Exercise at ventilatory threshold aggravates left ventricular remodeling in patients with extensive anterior acute myocardial infarction

Background The effects of physical training on ventricular remodeling after extensive anterior acute myocardial infarction (AMI) have not yet been defined. This randomized controlled study examines whether exercise aggravates left ventricular (LV) remodeling in patients with extensive anterior AMI. Methods Forty-eight consecutive patients with a first extensive anterior AMI and an LV ejection fraction (EF) of <45% assessed with left ventriculography (LVG) within 3 days of onset were randomly allocated to a training group (n = 24) or a control group (n = 24). Exercise intensity was determined by the heart rate of each patient at ventilatory threshold (VT). Three weeks after onset, a second LVG was performed, followed by a supervised exercise program at VT for 12 weeks. The LVG was reassessed after the exercise program. We then calculated the global LV volume (end-diastolic volume index [EDVI], end-systolic volume index [ESVI]) and systolic expansion volume index (SEVI), a new parameter for measuring the infarction site expansion at the end-systolic phase. Results Both EDVI and ESVI significantly decreased in the control group from 1 to 4 months after onset (91.2 ± 26.1 to 83.3 ± 24.0 mL/m2, P <.05; 52.4 ± 22.5 to 45.7 ± 18.8mL/m2, P <.01, respectively), but not in the exercise group. The SEVI also significantly decreased in the control group from 1 to 4 months (33.1 ± 16.9 to 25.7 ± 13.9 mL/m2, P <.05), but not in the training group (34.2 ± 12.9 to 36.5 ± 15.5 mL/m2, P = not significant). Conclusion Exercise while healing in patients with extensive anterior AMI, even at the VT level, induces LV enlargement and thus might aggravate LV remodeling. Therefore, in these patients, clinicians should consider withholding exercise training for at least 8 weeks, versus the 3-week period used in this trial.