Low Cardiac Output Augmentation during Exercise Stress Echocardiography at Low Altitude Predicts High Risk of Acute Mountain Sickness.

OBJECTIVE

Stress-induced changes in echocardiographic parameters reflect cardiac reserve function. This study aimed to identify predictors of acute mountain sickness (AMS) using exercise stress echocardiography (ESE) before ascent.

METHODS

In this prospective cohort study, 104 healthy adults were enrolled and treated using ESE using a mechanically braked bicycle ergometer at a low altitude (LA) (500 m). Physiological data and echocardiographic parameters were collected before and during exercise. An ascent from 500 m to 4,100 m was completed by the bus within two days. AMS was identified using the Lake Louise Questionnaire.

RESULTS

Among the 104 participants, 49 developed AMS at 4,100 m. Compared with individuals without AMS, those with AMS had a higher low-altitude (500 m) heart rate (HR) but lower stroke volume (SV) at rest, lower cardiac output (CO) and SV during exercise, and lower rates of change in CO, SV, and HR. Multivariate regression analysis revealed that female sex (odds ratio [ OR] = 3.17, P = 0.039) and the rate of change in CO during exercise ( OR = 0.98, P = 0.001) were independent risk factors for AMS. Participants with the lowest CO change rate after ESE presented the highest AMS risk.

CONCLUSION

ESE could serve as an effective screening tool for AMS susceptibility, and blunted CO augmentation during exercise is an independent predictive marker for AMS risk.