[The heart and the mountains].

In a normal subject, exposure to high altitude is accompanied by a diminution in performance that is proportional to the hypoxia. In order to advise a cardiac patient who is contemplating undertaking a physical activity in the mountains and wishes to avoid taking any unnecessary risks in an environment that can quickly become very hostile, it is important to have a recent evaluation of the cardiopathy, and some appreciation of the expected problems linked to the activity and the location. Certain pathologies are absolute contraindications to high altitude, such as pulmonary arterial hypertension, thrombo-embolic disease, and unstable cardiac disease. The majority of stable cardiopathies allow some modified activity. The role of the cardiologist is to evaluate the patient's functional capacity, to calculate the effect of altitude on this capacity, and to postulate whether the reserve will be sufficient to cope with the expected demand.