Assessment of Cardiac Arrhythmias at Extreme High Altitude Using an Implantable Cardiac Monitor
REVEAL HA Study (REVEAL High Altitude)
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It has been suggested, although still unproven, that exposure at high altitude (HA) is proarrhythmic and could potentially contribute to an increased risk of sudden cardiac death.1,2 However, limited data are available to substantiate this claim, particularly at >5000 m. We hypothesized that extreme HA leads to an increased risk of pathological cardiac tachyarrhythmias, detected using an implantable cardiac monitor (ICM).
Sixteen healthy adult white male British military servicemen underwent continuous ECG monitoring using a Reveal LINQ ICM (Medtronic Ltd) for ≥7 weeks before, during, and >8 weeks after an attempted summit of Mount Dhaulagiri (8167 m). They were required to have a normal 12-lead ECG and transthoracic echocardiogram at recruitment and were excluded if they had a history of cardiac arrhythmia. They underwent written informed consent, and the study was approved by the Ministry of Defense Research and Medical Ethics Committee. The participants flew from the United Kingdom to Kathmandu, Nepal (1400 m, days 1–2), then by road (days 3–4) to 2679 m. Thereafter, they trekked carrying moderate loads to 3720 m (day …