Stress Electrocardiography in the Evaluation of Surgical Revascularization of the Heart

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Abstract
Electrocardiography was carried out during hypoxemia and graded exercise tests before and at intervals between 2 and 20 months after attempts to revascularize the heart by internal mammary artery implantation in 44 patients with angiographically documented coronary disease and angina pectoris. Eleven patients had single vessel disease; the right coronary was involved in seven of these patients. Thirteen patients had single vessel implants, employing the left internal mammary artery in 11 patients and a saphenous vein graft from the aorta in two. Thirty-one patients had double internal mammary artery implantation accompanied by gastroepiploic arterial implantation in four. Fifty per cent of the patients were symptomatically improved after surgery, the best results occurring in two patients with isolated anterior descending coronary disease. Of the 34 patients having postoperative coronary and mammary arteriography, 15% showed improvement which could be ascribed to mammary revascularization; 24% had limited myocardial revascularization and no symptomatic improvement; 29% had patent implants without development of collateral vessels, and the implanted vessels were occluded in 32%. Eleven of the 34 (32%) had fair or good symptomatic improvement in the absence of revascularization. The results of postoperative stress electrocardiography correlated closely with the findings on postoperative coronary and mammary angiography. The stress tests were persistently positive after operation in 83% of the patients having angiographically confirmed implant occlusion or nonrevascularization. The stress ECG response was reversed, becoming negative postoperatively, in five cases of angiographically proved significant revascularization. Thus, stress electrocardiography provided objective evidence of improvement in a small number of patients with limited coronary disease who developed good collateral circulation and correlated with the lack of revascularization in the majority even in those subjectively improved.