RANDOMIZED TRIAL OF A HOSPITAL-BASED EXERCISE TRAINING-PROGRAM AFTER ACUTE MYOCARDIAL-INFARCTION - CARDIAC AUTONOMIC EFFECTS

Objectives. This study sought to determine whether a moderate intensit y supervised exercise training program, performed immediately after an uncomplicated acute myocardial infarction, improves recovery in cardi ac autonomic function compared with standard advice about activity at home, Background. Exercise training has beneficial effects on cardiac autonomic function and may improve prognosis after acute myocardial in farction. Methods. Thirty-nine male and 10 female patients, mean (+/-S E) age 57 +/- 1 years, with an uncomplicated acute myocardial infarcti on were randomized to either a 6-week moderate intensity supervised ho spital-based exercise training program (exercise group) or to an unsup ervised low intensity home walking program (control group). Outcome me asures included changes in baroreflex sensitivity (phenylephrine bolus method) and heart rate variability (24-h Holter monitoring) and the e ndurance time at 85% of peak oxygen consumption. Results. At baseline, there were no significant differences in left ventricular ejection fr action (57 +/- 2% vs. 53 +/- 2%), frequency of anterior infarction (27 % vs. 18%) and peak creatine kinase (1,256 +/- 170 vs. 1,599 +/- 295 I U) between the exercise and control groups. Baroreflex sensitivity (10 .5 +/- 1.0 vs. 8.4 +/- 1.2 ms/mm Hg) and time domain measures of heart rate variability were also similar. After completion of the program, the exercise group exercised for a median of 15 min (interquartile ran ge 12 to 25) at a workload of 104 +/- 7 W compared with 7 min (interqu artile range 3.5 to 12) at a workload of 89 +/- 8 W in the control gro up (p < 0.01). There were significant (p < 0.001) improvements in baro reflex sensitivity and heart rate variability for the 49 patients comb ined but no differences between the exercise and control groups. Baror eflex sensitivity improved by 3.4 +/- 1.0 and 1.7 +/- 1.0 ms/mm Hg and the standard deviation of 24-h RR intervals by 36 +/- 6 and 40 +/- 10 ms, respectively (p > 0.1), Conclusions. A hospital based exercise tr aining program increased endurance capacity but did not improve recove ry of cardiovascular autonomic function after uncomplicated acute myoc ardial infarction. (C) 1997 by the American College of Cardiology.