A Randomized Comparison ofExercise Training inPatients WithNormal vs ReducedVentricular Function

Background: Exercise training isrecommended aftermyocardial infarction (MI) or bypass surgery inorder toimprove exercise tolerance. Insome patients, thedecrement inexercise capacity secondary todeconditioning andtheleft ventricular stunning associated withMI or coronary artery bypass graft (CABG) spontaneously improves after theevent.However, the impact ofthestatusoftheleft ventricle on theseimprovements isunknown. Methods: Sixty-seven patients 1monthafter MI or CABG were randomized toatraining (n=34; age, 59±7years) or a control group(n=33; age, 55±6years). Forty-two patients hadan ejection fraction >50%(22 inthetraining groupand20inthecontrol group), and25patients hadan ejection fraction <40%(12 intheexercise group and13inthecontrol group). After stabilization forapproximately 1monthafter theevent, patients intheexercise groupunderwent 8weeksof twicedaily exercise ata residential rehabilitation center, while control patients received usual care.Initially andafter 8weeks, patients inbothgroups underwent maximal exercise testing with gasexchange andlactate analysis. Results: Exercise training increased peak oxygen consumption (Vo2) only inthereduced ejection fraction group(19.4±3.0 to23.9±4.8mL/kg/min; p<0.05); theexercise groupwithnormal ventricular function didnotchange significantly. Changes inVo2atthelactate threshold paralleled thoseofpeak Vo2forbothgroups. Conversely, control patients withnormal ventricular function increased peak Vo2spontaneously (20.8±3.9 to 24.8±3.5mL/kg/min; p<0.01), whereas control patients withreduced ventricular function didnotimprove peak Vo2. Conclusion: Thesedatasuggest thatpatients withdepressed left ventricular function strongly benefit fromrehabilitation, whereas mostpatients withpreserved left ventricular function following MI or CABG tendtoimprove spontaneously 1to3monthsafter theevent. (CHEST 1998; 113:1387-93)