研究背景：

约有半数的晕厥患者即使经过全面的晕厥评估流程，也很难做出明确的诊断。植入式循环记录仪（implantable loop recorder, ILR）可提供连续的动态心电图监测。ILR可以通过延长监测时间，提高发作性心律失常被记录的概率，与西方国家相比，中国对ILR的研究起步较晚，基于亚洲人群的ILR诊断数据有限。

研究方法：

本研究为单中心、前瞻性队列研究，连续纳入2016年1月1日至2022年12月31日因晕厥住院诊疗后仍不能明确诊断的不明原因晕厥（unexplained syncope，US）患者227例。依据是否同意接受ILR植入监测将入选患者分为ILR植入组和传统随访组。主要终点定义为通过ILR监测或传统检查方法得出的确定性诊断。次要终点定义为通过ILR监测或传统检查方法得出的提示性诊断。采用Kaplan-Meier曲线分析3年监测期间确定性诊断的发生情况。采用Cox比例风险模型确定监测期间确定性心律失常诊断的独立预测因素。

研究结果：

本部分研究共入选2016年1月1日至2022年12月31日于北京医院因晕厥住院后仍不能明确诊断的US患者227例，平均年龄65.9 ± 12.8岁，男性患者112例（49.3%）。ILR植入组患者127例（55.9%），传统随访组患者100例（44.1%）。2组间比较，ILR植入组患者较传统随访组年龄偏大（P＜0.001）。随访期间ILR植入组中共有59例（46.5%）确诊CS，传统随访组中共有5例（5.0%）US患者确诊CS。ILR植入组中13例（10.2%）US患者获得可疑的CS提示性诊断，传统随访组中仅有1例（1.0%）患者检测到提示性心律失常，具有显著差异（P<0.001）。Kaplan‑Meier生存曲线比较两组患者间的CS累计诊断率，结果显示，与传统随访组相比，ILR植入组患者CS累计诊断率更高（HR=11.000，95% CI 6.737 - 17.963，log‑rank P<0.001）。多因素Cox回归分析结果显示ILR植入（HR=10.897，95% CI 3.852 - 30.831，P<0.001）、年龄≥60岁（HR=3.224，95% CI 1.239 - 8.389，P=0.016）以及基线心电图存在一度房室传导阻滞（atrioventricular block，AVB）（HR=2.505，95% CI 1.282 - 4.897，P=0.007）是US患者明确诊断CS的独立预测因素。

研究结论：

本部分研究通过对US患者进行长时间随访发现，ILR可以显著提高US患者的晕厥诊断效力，有助于早期识别CS高风险患者。

Background

  Approximately half of patients with syncope remain inconclusive even after comprehensive diagnostic workup. Implantable loop recorders (ILRs) provide continuous ambulatory electrocardiographic monitoring, significantly improving the diagnostic rate of heart rhythm disorders. Compared with Western countries, data on diagnosis of Chinese population with ILR are limited.

Methods

This single-center, prospective cohort study consecutively enrolled 227 patients with unexplained syncope (US) from January 2016 to December 2022. Participants were divided into two groups based on their decision for receiving ILR implantation: ILR group and conventional follow-up group. The primary endpoint was defined as a definitive diagnosis established by ILR monitoring or conventional follow-up. The secondary endpoint was defined as a suggestive diagnosis reached by ILR monitoring or conventional follow-up. The occurrence of a diagnostic event during follow-up was analysed by Kaplan–Meier method. Multivariate Cox analysis was conducted to identify risk factors for definitive arrhythmia diagnosis during follow-up.

Results

  This study enrolled 227 patients with US from January 2016 to December 2022 (mean age 65.9 ± 12.8 years, 43.9% male). Patients were divided into ILR group (n=127, 55.9%) and conventional follow-up group (n=100, 44.1%). Compared to conventional follow-up group, patients in ILR group were significantly older than conventional follow-up group (P<0.001). During follow-up, conclusive arrhythmias were de novo detected in 59 patients (46.5%) in ILR group and 5 patients (5.0%) in conventional follow-up group. Suggestive diagnosis was recorded in 13 patients (10.2%) in ILR group and 2 patients in conventional follow-up group. The diagnosis rate of CS in ILR group was higher than that in the conventional follow‑up group (all P<0.001). Kaplan‑Meier survival analysis showed that the cumulative diagnostic rate of CS was significantly higher in ILR group than in traditional follow‑up group (HR=11.000, 95% CI 6.737-17.963, log-rank P<0.001). Multivariate Cox analysis indicated that ICM implantation (HR=10.897，95% CI 3.852 - 30.831，P<0.001), age ≥60 years (HR=3.224，95% CI 1.239 - 8.389，P=0.016) or first-degree atrioventricular block (AVB) (HR=2.505，95% CI 1.282 - 4.897，P=0.007) in baseline electrocardiogram were independent predictors for CS.

Conclusion

  This study demonstrated that ILR monitoring significantly improved diagnostic rate of CS in patients with US and facilitates early identification of high-risk CS patients.