Short-term Exposure to High Altitude in Patients With Asymptomatic Aortic Stenosis

Inclusion Criteria: Group 1: * Moderate or severe aortic stenosis (aortic valve area (AVA) ≤1.5 cm2) * NYHA class I * LVEF \> 50% * Aortic stenosis staging classification Stage 0 or 1 * Written informed consent Group 2: * Aortic stenosis s/p aortic valve replacement within 1 year * NYHA class I * LVEF \> 50% * Aortic stenosis staging classification Stage 0 or 1 * Written informed consent Group 3: * NYHA class I * LVEF \>50% * No evidence of valvular heart disease * Age \> 65 years * Written informed consent Exclusion Criteria: * NYHA class \> I (all groups) * History of cardiac decompensation requiring hospitalization (all groups) * Uncontrolled arterial hypertension (\>180/100 mmHg at rest) (all groups) * Other Cardiomyopathies w/ normal LVEF (dilatative, hypertrophic, infiltrative CMP) (all groups) * Signs of exercise-induced ischemia (ST-segment depression \> 2 mV), hemodynamic instability (drop in systolic blood pressure \> 20 mmHg and systolic blood pressure ≤ 100 mmHg), or ventricular arrhythmias (\> 5 beats) during cardiopulmonary stress exercise testing (CPET) at Bern (540 meters) (all groups) * Chronic obstructive pulmonary disease with a forced expiratory volume in 1 second (FEV1) \<60% of the predicted (all groups) * Known pulmonary hypertension with a pulmonary artery systolic pressure \>50 mmHg or high probability of pulmonary hypertension as assessed in TTE (all groups) * NT-pro BNP levels \> 900 pg/ml (all groups) * Aortic stenosis staging classification \> Stage 1 (group 1 and 2) * History of advanced stages of acute mountain sickness defined as high altitude pulmonary (HAPE) or cerebral (HACE) edema (all groups) * Transvalvular gradient across the aortic valve ≥60 mmHg, Vmax \>5 m/s (group 1) * Vmax progression ≥0.3 m/s/year (group 1) * Transvalvular gradient across the aortic valve ≥20 mmHg (group 2) * Evidence of valvular heart disease or coronary artery disease (group 3) * History of rhythm disturbances (other than premature ventricular contraction (PVC) (group 3) * Right ventricular dysfunction, defined as TAPSE \< 17 mm, s'DTI \< 9 cm/sec (all groups)