Changes in exercise coronary sinus blood flow with training in patients with angina pectoris

Abstract

This study evaluated the effects of six months of bicycle ergometer training on coronary sinus blood flow (CSBF) and left ventricular oxygen consumption (LVO2) in 10 patients with exertional angina pectoris and angiographically documented coronary artery disease. CSBF was determined by thermodilution before and after training, with the patient in the upright position under the following conditions: at rest, during exercise at an equivalent work load, during exercise at an equivalent heart rate and at symptom-limited exercise. Although resting heart rate was significantly (P < 0.05) lower after training (78 ± 9 vs 70 ± 5 beats/min), CSBF, LVO2 and the product (PRP) of mean brachial artery pressure multiplied by heart rate were unchanged. At an equivalent work load averaging 400 kg-m/min heart rate (120 ± 14 vs 103 ± 11 beats/min), CSBF (163 ± 36 vs 135 ± 21), and PRP x 10-3 (15.2 ± 2.7 vs 12.4 ± 2.6) were significantly lower after training. LVO2 tended to be lower (20.1 ± 5.2 vs 17.3 ± 3.6 ml/min) but the change was not significant (P < 0.10). After training, patients could perform an 18% greater work load for a similar heart rate averaging 114 beats/min. CSBF, LVO2 and PRP were not significantly different despite this increase in absolute work load. Symptom-limited exercise capacity increased by 43% with training. Maximal values for CSBF (200 ± 56 vs 214 ± 50 ml/min), LVO2 (25.2 ± 5.3 vs 27.0 ± 5.0 ml/min) and PRP x 10-3 (16.8 ± 3.6 vs 18.7 ± 3.2) were not significantly different after training. The post-training increase in exercise tolerance of patients with angina pectoris does not depend on an augmented myocardial oxygen delivery, but is related to a reduction in coronary flow requirements for a given absolute work load.