Abstract
Background
The benefit of exercise on peripheral muscles is established but the exact role of the coronary microcirculation in exercise capacity after cardiac rehabilitation (CR) is unclear. Objective: Our aim was to test the relationship between non-invasive coronary flow reserve (CFR) and exercise capacity in patients undergoing CR after acute myocardial infarction (AMI).
Methods
CFR was performed by transthoracic Doppler echocardiography in the left anterior descending artery 24 h after angioplasty (CFR1) and after 20 sessions of CR program (at 4±1 months) (CFR2) in 60 consecutive patients (57±11 years, 30% women) with an anterior AMI successfully treated by primary coronary angioplasty. CFR was performed in a modified parasternal view using intravenous adenosine infusion (0.14 mg/kg/min within 2 minutes). CR program consisted of a half hour of fractioned exercise added of a half hour session of general gymnastics and body building. To test the exercise capacity, symptom limited exercise echocardiography was performed just after the CFR2, in a semi-supine position, starting at 25 watts, with 20–25 watts increments of workload every two minutes.
Results
CFR was measured successfully in all patients, and CFR2 was significantly higher than CFR1 (2.9±0.65 vs 1.9±0.4, p<0.001). Though CFR1 was correlated to left ventricular systolic function and its improvement at follow-up (all, p<0.01), CFR2 was independently related to exercise capacity (mean workload 100±30 watts, percent maximal heart rate 83±12%, no ischemia, no new wall motion abnormalities in all tests) after adjusting for age, sex, and body mass index (r=0.6, p<0.01).
Conclusion
CFR predicts exercise capacity in patients undergoing a CR program after AMI. The improvement of CFR contributes to cardiac performance.
Coronary flow reserve as a link between diastolic and systolic function and exercise capacity in heart failure
