To Screen or Not for AF: Is That the Question?

Seemant Chaturvedi, MD

Two studies suggest longer-duration monitoring for AF is needed after apparently cryptogenic stroke, but many questions remain.

Up to one third of ischemic strokes are of uncertain etiology or “cryptogenic,” meaning that there is no overt explanation such as severe carotid stenosis, intracranial stenosis, or documented atrial fibrillation (AF). For some of these patients, intermittent AF may be present and could explain the ischemic stroke. This issue has been addressed by two recent studies.

In the EMBRACE study, researchers randomized 572 patients aged 55 or older with cryptogenic stroke to either 30-day electrocardiogram (ECG) monitoring with a portable event monitor or to a standard 24-hour ECG recording. The primary outcome was newly detected AF lasting 30 seconds or more within 90 days of study entry. This endpoint was detected in 16.1% of the prolonged monitoring group, compared with 3.2% in the control group (P<0.001). By 90 days, significantly more patients in the prolonged monitoring group than in the control group were placed on anticoagulants (19% vs. 11%).

The CRYSTAL AF investigators randomized 441 patients aged 40 or older with cryptogenic stroke to receive an insertable cardiac monitor (ICM) or undergo conventional follow-up. AF lasting more than 30 seconds was detected in 8.9% of the ICM patients versus 1.4% of the control group by 6 months (the primary endpoint; P<0.001). At 12 months, the rates were 12.4% vs. 2.0% (P<0.001). The median time from randomization to the first detection of AF was 84 days with ICM and 53 days with conventional follow-up.

Citation(s):

Gladstone DJ et al. Atrial fibrillation in patients with cryptogenic stroke. N Engl J Med 2014 Jun 26; 370:2467.

Sanna T et al. Cryptogenic stroke and underlying atrial fibrillation. N Engl J Med 2014 Jun 26; 370:2478.