RELATIVE EFFICACY OF MEDICAL THERAPY AND REVASCULARIZATION FOR IMPROVING EXERCISE CAPACITY IN PATIENTS WITH CHRONIC LEFT-VENTRICULAR DYSFUNCTION

Background In patients with left ventricular dysfunction one of the ai ms of therapy may be to improve functional capacity. This study compar ed the improvement of functional capacity in response to medical thera py with that caused by revascularization. Methods Fifty-two patients w ith severe left ventricular dysfunction were divided into groups with ischemic cardiomyopathy undergoing revascularization (group A, n = 20) or incremental medical treatment (group B, n = 16) and a control grou p receiving maximal medical therapy at the start of the study (group C , n = 16). All patients underwent a baseline metabolic exercise test w ith evaluation of peak oxygen consumption and derived exercise capacit y in metabolic equivalents (METS) with standard electrocardiographic a nd hemodynamic monitoring. Therapy was then optimized in the medical t reatment group, whereas the revascularization group underwent coronary bypass grafting. All patients subsequently underwent follow-up metabo lic exercise testing. Results In groups A, B, and C resting left ventr icular ejection fractions were comparable (26% +/- 5%, 25% +/- 7%, and 23% +/- 8%, respectively), as Were results of initial metabolic exerc ise tents (4.7 +/- 0.9 METS, 4.7 +/- 1.4 METS, and 5.2 +/- 1.4 METS). At Follow-up group A improved exercise capacity from 4.7 to 5.6 METS ( p = 0.01). Groups B (4.7 to 5.0 METS) and C (5.2 to 5.6 METS) had no s ignificant improvement. The mean respiratory exchange ratio improved s ignificantly in group A (1.14 to 1.20, p = 0.02), as did left ventricu lar ejection fraction (26% to 31%, p = 0.02). However, neither paramet er changed significantly in groups B or C. Conclusions In patients wit h severe left ventricular dysfunction improvements of exercise capacit y are more marked after coronary revascularization than may be obtaine d after maximization of medical therapy.