#VisualAbstract: Screening patients with atrial fibrillation with an implantable loop recorder does not reduce the incidence of subsequent stroke

1. Among patients 70 years of age or older, screening for atrial fibrillation using an implantable loop recorder did not prevent ischemic or severe stroke compared to the control group.

2. Subgroup analysis revealed that implantable loop recorders may reduce the incidence of stroke in patients who have not previously had a stroke.

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Study rundown: Atrial fibrillation is an important risk factor for stroke that is often underdiagnosed or poorly controlled. Extended cardiac monitoring with a device such as an implantable loop recorder (ILR) can improve the ability to detect whether a patient has atrial fibrillation. In theory, this may also indicate times when the risk of developing an embolic event (ie stroke or TIA) is increased. The current randomized controlled trial sought to determine whether ILR could prevent stroke in patients 70 years of age or older who had at least one other risk factor for stroke.

6004 patients were followed in this study, including 4503 in the usual care (control) group and 1501 in the ILR group. Baseline characteristics were balanced between the two groups. 1027 patients were diagnosed with atrial fibrillation during the study period including 550 (12%) in the ILR group and 477 (32%) in the control group. 5.2% of patients in the study had a stroke during the study period including 5.5% of patients in the control group and 4.4% of patients in the ILR group. The overall rate of stroke was not significantly different between patients in the control group and the ILR groups. 2.0% of patients had a severe stroke according to the standard classification; This was not significantly different between the control and experimental groups.

This randomized controlled trial showed that there was no overall difference in the stroke rate between patients aged 70 years or older at risk of stroke whether or not they had an ILR in place. Although there may be some benefit in patients who have no previous history of stroke. Additional research should develop effective interventions for this group of patients when they are identified as being at high risk of stroke to improve outcomes. The strength of this work includes the well-functioning stochastic design to control for confounding variables. However, this study is limited as the data were analyzed retrospectively, being a post hoc analysis.

Click here to read this study in JAMA Neurology

Related reading: Atrial fibrillation and stroke mechanisms: time for a new paradigm

in depth [randomized controlled trial]: This article refers to the post-analysis of the LOOP trial conducted in several centers in Denmark as a randomized controlled trial. Individuals aged 70 or older who had no history of atrial fibrillation but had a known risk factor for stroke (eg, hypertension, diabetes, heart failure, and history of stroke) were included; Then a baseline electrocardiogram was used to exclude patients with atrial fibrillation. Patients were randomized (1:3) to receive either ILR with remote monitoring or usual care. Patients were followed up with in-person study visits for at least 3 years, with a median follow-up period of 65 months (interquartile range 59–70 months). The stroke prognosis was assessed by a panel of expert clinicians and subsequently pooled based on length of hospital stay and severity at presentation.

The overall stroke rate in the control group was 1.08 per 100 person-years (95% CI 0.95–1.23) and was 0.86 (0.67–1.10) per 100 person-years in the ILR group. The hazard ratio for stroke in the ILR group compared to the control group was 0.80 (0.61–1.05), which was not significantly different. The incidence of acute stroke was 40% in the control group and 35% in the intervention group. The hazard ratio for severe stroke between the groups was 0.69 (95% confidence interval 0.44-1.09). A subgroup analysis based on previous stroke history found that the intervention group may have a lower rate of ischemic stroke among patients without a previous history of stroke:hazard ratio 0.68 (0.48–0.97). The same is true for cardiac arrest, as indicated by the hazard ratio of 0.46 (0.22-0.97).

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