Extended monitoring effective at detecting silent atrial fibrillation after cryptogenic stroke

1. In post-embolic “cryptogenic” stroke patients, the use of a 30-day event-triggered cardiac recorder was superior at detecting atrial fibrillation compared to an extra round of a 24-hour Holter monitor. 

Evidence Rating Level: 1 (Excellent)       

Study Rundown: An estimated 1 in 4 ischemic strokes are labeled “cryptogenic”, whereby standard post-stroke investigations does not yield a clear etiology. Atrial fibrillation is an arrhythmia that is often both intermittent (e.g., paroxysmal) and asymptomatic. Therefore it is also thought to be the cause for many of these cryptogenic strokes. However, secondary prevention with anticoagulation (in post-stroke patients) is typically not indicated unless there is documentation of atrial fibrillation. Thus, various modalities to improve the detection of atrial fibrillation are currently under investigation.

This open-label, multi-center trial randomized post-ischemic “cryptogenic” stroke patients (with no history of atrial fibrillation, within 6 months of the event) to either cardiac monitoring with a 30-day event-triggered loop recorder versus an extra round of a 24-hour Holter monitor. The primary endpoint of detecting atrial fibrillation (lasting >30 seconds) within 90-days was significantly improved with the loop recorder.

Event-triggered recorders required that patients be compliant with attaching the device on each day for 30-days while the Holter monitor typically remains attached to the patient for the entire period of the study, thus compliance may have limited the results of this study. Variation in the immediate post-stroke investigations may have varied among all patients enrolled (as there were several centers involved each with different resources), therefore other etiologies for embolic stroke aside from atrial fibrillation may have contributed.

This study showed the importance of extending the duration of cardiac monitoring in order to increase the detection of atrial fibrillation in post-stroke patients. Future studies will likely focus on comparing the detection of atrial fibrillation using current and newer outpatient devices as well as determining a feasible yet optimal duration for improving detection.

Click to read the study, published today in NEJM

Click to read an accompanying editorial in NEJM

In-Depth [randomized controlled trial]: This study randomized 572 post-ischemic “cryptogenic” stroke patients within 6 months to either a 30-day loop recorder (intervention) or a second 24-hour Holter monitor (control) for detection of atrial fibrillation. The primary endpoint of detecting atrial fibrillation within 90-days of randomization occurred in 16.1% and 3.2% (p<0.001) in loop recorder and Holter groups, respectively. The higher rates of detecting atrial fibrillation also changed management as more patients in the intervention group received anticoagulation (18.6% vs. 11.1%, intervention vs. control, p=0.01) or were switched from antiplatelet therapy to anticoagulation (13.6% vs. 4.7%, intervention vs. control, p<0.001).

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Image: PD 

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