RESUMO
Atrial fibrillation is the most common sustained cardiac arrhythmia. While there have been reports of atrial fibrillation caused by the compression of pulmonary veins, we have not found reports of atrial fibrillation caused by the compression of the pulmonary artery. This report highlights the possible pathophysiology and management of atrial fibrillation in a patient with small cell lung cancer. The patient was admitted for hyponatremia secondary to syndrome of inappropriate antidiuretic hormone (SIADH) but subsequently developed tachycardia which progressed to atrial flutter and atrial fibrillation. Antiarrhythmics were ineffective until the patient received his first palliative chemotherapy for his small cell lung cancer. Subsequently, rate control was achieved with sotalol, with eventual conversion back to sinus rhythm. Management of atrial fibrillation is complex and sometimes depends on the underlying etiology. Early chemotherapy, in addition to antiarrhythmic drugs, may be beneficial in the management of patients with small cell lung cancer and atrial fibrillation. The CHA2DS2-VASc score does not take active malignancy into account and anti-coagulation should be evaluated on a case-by-case basis in this patient population.