Case History: 41-year-old female presented with a 3-day history of fever, cough, and breathlessness. She had palpitations, diarrhoea and weight loss of 4-5 kg over 1 month. Graves disease had been diagnosed 5 years prior to this episode and she had been treated with carbimazole but was not in remission. On this occasion, she was febrile and had atrial fibrillation. She also had right pleural effusion and bilateral pedal oedema.
Investigations: Blood tests confirmed Graves thyrotoxicosis (T4 100pmol/l, T3 40.2pmol/l, TSH <0.03mU/l and high TSH receptor antibody 17U/l). She had high BNP 1141ng/l and deranged liver function tests. Chest X-ray and a CT chest confirmed a large right-sided pleural effusion causing near complete collapse of the right lung. Echocardiography showed an enlarged right ventricle (RV) with severe tricuspid regurgitation and raised pulmonary artery pressure (PAP 43-48mmHg).
Treatment: Diagnosis of Graves thyrotoxicosis with impending thyroid storm was made. She was treated on ITU with carbimazole 60mg, prednisolone 40mg a day and beta-blockers. A chest drain was inserted to reduce the right-sided effusion. She had radioactive iodine 500MBq but was still requiring carbimazole 20mg to control thyroid function 7 months later (T4 18.9pmol/l, T3 5.8pmol/l, TSH <0.02mU/l). Repeat echocardiography showed resolution of pulmonary hypertension (PAP 20-25mmHg) and normal RV.
Discussion: Left ventricular failure is known to be associated with thyrotoxicosis, whereas RV dysfunction and pulmonary hypertension are not well-recognised complications. Several case reports describe an association between thyrotoxicosis and RV failure mostly seen in female patients with newly diagnosed Graves disease. Signs of RV failure and pulmonary hypertension resolve when euthyroidism is achieved. RV dysfunction is predominantly driven by increased cardiac output and pulmonary vascular resistance. The condition may be under-diagnosed due to the non-specific symptoms of breathlessness and fatigue. Signs and symptoms of RV dysfunction should be sought in all patients with newly diagnosed thyrotoxicosis. In patients with unexplained RV failure or pulmonary hypertension thyroid dysfunction should be checked as it may improve with restoration of euthyroidism.