Percutaneous transluminal coronary angioplasty in hypothyroidism. PURPOSE: To determine the risks of percutaneous transluminal coronary angioplasty (PTCA) in hypothyroid individuals. PATIENTS AND METHODS: In a retrospective cohort study, 13 patients with primary hypothyroidism were identified among 382 consecutive PTCA cases in 1987. Twenty-two euthyroid PTCA control subjects and 13 hypothyroid patients who underwent coronary artery bypass surgery (CAB) were identified for comparison. RESULTS: Hypothyroid and euthyroid PTCA patients had similar mean ages, numbers of prior and recent acute myocardial infarctions, diseased coronary arteries, coronary arteries dilated, and serum cholesterol levels. There were no significant differences in procedure-related mortality (0% versus 0%); coronary artery dissection (23% versus 23%); reocclusion (8% versus 5%); bradycardia (0% versus 0%); heart failure (0% versus 5%); hypotension (31% versus 27%); myocardial infarction (8% versus 0%); gastrointestinal dysfunction (0% versus 0%); neuropsychiatric disturbance (15% versus 9%); hyponatremia (23% versus 23%); hypothermia (0% versus 0%); or fever (15% versus 5%). Hematoma formation tended to be more frequent in the hypothyroid group (38% versus 18%, p = 0.18). Similar results were obtained when the subgroup of more severely hypothyroid patients (thyrotropin level more than 20 mU/L, n = 7) was examined. Compared to hypothyroid CAB patients, hypothyroid PTCA patients had less incidence of heart failure (0% versus 31%, p less than 0.025); neuropsychiatric disturbance (15% versus 54%, p less than 0.025); hyponatremia (23% versus 62%, p less than 0.05); gastrointestinal dysfunction (0% versus 23%, p less than 0.025); and fever (15% versus 62%, p less than 0.001). CONCLUSION: PTCA can be performed in hypothyroid patients without increased mortality or major morbidity, and when appropriate, may be preferred to bypass surgery for coronary revascularization in patients intolerant of full thyroid hormone replacement. 