The former Ryder Cup captain, who won 10 European Tour titles, collapsed while giving an after-dinner speech at an Aberdeen hotel.
The 64-year-old says he survived thanks to quick-thinking medics who arrived on the scene, and nurses who were in the room.
"Three nurses gave me immediate help," he explained. "The Marcliffe Hotel had a defibrillator on site which was incredibly lucky. If it hadn't been there I wouldn't be here. These people saved my life."
The father of television presenter Kirsty Gallacher, he was released from hospital on Friday and is recovering at home in London.
"I had no pain, no warning of what was coming," he said. "People said I suddenly collapsed. They said it looked like I'd been floored by a boxer."
Doctors at Aberdeen Royal Infirmary lowered his body temperature in a process called therapeutic hypothermia to save his brain from injury before implanting a defibrillator in his chest to re-start his heart automatically if it stops again.
"Family, friends and even total strangers kept us going," he said. Among well-wishers were his old friend, the Strictly Come Dancing host Bruce Forsyth, and golfer Tony Jacklin, a contestant on the show.