Cardiac function and maximal exercise capacity early after acute myocardial infarction

The purpose of the study was to assess the relationship betweenleft and right ventricular function measured at rest and maximalexercise capacity in patients with recent acute myocardial infarction(AMI). Forty-three male patients (Killip Class I, n=36; KillipClass II, n=7) with a wide range of left ventricular (LV) functionand size underwent graded bicycle exercise testing less than4 weeks after AMI (mean 21 days, 17–27). None of the patientshad exercise limiting factors other than dyspnoea and fatigue.Left and right ventricular ejection fractions were determinedby a radionuclide ventriculo graphic method which also alloweddetermination of absolute LV volumes and actual LV peak fillingrate. LV ejection fraction had a tt weak association to estimatedmaximal oxygen uptake (VO₂ max) (r=0·37). No associationwas found between LV size, LV stroke volume, or LV peak fillingrate and estimated VO₂ max. Similarly, right ventricular ejectionfraction showed no correlation to estimated VO₂ max. Patientswith well preserved LV function had a higher exercise inducedincrease in systolic blood pressure than patients with reducedLV function, but the increase in systolic blood pressure couldnot be used to estimate LV function with any reasonable accuracy. We conclude that the maximal exercise capacity of patients withrecent AMI is virtually independent of their left and rightventricular function determined at rest, and that exercise testingand radionuclide ventriculography should be regarded as complementaryprocedures in the evaluation of patients with AMI.