Newer anticoagulants can be used off-label.

hat is the diagnosis? Stroke neurologists make use of inductive reasoning, a probabilistic exercise, to determine stroke mechanism. Where ≥1 possible mechanism exists, we typically adopt the philosophy of Occam's razor, assuming that 1 mechanism is dominant. The ensuing approach to preventive treatment rationally follows the determination of stroke mechanism. The appearance of an embolic-looking stroke on brain imaging usually implies a wedge-shaped cor-tical infarct or multiple scattered infarcts in one or multiple arterial territories. Embolic stroke may be of arterial, cardiac or less commonly, venous origin (paradoxical embolism). From the case history, we infer that arteroembolic stroke arising from a ruptured atherosclerotic plaque is less likely given the unrevealing computed tomographic angiogram. We have no immediate evidence of atrial fibrillation (AF), and we assume that the echocardiographic assessment done to determine the low ejection fraction does not show any alternate source of cardioembolism. The low ejection fraction suggests a cardioembolic source, but what kind? Results from a recent randomized controlled trial support the use of prolonged cardiac monitoring in patients after transient ischemic attack or embolic stroke after negative standard vascular and cardiac investigations. Assuming that there is no evidence of AF, then the working diagnosis of stroke mechanism becomes a small, unseen, intracardiac mural thrombus formed because of poor cardiac function that embolized to the intracranial circulation causing a stroke. An additional careful look at the heart with transesophageal echocardiography may be considered, but the yield is likely to be low. Newer techniques , such as cardiac computed tomography or MR, may yet yield further insights into nonvalvular, non–AF-specific causes of cardioembolic stroke, but their use has yet to be proven. The prevention of subsequent stroke in this scenario was examined in a large, double-blind randomized controlled trial, Warfarin and Aspirin in Patients With Heart Failure and Sinus Rhythm (WARCEF) which tested whether warfarin or aspirin was superior for stroke or systemic embolism prevention among subjects with low ejection fraction but in sinus rhythm. There was no significant overall difference in the primary composite end point of stroke and all-cause mortality between the 2 treatment groups.