I am currently working as a trainee physician at The Cairns hospital.
An Unusual Case Of Atrial Fibrillation Due To A Mediastinal Mass
A 77-year-old male, an ex- heavy smoker, background history of interstitial lung disease, stroke and hypertension presented with two-day history of worsening shortness of breath and chest pain. The ECG at presentation showed Right Bundle Branch Block and premature atrial ectopics, patient became hemodynamically unstable, repeat electrocardiogram showed new onset of Atrial fibrillation. Echocardiogram showed normal cardiac size and function. Thyroid function test was normal. The computed tomographic pulmonary angiogram showed an incidental finding of large subcarinal mass abutting the left atrium and no evidence of pulmonary embolism. The biopsy of the mass confirmed metastatic non-small cell carcinoma of the lung.
Mediastinal masses are rare potential causes of Atrial Fibrillation. Several case studies have illustrated the causal relationship between compression of the left atrium by extra cardiac structures and the development of atrial fibrillation. (1)
The consequences of such compression could be hemodynamic instability, decreased cardiac output, pulmonary congestion and hypoxia as seen in this patient. Adequate treatment of tachyarrhythmia due to an extracardiac mass would involve removal of this mass where possible or reduce the size of the mass via chemotherapy or radiotherapy to enable relieving the pressure from the heart. (1,2) The patient’s heart rate settled with digoxin loading and subsequently with beta blockers. He was referred to the oncologist for further management of the cancer.
This case report further strengthens the hypothesis of association between left atrial compression by an extra-cardiac mass and new onset atrial fibrillation.