CASE PRESENTATION: A 65-year-old non-smoking female professor presented with worsening cough, shortness of breath, mild hypoxemia, and inability to lecture two weeks after RFA for atrial fibrillation. Chest x-ray showed a new left lower lobe infiltrate and pleural effusion (Fig-1). PaO2 was 64mmHg on room air. Echocardiogram demonstrated preserved left ventricular ejection fraction, normal valvular function, and a small pericardial effusion with thickened pericardium. A cardiac CT scan revealed complete thrombosis of the left inferior pulmonary vein with evidence of evolving pulmonary infarction in the left lower lobe (Fig-2). Cumulative stenosis score (CSI) was calculated as 50%. Surprisingly, a ventilation-perfusion scan (V/Q) was unremarkable, with only mild retention of activity in the left lower lung suggestive of obstructive physiology. Although the patient was severely symptomatic and her CT scans showed early pulmonary infarction, endovascular intervention (thrombolysis, angioplasty/stenting) was considered high-risk. Given the absence of severe impairment on V/Q scan, CSI score less than 75%, and the fact that her symptoms could be partially due to pericarditis, the decision was made to treat conservatively with anticoagulation and close monitoring. Six months later, she is now asymptomatic, and weaned off all antiarrhythmic and anticoagulant medications.