Introduction:
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 without residual coronary stenosis and with left ventricular ejection fraction (LVEF) > 40% more than 4 weeks after the 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 [VO
2
]).
Results:
Among 81 patients (70% male, mean age 58 ± 11 years), 40% suffered AMI with ST-segment elevation (STEMI), and 60% non-STEMI, LVEF was 57 ± 7%; wall motion score index, 1.18 (IQR 1.06 - 1.31); peak VO
2
, 19.5 ± 5.4 mL/kg/min. Multivariate analysis (
Table
) 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 (β = 93.51, p < 0.001) were independently positively correlated with peak VO
2
, with arteriovenous oxygen difference being its strongest contributor. At rest, left ventricular systolic and diastolic function parameters and the extent of myocardial scarring (wall motion score index) did not predict EC (p > 0.05).
Conclusions:
In patients treated for AMI with normal/mildly reduced LVEF, 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.
Exercise left ventricular outflow tract obstruction as a cause of exercise intolerance: combined stress echocardiography and cardiopulmonary exercise testing
