Patients with large myocardial infarction gain a greater improvement in exercise capacity after exercise training than those with small to medium infarction
It remains unclear whether patients with largesize myocardial infarction (MI) achieve the same benefit from exercise training as do those with small-to medium-size MI. Hypothesis: This study was designed to determine the magnitude and mechanisms underlying improvement in exercise capacity in patients with large-size MI after cardiac rehabilitation. Methods: In all, 296 patients who participated in a cardiac rehabilitation program after acute MI were divided into two groups according to the peak
... serum creatine phosphokinase (CPK) level: the group with large infarction (Group 1) (≥ 5000 U/l peak CPK, 64 patients) and the group with less extensive infarction (Group 2) (< 5000 U/l, 232 patients). Exercise capacity was assessed before and after a 3-month cardiac rehabilitation program that included exercise training. Results: Before exercise training, both the peak work rate (p < 0.05) and peak oxygen uptake (VO2) (p < 0.01) were significantly lower in Group 1 than in Group 2. After exercise training, the changes in peak work rate and peak VO2 were significantly greater in Group 1 than in Group 2 (both p < 0.01). The infarction size measured by the peak CPK level correlated significantly with both the baseline exercise capacity and its improvement after exercise training, although these correlations were insignificant in a multivariate analysis. In the multivariate analysis, the improvement in exercise capacity is determined by age and baseline exercise capacity, which is determined by the duration of inactivity, minute ventilation (VE)/ VCO 2 slope and left ventricular end-diastolic pressure. Conclusions: Compared with patients with small-to medium-size myocardial infarction, patients with large infarction gain a greater improvement in exercise capacity after exercise training due to reversal of physical deconditioning and improvement in congestive heart failure.