Short-term exposure to high altitude in patients with asymptomatic aortic stenosis
M R Bigler, A Zimmermann, D Berweger, F Schwarz, J Keller, D Hutter, C Dernektsi, M Wilhelm, T PilgrimAbstract
Background/Introduction
Aortic stenosis is a common disease with increasing prevalence due to an aging population. High altitude exposure for leisure activities and tourism is popular; however, in the absence of robust evidence, pathophysiological considerations have led to an expert consensus advising patients with aortic stenosis to avoid such exposure owing to a presumed elevated risk for myocardial ischemia and arrhythmia.
Purpose
The aim of this study is to evaluate the safety of short-time high altitude exposure in individuals with asymptomatic moderate to severe aortic stenosis.
Methods
This is an ongoing prospective, monocentric cohort study enrolling patients with asymptomatic moderate to severe aortic stenosis (n=20) and age- and sex-matched controls (n=20). All participants undergo baseline assessment at low altitude (540m.a.s.l.), including transthoracic echocardiography, cardiopulmonary exercise testing, and blood analysis. These evaluations are then repeated at high altitude (3454m.a.s.l.).
Results
To date, 8 out of the planned 20 aortic stenosis patients (100% male, mean age 74±10 years, mean aortic valve area 1.09±0.08cm2) have been enrolled. All patients successfully completed the evaluation at high altitude, and none required premature return to low altitude. High altitude exposure was associated with a marked decrease in resting oxygen saturation (SpO2 -9.2±3.6%), an associated more pronounced decrease during exercise (delta SpO2 -7.8±1.7%) and an increase in VE/VCO2 slope (+5.4±3.7), while exercise capacity (-5.5±15.7Watt, i.e. -4%) and peak VO2 remained largely stable (+0.8±2.6ml/min/kg). Echocardiographic assessment revealed increases in left ventricular filling pressure (E/e’ +1.4±4.1) and indexed cardiac output at rest (+0.8±0.9l/min/kg), while the mean transvalvular pressure gradient remained stable (-0.7±5.3mmHg). NTproBNP levels increased by +285±502pg/ml, representing a 118% rise.
Conclusion
Preliminary findings from this ongoing trial suggest that short term high-altitude exposure is well tolerated in individuals with asymptomatic moderate to severe aortic stenosis, even during physical exertion.Graphical abstract