Implantable Loop Recorder Does Not Significantly decrease Ischemic strokes in AF: JAMA
A new investigation revealed that Implantable Loop Recorder screening for Atrial Fibrillation (AF) did not significantly decrease ischemic or severe strokes as published in JAMA Neurology.
Stroke is a major cause of mortality and disability throughout the world. Screening trials for AF have failed to demonstrate a significant reduction in stroke risk. As the impact on stroke severity and the importance of prior strokes are unknown, researchers conducted a study to assess stroke characteristics in patients undergoing implantable loop recorder (ILR) screening for AF vs usual care and assess the importance of prior stroke. A post hoc analysis of the Atrial Fibrillation Detected by Continuous Electrocardiogram Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals (LOOP) randomized clinical trial was done.
Participants who were 70 years or older without known AF but diagnosed with 1 or more of the following like hypertension, diabetes, heart failure, or prior stroke were taken. Participants were recruited from four sites in Denmark between January 31, 2014, and May 17, 2016. The median (IQR) follow-up period was 65 (59-70) months. There were two arms of intervention which were ILR screening for AF and anticoagulation initiation if AF duration of 6 minutes or longer was detected (ILR group) vs usual care (control group). The main outcome of measurement was adjudicated stroke, classified according to the modified Rankin Scale (mRS) using a score of 3 or more as a cutoff for severe (disabling or lethal) stroke, and according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification for ischemic strokes.
Results:
A total of 6205 individuals were screened for inclusion, and 6004 were randomized and included in the analysis.
| Parameter | Control Group | ILR group | Comment |
| No. of participants | 4503 | 1501 | mean age was74.7 years and had 2375 male participants in control group. mean age was 74.7 years and had 792 male participants in ILR group. |
| Prior stroke | 794/4503 | 262/1501 | |
| AF diagnosed in | 550 | 477 | 1027 participants had AF and anticoagulation was initiated in 89% of these. |
| Stroke during study | 249 | 66 | 315 participants in total had a stroke. The median (IQR) mRS score was 2 (1-3) with no difference across the groups. |
| Ischemic stroke | 217 | 55 | 272 had ischemic stroke in total. |
| severe stroke | 100 | 23 | 123 had sever stroke in total. |
| Hazard Ratios | 0.76 | 0.69 |
Thus, the researchers concluded from the post hoc analysis that ILR screening for AF did not result in a significant decrease in ischemic or severe strokes compared with usual care. They also found from their exploratory subgroup analyses that in participants without prior stroke there was a possible reduction of these outcomes.
Further reading: 10.1001/jamaneurol.2022.3031
Diederichsen SZ, Frederiksen KS, Xing LY, et al. Severity and Etiology of Incident Stroke in Patients Screened for Atrial Fibrillation vs Usual Care and the Impact of Prior Stroke: A Post Hoc Analysis of the LOOP Randomized Clinical Trial. JAMA Neurol. Published online August 29, 2022.
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