Endocrine Abstracts

Introduction: Hypothyroidism is characterized by a decrease in oxygen and substrate utilization by major organ systems of the body. Hence patients with angina have fewer symptoms if they become hypothyroid. Hypothyroidism also results in bradycardia and weakening of myocardial contraction. Cardiac preload is decreased, afterload is increased, and chronotropic and inotropic functions are reduced. The impairment of these measures leads to a reduction in cardiac output.

Case Report: A 69-year-old male presents after a syncope. The patient reported no history of angina, syncope or seizure disorder except recent onset fatigue and dyspnea on exertion. He also complained of recent hair loss, hoarse voice and scrotal swelling.

The patient had no thyromegaly but had non-pitting pedal edema. Initial results showed, TSH of 122.1 mcU/ml, free T4 of <0.02 ng/dl, total T3 of 22 ng/dl. Thyroglobulin and thyroid microsomal antibodies were positive. His mental status was intact and showed no features of myxedema coma. He was started on a lower dose of levothyroxine (LT4) to prevent an arrhythmia. Patient had a transthoracic ECHO that showed severe left ventricular systolic dysfunction with an ejection fraction (EF) of 25% and global hypokinesis. Left heart catheterization showed triple vessel disease without complete occlusion. However, from the left ventriculogram, the EF improved to 60% after 3 days of LT4. The free T4 increased to 0.2 ng/dl. Eventually the patient had a coronary artery bypass grafting (CABG) where intraoperatively, the EF remained stable at 50%.

Conclusion: Our case describes a patient who was profoundly hypothyroid, yet had no features of myxedema coma and showed dramatic improvement after initiating LT4. The improvement in cardiac contractility prior to the CABG demonstrates the relationship between hypothyroidism and left ventricular dysfunction, and its reversible nature with restoration of thyroid function. Simultaneously, appropriate LT4 dose initiation is important to prevent arrhythmias.