Mechanisms of Exercise Capacity Improvement after Cardiac Rehabilitation Following Myocardial Infarction Assessed with Combined Stress Echocardiography and Cardiopulmonary Exercise Testing.

Krzysztof Smarz,Maciej Tysarowski,Andrzej Budaj,Beata Zaborska,Tomasz Jaxa-Chamiec

doi:10.3390/jcm10184083

Abstract

Cardiac rehabilitation (CR) is indicated in all patients after acute myocardial infarction (AMI) to improve prognosis and exercise capacity (EC). Previous studies reported that up to a third of patients did not improve their EC after CR (non-responders). Our aim was to assess the cardiac and peripheral mechanisms of EC improvement after CR using combined exercise echocardiography and cardiopulmonary exercise testing (CPET-SE). The responders included patients with an improved EC assessed as a rise in peak oxygen uptake (VO2) ≥ 1 mL/kg/min. Peripheral oxygen extraction was calculated as arteriovenous oxygen difference (A-VO2Diff). Out of 41 patients (67% male, mean age 57.5 ± 10 years) after AMI with left ventricular ejection fraction (LVEF) ≥ 40%, 73% improved their EC. In responders, peak VO2 improved by 27% from 17.9 ± 5.2 mL/kg/min to 22.7 ± 5.1 mL/kg/min, p < 0.001, while non-responders had a non-significant 5% decrease in peak VO2. In the responder group, the peak exercise heart rate, early diastolic myocardial velocity at peak exercise, LVEF at rest and at peak exercise, and A-VO2Diff at peak exercise increased, the minute ventilation to carbon dioxide production slope decreased, but the stroke volume and cardiac index were unchanged after CR. Non-responders had no changes in assessed parameters. EC improvement after CR of patients with preserved LVEF after AMI is associated with an increased heart rate response and better peripheral oxygen extraction during exercise.

Highlights

Patients after acute myocardial infarction (AMI) entering cardiac rehabilitation (CR)often have a low exercise capacity (EC) and it is well established that a low EC is strongly associated with a poor prognosis [1,2,3,4]
In patients with AMI treated with percutaneous coronary intervention, CR based on aerobic exercise and strength training is safe and improves functional capacity, as well as the test duration, workload, and heart rate response [7,8,9]
Out of 61 patients treated for AMI and referred for CR who had performed cardiopulmonary exercise testing and stress echocardiography (CPET-SE)

Summary

Introduction

Patients after acute myocardial infarction (AMI) entering cardiac rehabilitation (CR)often have a low exercise capacity (EC) and it is well established that a low EC is strongly associated with a poor prognosis [1,2,3,4]. Patients after acute myocardial infarction (AMI) entering cardiac rehabilitation (CR). In The Henry Ford Exercise Testing (FIT) Project, in patients with known coronary artery disease, EC was a strong predictor of mortality, myocardial infarction, and downstream revascularizations. Patients with similar EC had an equivalent mortality risk, irrespective of the baseline revascularization status [5]. In patients with AMI treated with percutaneous coronary intervention, CR based on aerobic exercise and strength training is safe and improves functional capacity, as well as the test duration, workload, and heart rate response [7,8,9]. In a large and representative community cohort of Dutch patients with the acute coronary syndrome, CR was associated with a survival benefit regardless of age, type of diagnosis, and type of intervention [10]

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