Background

It is unknown whether screening for atrial fibrillation and subsequent treatment with anticoagulants if atrial fibrillation is detected can prevent stroke. Continuous electrocardiographic monitoring using an implantable loop recorder (ILR) can facilitate detection of asymptomatic atrial fibrillation episodes. We aimed to investigate whether atrial fibrillation screening and use of anticoagulants can prevent stroke in individuals at high risk.

Methods

We did a randomised controlled trial in four centres in Denmark. We included individuals without atrial fibrillation, aged 70–90 years, with at least one additional stroke risk factor (ie, hypertension, diabetes, previous stroke, or heart failure). Participants were randomly assigned in a 1:3 ratio to ILR monitoring or usual care (control) via an online system in permuted blocks with block sizes of four or eight participants stratified according to centre. In the ILR group, anticoagulation was recommended if atrial fibrillation episodes lasted 6 min or longer. The primary outcome was time to first stroke or systemic arterial embolism. This study is registered with ClinicalTrials.gov, NCT02036450.

Findings

From Jan 31, 2014, to May 17, 2016, 6205 individuals were screened for inclusion, of whom 6004 were included and randomly assigned: 1501 (25·0%) to ILR monitoring and 4503 (75·0%) to usual care. Mean age was 74·7 years (SD 4·1), 2837 (47·3%) were women, and 5444 (90·7%) had hypertension. No participants were lost to follow-up. During a median follow-up of 64·5 months (IQR 59·3–69·8), atrial fibrillation was diagnosed in 1027 participants: 477 (31·8%) of 1501 in the ILR group versus 550 (12·2%) of 4503 in the control group (hazard ratio [HR] 3·17 [95% CI 2·81–3·59]; p<0·0001). Oral anticoagulation was initiated in 1036 participants: 445 (29·7%) in the ILR group versus 591 (13·1%) in the control group (HR 2·72 [95% CI 2·41–3·08]; p<0·0001), and the primary outcome occurred in 318 participants (315 stroke, three systemic arterial embolism): 67 (4·5%) in the ILR group versus 251 (5·6%) in the control group (HR 0·80 [95% CI 0·61–1·05]; p=0·11). Major bleeding occurred in 221 participants: 65 (4·3%) in the ILR group versus 156 (3·5%) in the control group (HR 1·26 [95% CI 0·95–1·69]; p=0·11).

Interpretation

In individuals with stroke risk factors, ILR screening resulted in a three-times increase in atrial fibrillation detection and anticoagulation initiation but no significant reduction in the risk of stroke or systemic arterial embolism. These findings might imply that not all atrial fibrillation is worth screening for, and not all screen-detected atrial fibrillation merits anticoagulation.

Funding

Innovation Fund Denmark, The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation, Aalborg University Talent Management Program, Arvid Nilssons Fond, Skibsreder Per Henriksen, R og Hustrus Fond, The AFFECT-EU Consortium (EU Horizon 2020), Læge Sophus Carl Emil Friis og hustru Olga Doris Friis' Legat, and Medtronic.

中文翻译：

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植入式循环记录器检测心房颤动以预防中风（循环研究）：一项随机对照试验

背景

目前尚不清楚是否筛查房颤并在检测到房颤后使用抗凝剂进行后续治疗可以预防中风。使用植入式循环记录器 (ILR) 进行连续心电图监测可以促进无症状心房颤动发作的检测。我们旨在调查房颤筛查和抗凝剂的使用是否可以预防高危人群的卒中。

方法

我们在丹麦的四个中心进行了一项随机对照试验。我们纳入了年龄在 70-90 岁、至少有一个额外卒中危险因素（即高血压、糖尿病、既往卒中或心力衰竭）的无房颤个体。参与者通过在线系统以 1:3 的比例被随机分配到 ILR 监测或常规护理（控制），按中心分层排列的块大小为 4 或 8 名参与者。在 ILR 组中，如果心房颤动发作持续 6 分钟或更长时间，则推荐抗凝治疗。主要结果是首次中风或全身动脉栓塞的时间。该研究已在 ClinicalTrials.gov 注册，NCT02036450。

发现

从 2014 年 1 月 31 日到 2016 年 5 月 17 日，共筛选了 6205 人，其中 6004 人被纳入并随机分配：1501 人 (25·0%) 接受 ILR 监测，4503 人 (75·0%) 接受常规护理。平均年龄为 74·7 岁（SD 4·1），2837 人（47·3%）为女性，5444 人（90·7%）患有高血压。没有参与者失访。在 64·5 个月（IQR 59·3–69·8）的中位随访期间，1027 名参与者被诊断为心房颤动：ILR 组 1501 名参与者中有 477 名（31·8%）与 550 名（12·2%） ) 为对照组的 4503 人（风险比 [HR] 3·17 [95% CI 2·81–3·59]；p<0·0001）。1036 名参与者开始口服抗凝治疗：ILR 组 445 人（29·7%），对照组 591 人（13·1%）（HR 2·72 [95% CI 2·41-3·08]；p <0·0001)，主要结局发生在 318 名参与者中（315 名中风，3 名全身动脉栓塞）：ILR 组为 67 (4·5%)，而对照组为 251 (5·6%) (HR 0·80 [95% CI 0·61–1·05]；p=0·11)。221 名参与者发生大出血：ILR 组 65 人 (4·3%)，对照组 156 人 (3·5%) (HR 1·26 [95% CI 0·95–1·69]；p= 0·11)。

解释

在有卒中危险因素的个体中，ILR 筛查使房颤检测和抗凝治疗增加了三倍，但卒中或全身动脉栓塞的风险没有显着降低。这些发现可能意味着并非所有心房颤动都值得筛查，也并非所有筛查检测到的心房颤动都值得抗凝。

资金

丹麦创新基金、丹麦首都地区研究基金会、丹麦心脏基金会、奥尔堡大学人才管理计划、Arvid Nilssons Fond、Skibsreder Per Henriksen、R og Hustrus Fond、The AFFECT-EU Consortium (EU Horizo​​n 2020)、Læge Sophus Carl Emil Friis og hustru Olga Doris Friis' Legat 和 Medtronic。