False positive stress tests due to undetected left ventricular hypertrophy

Without large vessel coronary artery disease, clinically evident left ventricular hypertrophy (LVH) is an identified cause of ischemic ST segment changes during exercise. The contribution of subclinical LVH to false positive exercise stress test was evaluated from data of 31 patients without electrocardiographic evidence of LVH who underwent concurrent exercise stress testing, M-mode echocardiography and coronary arteriography at Temple University Hospital, Philadelphia, PA, between January, 1976, and December, 1979, and who met echocardiographic criteria for LVH. Using Bayes theorem, the authors found the probability was 0.59 that a patient with electrocardiogram-undetected LVH does not have significant coronary disease with a positive stress test. The probability of normal coronary arteries with a positive stress test in patients without LVH on echocardiogram was 0.24. Inapparent LVH detected by echocardiography increases the likelihood that a patient with a positive stress test does not have coronary disease. Thus, the positive exercise electrocardiogram should be cautiously interpreted in apparently normal patients who have LVH detectable only by echocardiography.