Persistent improvement after coronary bypass surgery: ergometric and angiographic correlations at 5 years.

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Abstract
One hundred patients with angina pectoris who fulfilled specific entry criteria were randomly assigned to either medical therapy or bypass surgery. These groups were subjected to annual exercise testing during a 5-year follow-up period. The degree of revascularization was assessed by graft and native vessel angiography at 3 weeks, 1 year and 5 years after the operation. The exercise tolerance of the medical group remained largely unchanged during the follow-up. Eighty-five to 95% of the patients were using beta-blocking compounds at the successive testing situations. The surgical group exhibited a sustained improvement in exercise tolerance: Total work increased by 39-66% (p less than 0.02-0.001) and maximal ergometric load by 23-35% (p less than 0.01-0.001), and maximal ST depression decreased by 39-61% (p less than 0.05-0.001). The use of beta-blocking compounds in the surgical group steadily increased, from 44% at 6 months after operation to 63% of patients at 5 years. Division of the surgical group into subsets of complete and incomplete revascularization revealed that the improvement was confined to complete revascularization. Thus, the improved exercise tolerance after bypass surgery was a result of successful reestablishment of effective coronary perfusion; despite graft attrition (15% in 5 years) and new lesions in the native arteries, this improvement persisted for 5 years with appropriate medical therapy.