The most common cause of an intracardiac mass is a thrombus. The left atrial mass was resected and proven to be a thrombus and was the presumed source of emboli that caused this patient's stroke. The mass was initially discovered on echocardiography and confirmed on CT. The patient did undergo head CT and brain MRI at presentation (not shown) which confirmed an acute ischemic stroke, shown in the chronic stage on the head CT above.