EXERCISE TESTING IN PATIENTS WITH ELECTROCARDIOGRAPHIC EVIDENCE OF LEFT-VENTRICULAR HYPERTROPHY

The purpose of this study was to determine the influence of left ventricular hypertrophy, based on electrocardiographic evidence, on the results of exercise thallium testing. Patients with electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH) and suspected of having coronary artery disease underwent exercise thallium testing. Retrospective analysis of 107 consecutive patients with ECG-LVH showed transient myocardial perfusion defects (TMPD) in 12 (11%), indicative of myocardial ischemia; 12 (11%) had fixed myocardial perfusion defects (FMPD), indicative of probably myocardial infarction; 5 had TMPD plus FMPD (5%), and scan results for 78 were normal (73%). In patients with ECG-LVH, additional ST changes were observed in 76% and chest pain in 7% of patients with ECG-LVH. In a matched comparison group of 255 patients not prescreened for ECG-LVH, TMPD was observed in 20%, FMPD in 16%, and TMPD plus FMPD in 26% of patients, and normal results were found in 38%. Electrocardiographic changes were found in 49% and chest pain in 20%. Hemodynamic responses to exercise were comparable between subgroups. Lung thallium uptake was quantified as the lung-to-heart thallium activity ratio (L-H) on the immediate exercise anterior planar images. In controls, a significant increase in L-H was observed in patients with TMPD and TMPD plus FMPD. This was not observed in patients with ECG-LVH, possibly because of elevated thallium myocardial activity as a result of increased left ventricular mass. The conclusion is that patients with ECG-LVH often had normal perfusion scan results (73%) on exercise despite a high incidence of additional ECG changes (76%). This provides further evidence for diagnostic superiority of exercise thallium testing in patients with ECG-LVH. However, caution should be exercised in the evaluation of L-H as an index of left ventricular function in patients with ECG-LVH.