Combined Use of Stress Echocardiography and Cardiopulmonary Exercise Testing to Assess Exercise Intolerance after Acute Myocardial Infarction

Abstract

Background: Exercise capacity (EC) after acute myocardial infarction (AMI) influences prognosis, but the causes of its reduction are complex and not sufficiently studied. Methods: We prospectively enrolled consecutive patients who underwent percutaneous coronary intervention for their first AMI with left ventricular ejection fraction (LV EF) >40% at least 4 weeks after AMI. We performed combined stress echocardiography and cardiopulmonary exercise testing (CPET-SE) using a semi-supine cycle ergometer to determine predictors of EC (peak oxygen uptake [VO2]). Results: Among 81 patients (70% male, mean age 58 ± 11 years), 40% had AMI with ST-segment elevation, and 60% non ST-segment elevation, LV EF was 57 ± 7%; wall motion score index, 1.18 (IQR 1.06 - 1.31); peak VO2, 19.5 ± 5.4 mL/kg/min. Multivariate analysis revealed that parameters at peak exercise: heart rate (β = 0.17, p < 0.001), stroke volume (β = 0.09, p < 0.001), and arteriovenous oxygen difference (A-VO2Diff, β = 93.51, p < 0.001) were independently positively correlated with peak VO2, with A-VO2Diff being its strongest contributor. Conclusions: In patients treated for AMI with normal/mildly reduced LV EF, EC is associated with peak peripheral oxygen extraction as well as peak heart rate and peak stroke volume. CPET-SE is a useful tool to evaluate decreased fitness in this group.