When Stanton Truxillo collapsed in the road while bicycling last month, someone leaped out of a car and performed cardio pulmonary resuscitation on him.

Truxillo, former president of the Austin Cycling Association, is home now, recovering after quadruple bypass surgery. But he still doesn’t know who kept his heart pumping in those crucial moments after he suffered a massive heart attack.

Truxillo was pedaling along a 40-mile route from Mozart’s coffee shop on Lake Austin Boulevard to Creedmore and back on Aug. 3 when he started feeling un-well.

“It was nothing specific, maybe a little heartburn,” Truxillo said this week by phone from his home.

The group had strung out on Old Lockhart Road when he told some of his fellow cyclists that he was going to stop and call for a ride home.

For Truxillo, that’s unheard of. His buddies knew something was seriously wrong.

A few seconds later, Truxillo knew he had to stop immediately. That’s when he blacked out, collapsing onto another cyclist and crashing to the ground on Slaughter Road.

Someone unclipped him from his pedals. None of the cyclists with him knew CPR. While one of them called 911, another ran into traffic and started stopping cars, asking if anyone knew CPR.

Someone did.

That person jumped out of his car and came to Truxillo’s aid.

“It was so fast that he was starting CPR before the 911 operator even answered the phone,” Truxillo says.

The man was performing CPR when the first emergency vehicle arrived and continued pumping Truxillo’s heart for him until a second emergency vehicle showed up.

Then he stepped back into his car and drove anonymously away.

“I have no idea who this Good Samaritan is,” Truxillo says.

Truxillo was rushed to St. David’s South Austin Hospital, where doctors put him into an induced coma for a day and a half. A week after he came out of the coma, he had quadruple bypass surgery.

“By all odds I should have been dead,” he says. “But doctors said my fitness had a major bit to play in my surviving.”

Truxillo, 69, has been cycling his entire adult life. He started as a child, commuted by bike through graduate school and his first few jobs, and raced for 15 or 20 years. He never stopped biking.

He had a history of high cholesterol and had been taking statins for the last five years.

Doctors tell him that after a few months of rehabilitation he should be back to normal. He hopes to be back on his bicycle in a few months.

And he hopes to find out who gave him CPR that Tuesday morning, so he can thank him.