MYOCARDIAL INFARCTION AND CARDIAC ARREST IN A PATIENT WITH SEVERE UNDIAGNOSED HYPOTHYROIDISM DURING BRONCHOSCOPY

Abstract Thyroid hormones have integral role on cardiac homeostasis, and hypothyroidism may be associated with impaired myocardial contractility, altered endothelial function, and blunted response to catecholamines. We describe a patient with undiagnosed severe hypothyroidism who developed an acute myocardial infarction and cardiac arrest during sedation for bronchoscopy. He required a prolonged resuscitation, which included coronary catheterization and placement of intra-aortic balloon pump. The resuscitation was noteworthy for blunted physiologic responses to large doses of epinephrine, in particular persistent bradycardia without evidence of conduction abnormalities. On admission to the intensive care unit, he was hypothermic (31.4⁰C), bradycardic, and hypotensive. Laboratory investigations revealed profound hypothyroidism, and thyroid hormone replacement was initiated. Within hours of initiation of thyroid hormone replacement, the need for vasopressor support was reduced. He had a complete recovery and was discharged home neurologically intact. We believe that this favourable neurologic outcome could be attributed to efficient resuscitation, prompt coronary revascularization, but also profound hypothermia likely related to a hypothyroidism-associated hypometabolic state.