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

The purpose of this study was to determine the influence of left ventr icular hypertrophy, based on electrocardiographic evidence, on the res ults of exercise thallium testing. Patients with electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH) and suspected of ha ving coronary artery disease underwent exercise thallium testing. Retr ospective analysis of 107 consecutive patients with ECG-LVH showed tra nsient 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 F MPD (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 pati ents 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 foun d in 38%. Electrocardiographic changes were found in 49% and chest pai n in 20%. Hemodynamic responses to exercise were comparable between su bgroups. Lung thallium uptake was quantified as the lung-to-heart thal lium activity ratio (L-H) on the immediate exercise anterior planar im ages. In controls, a significant increase in L-H was observed in patie nts with TMPD and TMPD plus FMPD. This was not observed in patients wi th 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%) o n exercise despite a high incidence of additional ECG changes (76%). T his provides further evidence for diagnostic superiority of exercise t hallium testing in patients with ECG-LVH. However, caution should be e xercised in the evaluation of L-H as an index of left ventricular func tion in patients with ECG-LVH.