Exercise in hypoxia: a model from laboratory to on field studies

Clinical outcome and quality of life of chronic heart failure (HF) patients have greatly improved over the last two decades. These results and the availability of modern lifts allow many cardiac patients to spend leisure time at altitude. HF per se doesn’t impede a safe stay at altitude, but exercise at both simulated and real altitude is associated with a reduction in performance, which is inversely proportional to HF severity. For example, in normal subjects, the reduction in functional capacity is ∼2% every 1000 m altitude increase, whereas it is 4% and 10% in HF patients with normal or slightly diminished exercise capacity and in HF patients with markedly diminished exercise capacity. Also the on-field experience with HF patients at altitude confirm safety and shows overall similar data to that reported at simulated altitude. Even “optimal” HF treatment in patients spending time at altitude or at hypoxic conditions is likely different from optimal treatment at sea level, particularly as regards β-blockers selectivity. Furthermore, high altitude, both simulated or on-field, represents a stimulating model of hypoxia in HF patients and healthy subjects. Our data suggest that spending time at altitude (<3500 m) can be safe even for HF patients, provided that subjects are free of co-morbidities that may directly interfere with the adaptation to altitude and are stable. However, HF patients experience a reduction of exercise capacity directly proportional to HF severity and altitude. Finally, HF patients should be tested for functional capacity and undergo a specific “hypoxictailored treatment” to avoid pharmacological interference with altitude adaptation mechanisms, particularly with regard to the selectivity of beta-blockers.