Patients with large myocardial infarction gain a greater improvement in exercise capacity after exercise training than those with small to medium infarction.
BACKGROUND
It remains unclear whether patients with large-size myocardial infarction (MI) achieve the same benefit from exercise training as do those with small- to medium-size MI.


OBJECTIVE
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) (> or = 5000 U/l peak CPK, 64 patients) and the group with less extensive infarction (Group 2) (< 5000 U/I, 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)/VCO2 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.
Sakuragi
Satoru
S
Division of Cardiology, Department of Medicine, National Cardiovascular Center, Suita, Osaka, Japan.
Takagi
Shuichi
S
Suzuki
Shoji
S
Sakamaki
Fumio
F
Takaki
Hiroshi
H
Aihara
Naohiko
N
Yasumura
Yoshio
Y
Goto
Yoichi
Y
D000222:Adaptation, Physiological / Q000502:physiology; D023921:Coronary Stenosis / Q000150:complications; D003402:Creatine Kinase / Q000097:blood; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000145:classification / Q000150:complications / Q000534:rehabilitation*; D010101:Oxygen Consumption / Q000502:physiology; D013318:Stroke Volume; D016896:Treatment Outcome
D003402:Creatine Kinase