Restoration of sinus rhythm following levothyroxine treatment in a case of primary hypothyroidism presenting with atrial fibrillation and pericardial effusion
A 72-year-old male presented with palpitations, dyspnea, and chest discomfort. He had episodes of “fast heart beats” for 3 months. He complained of chest pain which was substernal, nonradiating, and throbbing in nature. He had no other positive history suggestive of any other disorder. He smoked 10 cigarettes per day for past 25 years, and denied use of alcohol, caffeine, or drugs. Physical examination was unremarkable except for the irregular heart rate (approximately 130 beats per min) and muffled heart sounds on auscultation. Electrocardiogram [] confirmed AF with rapid ventricular rate, which responded to initial treatment with metoprolol [].\nThyroid function tests revealed a sensitive thyroid stimulating hormone (TSH) concentration of 34.70 μIU/ml (normal: 0.40-4.70 μIU/ml), and thyroxine (T4) of 5.57 μg/dl (normal: 8-12 μg/dl) confirming primary hypothyroidism.\nAnti-thyroperoxidase antibodies were negative. His blood counts, serum electrolytes, and serial cardiac enzymes were normal. Chest X-ray revealed mild cardiomegaly. Transthoracic echocardiography showed normal left ventricular systolic function (ejection fraction of 63%), decreased left ventricular diastolic compliance, and massive pericardial effusion (posterior 17 mm, anterior 13 mm). Right atrial and right ventricle showed 30% collapse during diastole, mild left ventricular hypertrophy was present with no regional wall motion abnormalities.\nPatient was treated with levothyroxine which lead to resolution of symptoms and restoration of normal sinus rhythm. Repeat echocardiography showed no collapse of right atrium and right ventricle during diastole) and mild pericardial effusion (11 mm circumferential).