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Screening high-risk patients for atrial fibrillation with implantable loop recorder does not prevent stroke or systemic emboli (LOOP)
Clinical Question
Does screening high-risk adults for atrial fibrillation using an implantable loop recorder prevent stroke?
Bottom line
In this large study, using ILR rather than usual care to screen for atrial fibrillation resulted in the detection of 3 times more atrial fibrillation, but did not reduce the risk of stroke or systemic arterial embolism—the real reason we worry about atrial fibrillation. 1b-
Reference
Study design: Randomized controlled trial (nonblinded)
Funding: Foundation
Setting: Outpatient (specialty)
Synopsis
This study took place in 4 centers in Denmark. The authors enrolled persons without atrial fibrillation who were aged 70 years to 90 years and had at least one additional risk factor for stroke (eg, hypertension, diabetes, previous stroke, or heart failure). They randomized the participants in a 1:3 ratio to receive an implantable loop recorder (ILR; n = 1501) or an annual interview with a study nurse, standard contact with the participant’s general physician, and an electrocardiogram as needed (n = 4503). Those in the ILR group were continuously and remotely monitored, and if the monitoring site detected atrial fibrillation lasting at least 6 minutes, they contacted the participant and recommended anticoagulation (the type of anticoagulation was left to the treating clinician and patient). The data-monitoring committee ended the study early because the prespecified number of events had occurred. In the ILR group, the median monitoring duration was 39.3 months. For both groups, the median follow-up was 64.5 months. The authors report having lost 0 patients to follow-up. Atrial fibrillation was detected in 477 (31.8%) patients in the ILR group compared with 550 (12.2%) in the control group. The treating clinicians initiated oral anticoagulation in 445 (29.7%) participants in the ILR group compared with 591 (13.1%) in the control group. The authors report no significant difference in the primary outcome of stroke or systemic arterial embolism (analyzed via intention to treat). This primary outcome occurred in 67 (4.5%) patients in the ILR group compared with 251 (5.6%) in the control group. The rate of major bleeding was also comparable between the groups (4.3% vs 3.5%, respectively).
Reviewer
Henry C. Barry, MD, MS
Professor
Michigan State University
East Lansing, MI
Comments
Screening
"The harder you look, the more you find". This study is yet another example.
Screening for A-fib
Interesting article with lots of food for thought as to why why there were no differences. In a way reassuring that for now there is no compelling reason that mandates we "go out and search" for new onset of A-fib (well at least 6 min of A-fib) in this population.
ILR detects more a fib but no difference in stroke rate comp
Surprising result - very counterintuitive.
loop recorder use in a fib
no decrease in events even though a fib found sooner