High-altitude exercise stress echocardiography identifies individuals at risk for acute mountain sickness

Early identification of individuals vulnerable to acute mountain sickness (AMS) is clinically challenging. We hypothesized that exercise stress echocardiography (ESE), conducted within 6 h of arrival at 3,600 m following a staged ascent, could reveal distinctive right ventricular (RV) and pulmonary vascular responses predictive of AMS development.

Fifty healthy lowland residents completed a staged bus ascent to 3,600 m and underwent ESE within 6 h of arrival. Key measures included systolic pulmonary artery pressure (SPAP), pulmonary vascular resistance (PVR), tricuspid annular peak systolic velocity (TV s'), RV fractional area change (FAC), inferior vena cava (IVC) diameter, and mean PAP/cardiac output (CO) slope. AMS was assessed the next morning using the Lake Louise Score.

Of the participants, 23 (46%) met the criteria for AMS and 27 (54%) did not (non-AMS group). At peak exercise, the AMS group exhibited significantly higher SPAP (54.88 ± 7.89 vs. 46.71 ± 8.48 mmHg, p < 0.001) and PVR (2.24 ± 0.26 vs. 2.03 ± 0.17 WU, p = 0.001), accompanied by greater increases from rest in SPAP (20.42 ± 8.13 vs. 13.21 ± 6.22 mmHg, p = 0.015) and PVR (0.40 ± 0.19 vs. 0.30 ± 0.17 WU, p = 0.010). Conversely, the AMS group demonstrated impaired RV contractile reserve, reflected by smaller ΔTV s' (0.05 ± 0.04 vs. 0.08 ± 0.03 m/s, p = 0.006) and ΔFAC (8.26 ± 3.89 vs. 12.22 ± 5.35%, p = 0.033). IVC diameter was larger in the AMS group both at rest and during peak exercise (p = 0.047 and p = 0.018). A nomogram incorporating peak IVC diameter, ΔPVR, and ΔTV s' predicted AMS with an area under the curve (AUC) of 0.865 and an accuracy of 84.0%.

ESE identifies early differences in RV function, IVC dynamics, and pulmonary circulation in individuals susceptible to AMS within hours of arrival at high altitude following staged ascent. A model based on IVC-peak, ΔPVR, and ΔTV s' offers a practical tool for early AMS risk stratification.