Effect of ubiquinol on electrophysiology during high-altitude acclimatization and de-acclimatization: A substudy of the Shigatse CARdiorespiratory fitness (SCARF) randomized clinical trial.

High-altitude exposure changes the electrical conduction of the heart. However, reports on electrocardiogram (ECG) characteristics and potent prophylactic agents during high-altitude acclimatization and de-acclimatization are inadequate. This study aimed to investigate the effects of ubiquinol on electrophysiology after high-altitude hypoxia and reoxygenation. The study was a prospective, randomized, double-blind, placebo-controlled trial. Forty-one participants were randomly divided into two groups receiving ubiquinol 200 mg daily or placebo orally 14 days before flying to high altitude (3900 m) until the end of the study. Cardiopulmonary exercise testing was performed at baseline (300 m), on the third day after reaching high altitude, and on the seventh day after returning to baseline. Acute high-altitude exposure prolonged resting ventricular repolarization, represented by increased corrected QT interval (455.9 ± 23.4 vs. 427.1 ± 19.1 ms, P < 0.001) and corrected T peak -T end interval (155.5 ± 27.4 vs. 125.3 ± 21.1 ms, P < 0.001), which recovered after returning to low altitude. Ubiquinol supplementation shortened the hypoxia-induced extended T peak -T end interval (−7.7 ms, [95% confidence interval (CI), −13.8 to −1.6], P = 0.014), T peak -T end /QT interval (−0.014 [95% CI, −0.027 to −0.002], P = 0.028), and reserved maximal heart rate (11.9 bpm [95% CI, 3.2 to 20.6], P = 0.013) during exercise at high altitude. Furthermore, the decreased resting amplitude of the ST-segment in the V3 lead was correlated with decreased peak oxygen pulse (R = 0.713, P < 0.001) and maximum oxygen consumption (R = 0.595, P < 0.001). Our results illustrated the electrophysiology changes during high-altitude acclimatization and de-acclimatization. Similarly, ubiquinol supplementation shortened the prolonged T peak -T end interval and reserved maximal heart rate during exercise at high altitude. URL: www.chictr.org.cn ; Unique identifier: ChiCTR2200059900 • Short-term exposure to hypoxia did not cause sustained changes in the ECG. • Ubiquinol could shorten the hypoxia-induced extended ventricular repolarization. • The rest ST-segment amplitude in V3 could predict exercise capacity under hypoxia. [ABSTRACT FROM AUTHOR]