with four or more redistribution defects. However, there was no difference between the two groups with respect to mean total thallium-201 perfusion score, number of redistribution defects per patient, multivessel thallium redistribution pattern or extent of angiographic coronary artery disease. There was also no difference between the silent ischemia and angina groups with respect to antianginal drug, usage, prevalence of diabetes mellitus, exercise duration, peak exercise heart rate, peak work load, peak double (rate-pressure) product and percent of patients achieving ≥85% of maximal predicted heart rate for age. Thus, in this study group, there was a rather high prevalence rate of silent ischemia (57%) by exercise thallium-201 criteria. Patients with silent ischemia and those with exercise angina had comparable 1) exercise tolerance and hemodynamics, 2) extent of angiographic coronary artery disease, and 3) extent of exercise-induced hypoperfusion. Finally, more patients with recent infarction had silent ischemia than had exercise angina. © 1990.