Normobaric Hypoxic Cardiac Rehabilitation: Comparative Effects of Training at 2000 m and 3000 m Simulated Altitude in...

Background: Coronary artery disease remains the leading cause of morbidity and mortality in developed countries. Despite advances in treatment and standard rehabilitation, conventional programs may be monotonous and insufficiently engaging. Normobaric hypoxia, simulating high-altitude conditions, has emerged as a potential method to enhance cardiovascular adaptations in post-myocardial infarction (MI) patients. Objective: This study aimed to compare the efficacy and safety of exercise-based cardiac rehabilitation performed under normobaric hypoxia corresponding to altitudes of 2000 m and 3000 m above sea level in patients after MI treated with percutaneous coronary intervention (PCI). Methods: A total of 61 male post-MI patients (mean age 60.4 ± 8.9 years) were randomized into two groups: training under simulated altitudes of 2000 m (n = 35) or 3000 m (n = 26). The 22-day program consisted of interval ergometer sessions. Pre- and post-intervention assessments included cardiopulmonary exercise testing (CPET), echocardiography, and tissue Doppler imaging (TDI). Results: Both groups demonstrated significant improvements in exercise tolerance. Training at 2000 m significantly increased test duration (r = 0.735) and peak heart rate (r = 0.467). At 3000 m, additional benefits were observed, including improvements in metabolic equivalent (r = 0.861), peak oxygen consumption (d = 0.81), and reduction in respiratory exchange ratio (r = 0.682). Intergroup analysis revealed moderate differences favoring the 3000 m group in MET, breathing frequency, and RER. Echocardiography showed beneficial remodeling in both groups, with improvements in LV dimensions, ejection fraction, and MAPSE. Notably, training at 2000 m resulted in more consistent echocardiographic benefits compared to 3000 m. Conclusions: Cardiac rehabilitation under normobaric hypoxia is effective and safe in stable post-MI patients. Training at 3000 m provides greater improvements in exercise tolerance, while 2000 m confers more favorable effects on cardiac structure and function. These findings suggest that moderate hypoxic exposure (2000 m) may represent an optimal balance between efficacy and safety in post-MI rehabilitation.