The case report describes the case of a 28-year-old healthy man who developed high-altitude pulmonary edema (HAPE) after rapid ascent to high altitudes. During treatment, he was given corticosteroids, diuretics and supplemental oxygen, which led to an improvement in his condition. Two days after discontinuation of these medications, the patient developed symptomatic sinus bradycardia with a heart rate of 37 beats per minute. Bradycardia was due to return of vagus nerve tone and withdrawal of steroids during the recovery phase. The patient's condition improved after intravenous potassium supplementation and fluid resuscitation, with his heart rate returning to 59 beats per minute. The case highlights the need for increased clinical vigilance in monitoring patients during the recovery phase from high-altitude pulmonary edema, as severe cardiac arrhythmias may occur during this period.