Functional capabilities following coronary bypass surgery.

Changes in myocardial oxygen supply were evaluated in 19 patients following coronary by-pass surgery (CBS) for angina pectoris (AP). A symptom limited maximal functional graded exercise test (GXT) was performed before and 2-19 (X 7.5) months following CBS. After surgery the patients were urged to resume full activity and were individually managed in a 10-week "at home" exercise program. Increases were demonstrated for predicted oxygen uptake and work load (p less than .002), and rate pressure product (p less than .02) following CBS, suggesting increased myocardial blood flow. Terminal heart rate showed no significant increase. Of 16 patients exhibiting ST segment depression ( greater than or equal to .1 mV) with AP during GXT before surgery, 10 cases experienced total relief of both of these signs after surgery. A correlation between the pre-operative number of occluded coronary arteries (greater than 50%) and the degree of exercise induced ST segment depression revealed no significant trend. Additionally, no significant relationship was found between post-operative GXT results and the number of by-pass grafts performed on each patient. This study supports the premise that the effectiveness of CBS, in improving functional capacity, can be objectively evaluated by a non-invasive functional GXT.