Isolated Right Heart Failure and Tricuspid Regurgitation in a Patient with Untreated Hyperthyroidism: A Case Report

Introduction: Hyperthyroidism has been known to cause a variety of cardiovascular manifestations. Isolated right heart failure (RHF) occurs occasionally, is usually due to pulmonary hypertension or tricuspid valve abnormalities. In rare cases, hyperthyroidism could be the underlying disease. Case Presentation: A 72-year-old woman with suspected but untreated hyperthyroidism presented with progressive dyspnea and lower extremity swelling in the last ten days. Physical examination showed an irregular and high heart rate, increase in JVP, enlargement of the thyroid gland, systolic murmur, and clear lungs. The laboratory findings showed an elevated level of free T4 (2.51 ng/dL) and a low level of TSH (<0.003 uIU/mL). Electrocardiogram revealed atrial fibrillation with a rapid ventricular response. Echocardiography showed right atrial and right ventricular dilatation with moderate tricuspid regurgitation. Left ventricular size and systolic function were normal. Chest x-ray showed a cardiothoracic ratio of 53% with organized left pleural effusion. Symptoms resolved as her thyroid hormone levels normalized with adequate treatment. Discussion: The most common changes that result from hyperthyroidism to the cardiovascular system are increased cardiac preload, decreased peripheral vascular resistance, direct injury, increased heart rate and contractility, which together produce a hyper dynamic circulatory state that leads to increased blood volume and venous return resulting in the increased risk of RHF. Conclusion: Hyperthyroidism is a potentially reversible cause of heart failure and should be ruled out in every heart failure patient, especially in those with isolated right heart failure, tricuspid regurgitation, and pulmonary hypertension. These conditions can potentially be well managed with adequate treatment.