Cryptogenic Stroke and Underlying Atrial Fibrillation
How often is atrial fibrillation (AF) detected with an implantable loop recorder (ILR) in patients with a cryptogenic stroke or transient ischemic attack (TIA)?
Four hundred forty-four patients (mean age 61.5 years) with a stroke or TIA of unknown cause within the prior 90 days and no history of AF were randomly assigned to receive an implantable loop recorder (ILR, n = 221 patients), or to a control group in which electrocardiographic monitoring was at the discretion of the investigator (n = 220). The primary endpoint was time to detection of AF at 6 months of follow-up.
By 6 months of follow-up, AF ≥30 seconds in duration had been detected in a significantly larger proportion of patients in the ILR group (8.9%) than in the control group (1.4%). The monitoring strategy in the control group consisted of a 24-hour Holter monitor in 17 patients and an event recorder in one patient. By 12 months of follow-up, the AF detection rate was 12.4% in the ILR group compared to 2% in the control group.
The authors concluded that compared to conventional follow-up, an ILR increases the AF detection rate by approximately sixfold in patients with a cryptogenic stroke/TIA.
In another multicenter randomized study in the same issue of the New England Journal of Medicine (Gladstone DJ, et al., N Engl J Med 2014;370:2467-77), the yield of AF with a 30-day event monitor was 16.1%. Comparisons between studies generally are of limited value, but the data suggest that the more expensive ILR may not be superior to 30-day event monitors for AF detection after cryptogenic stroke.
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