Hypothyroidism and Atherosclerotic Heart Disease: Pathogenesis, Medical Management, and the Role of Coronary Artery Bypass Surgery

OVERT HYPOTHYROIDISM is associated with a number of abnormalities in lipid metabolism which may predispose patients to accelerated coronary artery disease. Despite a high prevalence of severe atherosclerosis found at autopsy, hypothyroid patients have a relatively low frequency of angina pectoris and myocardial infarction during life. Problems typically arise during thyroid hormone replacement therapy when the new onset of angina, unstable angina, myocardial infarction, or sudden death may occur, making treatment of the hypothyroidism difficult and potentially dangerous. For many years the possible hazards of anesthesia and surgery in hypothyroid patients discouraged the use of coronary revascularization as a treatment for their angina pectoris. Many patients had to remain hypothyroid in order to avoid exacerbation of their cardiac symptoms. Since 1974 however, 49 hypothyroid patients with chest pain and an inability to tolerate thyroid hormone have been successfully treated with coronary revascularization after failing standard antianginal medical therapy. The clinical outcomes of these patients are reviewed. It appears from the literature that cardiac catheterization and coronary artery bypass surgery can be carried out safely and with excellent long term results in hypothyroid patients with or without prior thyroid hormone administration. Overt Hypothyroidism is associated with a number of abnormalities in lipid metabolism which may predispose patients to accelerated coronary artery disease. Despite a high prevalence of severe atherosclerosis found at autopsy, hypothyroid patients have a relatively low frequency of angina pectoris and myocardial infarction during life. Problems typically arise during thyroid hormone replacement therapy when the new onset of angina, unstable angina, myocardial infarction, or sudden death may occur, making treatment of the hypothyroidism difficult and potentially dangerous. For many years the possible hazards of anesthesia and surgery in hypothyroid patients discouraged the use of coronary revascularization as a treatment for their angina pectoris. Many patients had to remain hypothyroid in order to avoid exacerbation of their cardiac symptoms. Since 1974 however, 49 hypothyroid patients with chest pain and an inability to tolerate thyroid hormone have been successfully treated with coronary revascularization after failing standard antianginal medical therapy. The clinical outcomes of these patients are reviewed. It appears from the literature that cardiac catheterization and coronary artery bypass surgery can be carried out safely and with excellent long term results in hypothyroid patients with or without prior thyroid hormone administration. The treatment of myxedema in the setting of coronary atherosclerosis is a potentially difficult and frustrating experience for both the practicing clinician and the patient (1). Over the past 20 years however, the management of patients with coexisting hypothyroidism and coronary artery disease has undergone some major revisions. Particularly in the last decade, the surgical treatment of coronary atherosclerosis in patients with clinical hypothyroidism has assumed a new and important role. This article will review the progress of the past 10 years in the management of these two disorders focusing on the role of coronary artery bypass surgery in hypothyroid patients with angina. Also to be examined will be the evidence linking hypothyroidism to ischemic heart disease and the inherent difficulties involved in the medical management of concomitant hypothyroidism and coronary artery disease.