EFFECT OF EXERCISE TRAINING ON MYOCARDIAL REMODELING IN PATIENTS WITHREDUCED LEFT-VENTRICULAR FUNCTION AFTER MYOCARDIAL-INFARCTION - APPLICATION OF MAGNETIC-RESONANCE-IMAGING

Background There are conflicting reports on the effects of training on the remodeling process in post-myocardial infarction patients with ve ntricular damage. Methods and Results Twenty-five patients with reduce d ventricular function (mean ejection fraction, 32.3+/-6%) after an an teroseptal or inferolateral myocardial infarction were randomized to a n exercise group (n=12) or a control group (n=13). Patients in the exe rcise group resided in a rehabilitation center for 2 months and underw ent a training program consisting of two 1-hour sessions of walking da ily, along with four monitored 45-minute sessions of stationary cyclin g weekly. Before and after the study period, maximal exercise testing and cardiac MRI were performed. Oxygen uptake increased 26% at maximal exercise (19.7+/-3 to 23.9+/-5, P<.05) and 39% at the lactate thresho ld (P<.01) in the exercise group, whereas control values did not chang e. No differences were observed within or between groups in MRI measur es of end-diastolic (187+/-47 pre versus 196+/-35 mt post in the exerc ise group and 179+/-52 pre versus 180+/-51 mt post in the control grou p), end-systolic volume (118+/-41 pre versus 121+/-33 mt post in the e xercise group and 119+/-54 pre versus 116+/-56 mt post in the control group), Or ejection fraction (38.0+/-9 pre versus 38.2+/-10% post in t he exercise group and 37.0+/-10 pre versus 38.3+/-13% post in the cont rol group). Myocardial wall thickness measurements at end diastole and end systole and their difference in 80 myocardial segments determined by MRI yielded no significant interactions between groups. When myoca rdial wall thickness measurements were classified by infarct or noninf arct areas, no differences were observed between groups over the study period. Conclusions A high-intensity, 2-month residential cardiac reh abilitation program resulted in substantial increases in exercise capa city among patients with reduced left ventricular function. In contras t to some recent reports, the training program had no deleterious effe cts on left ventricular volume, function, or wall thickness regardless of infarct area.