ImportanceArterial hypoxemia, electrolyte imbalances, and periodic breathing increase the vulnerability to cardiac arrhythmia at altitude.ObjectiveTo explore the incidence of tachyarrhythmias and bradyarrhythmias in healthy individuals at high altitudes.Design, Setting, and ParticipantsThis prospective cohort study involved healthy individuals at altitude (8849 m) on Mount Everest, Nepal. Recruitment occurred from January 25 to May 9, 2023, and data analysis took place from June to July 2023.ExposureAll study participants underwent 12-lead electrocardiogram, transthoracic echocardiography, and exercise stress testing before and ambulatory rhythm recording both before and during the expedition.Main OutcomeThe incidence of a composite of supraventricular (>30 seconds) and ventricular (>3 beats) tachyarrhythmia and bradyarrhythmia (sinoatrial arrest, second- or third-degree atrioventricular block).ResultsOf the 41 individuals recruited, 100% were male, and the mean (SD) age was 33.6 (8.9) years. On baseline investigations, there were no signs of exertional ischemia, wall motion abnormality, or cardiac arrhythmia in any of the participants. Among 34 individuals reaching basecamp at 5300 m, 32 participants climbed to 7900 m or higher, and 14 reached the summit of Mount Everest. A total of 45 primary end point–relevant events were recorded in 13 individuals (38.2%). Forty-three bradyarrhythmic events were documented in 13 individuals (38.2%) and 2 ventricular tachycardias in 2 individuals (5.9%). Nine arrhythmias (20%) in 5 participants occurred when climbers were using supplemental bottled oxygen, whereas 36 events (80%) in 11 participants occurred at lower altitudes when no supplemental bottled oxygen was used. The proportion of individuals with arrhythmia remained stable across levels of increasing altitude, while event rates per 24 hours numerically increased between 5300 m (0.16 per 24 hours) and 7300 m (0.37 per 24 hours) before decreasing again at higher altitudes, where supplemental oxygen was used. None of the study participants reported dizziness or syncope.Conclusion and RelevanceIn this study, more than 1 in 3 healthy individuals experienced cardiac arrhythmia during the climb of Mount Everest, thereby confirming the association between exposure to high altitude and incidence of cardiac arrhythmia. Future studies should explore the potential implications of these rhythm disturbances.

中文翻译：

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珠穆朗玛峰登山者的心律失常风险

重要性动脉低氧血症、电解质失衡和周期性呼吸会增加高原地区发生心律失常的可能性。目的探讨高海拔地区健康个体快速性心律失常和缓慢性心律失常的发生率。设计、设置和参与者这项前瞻性队列研究涉及高原地区的健康个体（8849 m） ）在尼泊尔珠穆朗玛峰。招募时间为2023年1月25日至5月9日，数据分析时间为2023年6月至7月。暴露所有研究参与者在探险前和探险期间均接受了12导联心电图、经胸超声心动图和运动压力测试以及动态节律记录。主要结果室上性（>30秒）和室性（>3次搏动）快速性心律失常和缓慢性心律失常（窦房停搏、二度或三度房室传导阻滞）的发生率。 结果在招募的 41 名个体中，100 名% 为男性，平均 (SD) 年龄为 33.6 (8.9) 岁。在基线调查中，任何参与者都没有出现劳力性缺血、室壁运动异常或心律失常的迹象。到达5300m大本营的34人中，有32人攀登到7900m以上，其中14人登顶珠穆朗玛峰。 13 人 (38.2%) 总共记录了 45 个主要终点相关事件。 13 名个体 (38.2%) 记录了 43 起缓慢心律失常事件，2 名个体 (5.9%) 记录了 2 起室性心动过速事件。当登山者使用补充瓶装氧气时，5 名参与者发生了 9 起心律失常 (20%)，而在不使用补充瓶装氧气的低海拔地区，11 名参与者发生了 36 起心律失常 (80%)。随着海拔的升高，心律失常患者的比例保持稳定，而在 5300 m（每 24 小时 0.16 次）和 7300 m（每 24 小时 0.37 次）之间，每 24 小时的事件发生率在数值上有所增加，然后在更高海拔（补充氧气）再次下降。被使用了。没有研究参与者报告头晕或晕厥。结论和相关性在这项研究中，超过三分之一的健康人在攀登珠穆朗玛峰期间经历过心律失常，从而证实了暴露在高海拔地区与心律失常发生率之间的关联。未来的研究应该探索这些节律紊乱的潜在影响。