Exercise training without ventricular remodeling in patients with moderate to severe left ventricular dysfunction early after acute myocardial infarction

Background: The purpose of this study was to determine whether or not patients with moderate to severe left ventricular (LV) dysfunction benefit from exercise training starting early after acute myocardial infarction (AMI) without deteriorating LV remodeling. Methods: We investigated changes in exercise capacity and LV end-diastolic dimension (LVDd by two-dimensional echocardiography) before and after exercise training in 126 patients after AMI. Patients were divided into three groups according to LV ejection fraction (EF) at the beginning of exercise training: 74 patients with LVEFgreater than or equal to45% (Group H), 35 patients with 35%less than or equal toLVEF<45% (Group M), and 17 patients with LVEF<35% (Group Q. Exercise training was prescribed at a moderate intensity (50-60% of heart rate reserve or Karvonen's equation). Exercise capacity was assessed by peak work rate (WR) and peak oxygen uptake (VO2) by upright cardiopulmonary exercise test before and after 3 months of exercise training. LVDd was measured before and at 27 10 months of follow-up period. Results: At the baseline, Group L had a significantly lower LVEF (H 55+/-7 vs. M 40+/-3 vs. L 30+/-3%, P<0.05), significantly greater LVDd (49+/-6 vs. 52+/-7 vs. 56+/-6 mm, P<0.05), and a higher incidence of anterior infarction (P<0.01) compared with Groups H and M, whereas there were no difference in age, sex, coronary risk factors, the incidence of multivessel disease, prior myocardial infarction, peak WR or peak VO2 among the three groups. After 3 months of exercise training, exercise capacity increased significantly (all P<0.01) in all groups. The magnitudes of the increases in peak VO2 (%Deltapeak VO2: 18+/-20 vs. 15+/-19 vs. 18+/-17%, NS) and peak WR (%Deltapeak WR: 17+/-17 vs. 16+/-14 vs. 15+/-13%, NS) were similar among the three groups. In addition, there was no significant correlation between %Deltapeak VO2 and baseline LVEF. No increase in LVDd was observed in any group at follow-up (H 48+/-5 to 49+/-4 mm vs. M 53+/-8 to 52+/-8 mm vs. L 57+/-5 to 57+/-7 mm, NS in each group). Conclusion: Patients with moderate to severe LV dysfunction benefit from exercise training starting early after AMI without deteriorating LV remodeling, with a similar magnitude of improvement in exercise capacity to that in patients with mild LV dysfunction. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.