Endocrine Abstracts

Introduction

Graves’ disease is an autoimmune disorder that has multiple cardiac repercussions including arrhythmias and heart failure. Acute myocarditis is a rarely described complication. In this context, we report a case illustrating this association.

Case presentation

A 23-year-old man has been followed for Graves’ disease that had been suspected by weight loss, tachycardia and bilateral and asymetric proptosis. The diagnosis had been confirmed with an fT4 at 27 pmol/l (1.42 times the normal), TSH at 0.04 IU/l (n:0.35-4), anti-TSH receptor antibodies positive at 40 IU/l and on thyroid ultrasound a hypervascular and enlarged thyroid gland. The patient was treated with carbimazole 30 mg per day and propranolol 60 mg per day. One year later, he was seen for oppressive chest pain, with an ECG showing an inferolateral elevated ST segment and an anteroseptal ST segment depression. The troponin level was 21.627 ng/l. Acute coronary syndrome has been suspected. The patient was put on dual antiaggregant and anticoagulation. He had a coronarography showing normal coronary arteries. Transthoracic ultrasound showed hypokinesia of the mid and basal segments of the anterolateral and inferior walls with an ejection fraction at 50%. A myocardial magnetic resonance imaging was then practiced and showed an aspect of myocarditis. Since the patient was apyretic, did not present arthromyalgia and there was no biological inflammatory syndrome, the viral origin was eliminated. The diagnosis of autoimmune myocarditis was then retained. Therapeutically, he was kept on a beta blocker and received radioiodine therapy twice. The evolution was marked by post radioiodine hypothyroidism which was then substituted with l-thyroxin and by the absence of recurrence of chest pain.

Conclusion

Acute myocarditis is an unusual affection in Graves’ disease. The mechanism is different from of the cardiothyreosis which is linked to a direct effect of thyroid hormones on the heart. An autoimmune mechanism has been implicated in this entity which can be confirmed histologically by the presence of anti TSH receptor antibodies in cardiomyocytes. Hence the importance of careful cardiac exploration in Graves’ disease.