Between hypothermia and hypoxia — not to mention the risk of an avalanche and rockfalls — summiting Mount Everest pushes the human body to its limits.

Swiss and Nepalese researchers now report that mountaineers who attempt the peak can add an elevated risk of cardiac arrhythmias to the list of challenges.

“In this study, more than one in three healthy individuals experienced cardiac arrhythmia during the climb of Mount Everest, thereby confirming the association between exposure to high altitude and incidence of cardiac arrhythmia,” the authors wrote.

“Future studies should explore the potential implications of these rhythm disturbances.”