Detection of occult atrial fibrillation by pacemaker interrogation in cryptogenic stroke

Atrial fibrillation (AF) is a major cause of ischemic strokes, and it is assumed that occult intermittent episodes of AF are responsible for some of the seemingly cryptogenic strokes. Cardiac pacemakers feature rhythm diagnostic capabilities and data storage. We investigated whether pacemaker memory interrogation led to identification of undetected AF episodes prior to cryptogenic strokes.

The study enrolled all patients admitted between June 2010 and July 2013 for an acute cryptogenic stroke and who were implanted with a permanent pacemaker. Patients with a history of AF and a history of stroke with an identifiable origin were excluded. Pacemaker memories were interrogated to determine the presence of AF prior to the stroke and its temporal relationship with the stroke.

Fourteen patients (nine men and five women) with a median (interquartile range) age of 84.5 (82.25-87.5) years were included. Median CHADS2 and CHA2DS2-VASc scores were 2 (1-2.75) and 3.5 (3-4), respectively. Pacemaker memories were activated in 13 patients with atrial arrhythmia detection based on an atrial cutoff rate in 8 patients and on the detection of atrial rate acceleration in 5 patients. Electrograms were available for review in 10 patients. Unknown AF or atrial flutter was diagnosed previous to the stroke in six (43 %) patients. Four patients experienced more than one arrhythmia episode. The last episode occurred in the 48 h prior to stroke in three patients and in the previous 4 weeks in five patients. Anticoagulation was started after the stroke in all of these six patients.

Pacemaker interrogation has a high diagnostic yield in seemingly cryptogenic stroke, with frequent detection of occult AF. The causal link between AF and stroke is convincingly reinforced by their close temporal proximity, and anticoagulation is warranted in this clinical situation.