May lay prone and the crowd was aghast.
Officials rushed to assist, as did fellow driver Ellie Barron. A qualified physiotherapist, Barron performed CPR on May while a couple of doctors came from the crowd.
The Otago Regional Rescue Helicopter arrived swiftly and May was taken to Dunedin Hospital.
He said he had no recollection of the event.
"I don't remember a thing. I can't remember anything about it. I can remember race three but that is it," he said.
"All I can get from it is what people have told me. I got flown to Dunedin for four or five days then transferred up to Christchurch Hospital where a defibrillator was fitted for me."
Doctors told him he died for 10 minutes on the course but was brought back.
May was back racing in just over six months, but he said he was lucky to be in the right place at the right time when the incident happened.
"Most people die of it. They say only 5% of people live from it. But I was extremely lucky it happened where it did. I was surrounded by all these great people who kept me alive ... If I had been out in the middle of the paddock on a header then I'd have had no chance."
May's heart had stopped suddenly. The official diagnosis was hypertrophic obstructive cardiomyopathy, a genetic condition where heart muscles thicken, making it hard for the heart to operate.
"It was not a heart attack like a lot of people thought. The muscle in my heart just cut all the circulation off."
May said his uncle died of what was thought to be a heart attack at age 31, but it was probably hypertrophic obstructive cardiomyopathy.
He had to take a pill every day for it and his children had been tested.
May was "looking forward, not looking back" and was aiming to get to 3000 wins — he was about 30 wins short — and then it might be a time to slow down and work full-time on his cropping farm in Methven.
But he still looks forward to returning to Omakau to repay the club.
"I sort of have to go back, really. I ruined the meeting for them last time out."
