Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia characterized by irregular, disorganized and rapid atrial activation leading to an irregular ventricular contraction. Almost any cardiovascular condition can cause AF, common being hypertension, coronary artery disease, heart failure, valvular heart disease (including rheumatic), cardiomyopathy, pericarditis, congenital heart disease etc. Extra-cardiac causes include thyrotoxicosis, chest trauma, thoracic or cardiac surgery, obstructive sleep apnea, pulmonary disease, pulmonary embolism, medication use (e.g. theophylline, beta agonist etc.), alcohol excess and withdrawal etc. In this paper, we report a case of LA compression from an extra-cardiac mass and new onset AF, wherein the AF resolved after chemotherapy. In addition, we include a review of the literature of similar cases and discuss the possible association between LA compression and new onset AF.