Cardiovascular Alterations at High Altitude: A Systematic Review and Meta-Analysis.

Abstract

Objectives: The patterns of cardiovascular adaptation to high-altitude (HA) exposure remain unclear. The aim of this systematic review and meta-analysis was to characterize dose-dependent cardiovascular responses across altitude gradients and to identify the adaptive patterns associated with increasing altitude exposure.

Methods: We searched the MEDLINE, Embase, The Cochrane Library, WanFang Data, CNKI, VIP and CBM databases published from inception to April 2025. Studies assessing cardiovascular responses to high-altitude exposure were included. Data were synthesized using random-effects pairwise and dose-response network meta-analysis models, with standardized mean differences (SMDs) calculated for continuous outcomes. The study was prospectively registered in PROSPERO (CRD420251022814).

Results: We included 121 studies involving 108,530 participants in the final analysis. Compared with low-altitude group (LAG), peripheral capillary oxygen saturation declined in a dose-dependent manner, with a marked reduction at extreme high-altitude group (EHAG) (SMD, -16.68; 95% confidence interval [CI], -18.36 to -15.00). Diastolic blood pressure showed the greatest increase (SMD, 6.09; 95% CI, 4.71 to 7.47) at EHAG. Heart rate increased from LAG to HAG, but showed no further significant increase at higher altitudes. Subgroup analyses suggested variations in cardiovascular responses according to population type and exposure duration.

Conclusions: HA exposure induces altitude-dependent cardiovascular adaptations involving impaired oxygenation, hemodynamic changes, and cardiac remodeling, with more pronounced effects at EHAG. These findings offer evidence-based insights for clinical decision-making and formulation of altitude-specific healthcare policies.