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What is the rate of detection of atrial fibrillation with use of an implantable electrocardiographic monitor for 12 months vs use of prolonged external electrocardiographic monitoring for 30 days after an ischemic stroke?
In this randomized clinical trial that included 300 patients, the rate of detection of atrial fibrillation or flutter lasting 2 minutes or longer by 12 months was 15.3% in the implantable loop recorder group vs 4.7% in the prolonged external loop recorder group, a statistically significant difference.
Among patients with ischemic stroke, implantable electrocardiographic monitoring for 12 months resulted in the detection of more patients with atrial fibrillation compared with prolonged external monitoring for 30 days, although further research is needed to better understand clinical outcomes and cost-effectiveness.
The relative rates of detection of atrial fibrillation (AF) or atrial flutter from evaluating patients with prolonged electrocardiographic monitoring with an external loop recorder or implantable loop recorder after an ischemic stroke are unknown.
To determine, in patients with a recent ischemic stroke, whether 12 months of implantable loop recorder monitoring detects more occurrences of AF compared with conventional external loop recorder monitoring for 30 days.
Design, Setting, and Participants
Investigator-initiated, open-label, randomized clinical trial conducted at 2 university hospitals and 1 community hospital in Alberta, Canada, including 300 patients within 6 months of ischemic stroke and without known AF from May 2015 through November 2017; final follow-up was in December 2018.
Participants were randomly assigned 1:1 to prolonged electrocardiographic monitoring with either an implantable loop recorder (n = 150) or an external loop recorder (n = 150) with follow-up visits at 30 days, 6 months, and 12 months.
Main Outcomes and Measures
The primary outcome was the development of definite AF or highly probable AF (adjudicated new AF lasting ≥2 minutes within 12 months of randomization). There were 8 prespecified secondary outcomes including time to event analysis of new AF, recurrent ischemic stroke, intracerebral hemorrhage, death, and device-related serious adverse events within 12 months.
Among the 300 patients who were randomized (median age, 64.1 years [interquartile range, 56.1 to 73.7 years]; 121 were women [40.3%]; and 66.3% had a stroke of undetermined etiology with a median CHA2DS2-VASc [congestive heart failure, hypertension, age ≥75 years, diabetes, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, sex category] score of 4 [interquartile range, 3 to 5]), 273 (91.0%) completed cardiac monitoring lasting 24 hours or longer and 259 (86.3%) completed both the assigned monitoring and 12-month follow-up visit. The primary outcome was observed in 15.3% (23/150) of patients in the implantable loop recorder group and 4.7% (7/150) of patients in the external loop recorder group (between-group difference, 10.7% [95% CI, 4.0% to 17.3%]; risk ratio, 3.29 [95% CI, 1.45 to 7.42]; P = .003). Of the 8 specified secondary outcomes, 6 were not significantly different. There were 5 patients (3.3%) in the implantable loop recorder group who had recurrent ischemic stroke vs 8 patients (5.3%) in the external loop recorder group (between-group difference, −2.0% [95% CI, −6.6% to 2.6%]), 1 (0.7%) vs 1 (0.7%), respectively, who had intracerebral hemorrhage (between-group difference, 0% [95% CI, −1.8% to 1.8%]), 3 (2.0%) vs 3 (2.0%) who died (between-group difference, 0% [95% CI, −3.2% to 3.2%]), and 1 (0.7%) vs 0 (0%) who had device-related serious adverse events.
Conclusions and Relevance
Among patients with ischemic stroke and no prior evidence of AF, implantable electrocardiographic monitoring for 12 months, compared with prolonged external monitoring for 30 days, resulted in a significantly greater proportion of patients with AF detected over 12 months. Further research is needed to compare clinical outcomes associated with these monitoring strategies and relative cost-effectiveness.
ClinicalTrials.gov Identifier: NCT02428140
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CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.
Corresponding Author: Brian H. Buck, MD, MSc, Division of Neurology, Department of Medicine, University of Alberta, 7-112H Clinical Sciences Bldg, 11350-83 Ave NW, Edmonton, AB T6G2G3, Canada (firstname.lastname@example.org).
Accepted for Publication: April 4, 2021.
Author Contributions: Drs Buck and Hill had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Buck, Hill, Quinn, Butcher, Menon, Gulamhusein, Barber, Demchuk, Shuaib, Exner.
Acquisition, analysis, or interpretation of data: Buck, Hill, Quinn, Butcher, Menon, Siddiqui, Coutts, Jeerakathil, Smith, Khan, Barber, Jickling, Reyes, Save, Fairall, Piquette, Kamal, Chew, Demchuk, Shuaib.
Drafting of the manuscript: Buck, Khan, Barber, Reyes, Exner.
Critical revision of the manuscript for important intellectual content: Buck, Hill, Quinn, Butcher, Menon, Gulamhusein, Siddiqui, Coutts, Jeerakathil, Smith, Khan, Barber, Jickling, Save, Fairall, Piquette, Kamal, Chew, Demchuk, Shuaib, Exner.
Statistical analysis: Buck, Hill, Menon.
Obtained funding: Buck, Hill, Demchuk, Exner.
Administrative, technical, or material support: Buck, Hill, Menon, Gulamhusein, Jeerakathil, Khan, Reyes, Save, Fairall, Piquette, Kamal, Demchuk, Shuaib, Exner.
Supervision: Buck, Hill, Gulamhusein, Exner.
Conflict of Interest Disclosures: Dr Buck reported receiving research funding from Alberta Innovates Health Solutions. Dr Hill reported receiving grants from NoNO Inc, Boehringer Ingelheim Canada, Medtronic LLC; receiving personal fees from Sun Pharma; being involved in a US patent licensed to Circle Neurovascular Inc; and serving as director for Circle Neurovascular Inc, the Canadian Stroke Consortium, and the Canadian Neuroscience Federation. Dr Quinn reported receiving personal fees from Bristol-Myers Squibb/Pfizer; and receiving grants from Bayer. Dr Butcher reported receiving personal fees from Medtronic, Boehringer-Ingelheim, Servier, Bayer, and Bristol-Myers Squibb/Pfizer; and receiving grants or other research funding from Boehringer-Ingelheim, Bayer, Pfizer, Servier Canada, and Bristol-Myers Squibb/Pfizer. Dr Menon reported holding shares in Circle NVI. Dr Smith reported receiving consulting fees from Alnylam, Biogen, Bayer, and Javelin; and receiving royalties from UpToDate. Dr Jickling reported receiving grants from the Canadian Institutes of Health Research and the Heart and Stroke Foundation of Canada. Dr Kamal reported receiving personal fees for serving as part owner of DESTINE Health Inc; and receiving grants from the Canadian Institutes of Health Research. Dr Demchuk reported receiving personal fees from Bristol-Myers Squibb/Pfizer. Dr Exner reported being chief medical officer and minority shareholder in HelpWear Inc; receiving consulting fees and research funding from Abbott Medical, Boston Scientific, GE Healthcare, and Medtronic Inc; and receiving nonfinancial support and having stock options in Analytics for Life. No other disclosures were reported.
Funding/Suppport: This study was supported by Alberta Innovates Health Solutions Collaborative Research and Innovations Opportunities and by grant 201300474 from the Partnership for Research and Innovation in the Health System, government of Alberta. Unrestricted in-kind support (implantable loop recorder devices and the electrocardiographic core laboratory) was provided by Medtronic Canada.
Role of the Funder/Sponsor: The funders/sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Data Sharing Statement: See Supplement 4.
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