Cryptogenic stroke: Is silent atrial fibrillation the culprit?

BACKGROUND Stroke without an identifiable cause is frightening to patients and their families and is frustrating for the caring physician. Approximately 30% of patients with cardiac implanted electronic devices have some evidence of atrial fibrillation (AF), and much of it is silent: asymptomatic, and previously unrecognized. OBJECTIVE The purpose of this review is to examine "silent AF" as a potential cause of cryptogenic stroke. METHODS/RESULTS We begin by reviewing most of the published literature on screening for AF with different monitoring technologies in the setting of cryptogenic stroke. We present the results of 2 recent large randomized trials, CRYSTAL AF and EMBRACE, which compare standard of care monitoring in cryptogenic stroke patients to invasive and noninvasive monitoring strategies, respectively. Finally, we review the relationship of silent AF to stroke in the cardiac implanted electronic device population. Patient selection, duration of monitoring, sensitivity and specificity of monitoring technology, patient compliance, and several other factors affect the yield of AF detection during monitoring. CONCLUSION Data suggest that silent AF is identified in approximately 30% of cryptogenic stroke patients and has important therapeutic implications. Oral anticoagulation likely should be prescribed when silent AF is detected.