Syncope in Patients with Cardiac Pacemakers

Abstract Introduction: It is challenging to diagnose syncope in patients with pacemakers. Because these patients have increased morbidity and mortality risks, they require immediate attention to determine the causes in order to provide appropriate treatment. This study aimed to investigate the causes and predictive factors of syncope as well as the methods used to diagnose syncope in cardiac pacemaker patients. Methods: Patients with pacemakers implanted owing to sinus node disease or atrioventricular block were evaluated with standardized questionnaires, endocavitary electrograms, and other tests based on the suspected causes of syncope. Mann-Whitney U tests were used to analyze continuous variables and Chi-squared or Fisher’s exact tests were used for categorical variables. Logistic regression was used for multivariate analyses. Statistical significance was P&lt;0.05. Results: The study included 95 patients with pacemakers: 47 experienced syncope in the last 12 months and 48 did not. Of the 100 documented episodes of syncope, 48.9% were vasovagal syncopes, 17% had cardiac-related causes, 10.6% had unknown causes, and 8.5% had pacemaker failure. The multivariate analysis showed that a New York Heart Association (NYHA) Functional Class II was a significant factor for developing syncope (P&lt;0.01). Conclusion: While the most common type of syncope in pacemaker patients was neurally mediated, it is important to perform detailed evaluations in this population as the causes of syncope can be life-threatening. The best diagnostic methods were stored electrogram analysis and the tilt table test. NYHA Functional Class II patients were found to have a higher risk for syncope.摘要与引言：心脏起搏器（pacemaker）植入患者的晕厥（syncope）诊断颇具挑战性。此类患者的发病与死亡风险均显著升高，需第一时间明确病因以实施针对性治疗。本研究旨在探究心脏起搏器植入患者的晕厥病因、预测因素及临床诊断方法。 方法：本研究纳入因窦房结疾病或房室传导阻滞植入心脏起搏器的患者，依据疑似晕厥病因，采用标准化问卷、心腔内电图（endocavitary electrogram）及其他针对性检查手段进行评估。连续变量采用曼-惠特尼U检验进行统计学分析，分类变量采用卡方检验或费希尔精确检验，多变量分析则采用逻辑回归模型，以P<0.05作为统计学显著性判定标准。 结果：本研究共纳入95名心脏起搏器植入患者，其中47名患者在过去12个月内出现过晕厥发作，48名未出现相关症状。在100次已记录的晕厥事件中，48.9%为血管迷走性晕厥，17%为心脏相关性病因所致，10.6%病因不明，8.5%由起搏器故障引发。多变量分析显示，纽约心脏协会（NYHA）心功能分级II级是晕厥发生的独立危险因素（P<0.01）。 结论：尽管心脏起搏器植入患者最常见的晕厥类型为神经介导性晕厥，但仍需对此类患者开展全面详细的评估，因为晕厥病因可能存在致命风险。最优的诊断方案为存储式心腔内电图分析与直立倾斜试验（tilt table test）。研究发现，NYHA心功能分级II级患者的晕厥发病风险显著更高。