There is no good place to have a heart attack. But at nearly 20,000 feet clinging to a wall of ice near the summit of a remote mountain in the Himalayas has to rank up there as one of the worst places to suffer a coronary.

Veteran mountain climber Conrad Anker at age 54 was five pitches away from reaching the summit of 22,660-foot Lunag-Ri in Nepal with his 26-year-old climbing partner Austrian David Lama when his chest started to not feel right. The pair was attempting to be the first climbers to reach the untouched summit.

“Realizing this was not a pulmonary or cerebral reaction to altitude, we immediately rappelled. Having never experienced anything of this nature I immediately understood this as a time critical health situation. We called for a helicopter and with the help of our Sherpa friends I was evacuated to Kathmandu,” Anker wrote on Facebook. 

Anker clearly understands his body well and for good reason having spent so much at altitude pushing himself to the limit. Four years ago he summitted Everest without oxygen and was studied by researchers for the effects. More recently he climbed Meru in the Himalayas and documented the ascent with two others in the hit film Meru in 2015.

Anker is no stranger to danger either. In 1999, he and two other climbing partners were swept up in an avalanche with only Anker surviving. He lost his best friend Alex Lowe in the accident, who’s body was recovered just last year.

Following the evacuation and arrival at the hospital, Anker was treated with an angioplasty and doctors removed the obstruction. The incident took place on Nov 16 and Anker is said to be recovering well. In short order, he says, he’ll back on the mountain.

To read more about the story visit National Geographic.