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

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.