“It’s amazing that it doesn’t happen more in sports,” Keegan Bradley, the 2011 P.G.A. Championship winner, said Monday.

There have been instances of players leaving the course in distress. During a competitive round in 2005, David Toms experienced a rapid heart rate that caused him to drop to a knee and clutch his chest. He was hospitalized and found to have supraventricular tachycardia, which he had surgery to correct. Robert Karlsson withdrew abruptly on the eve of this year’s British Open after experiencing the golf equivalent of an actor’s forgetting his lines: every time Karlsson tried to take the club back on his swings during a practice round, he froze.

Beljan came into the PGA Tour season finale ranked 139th on the money list. With only the top 125 players assured of retaining their tour privileges for next year, he needed a top-10 finish to secure his card. In his first 21 events, he had two top-10 showings. After a strong opening round, he felt a high finish was in his reach. He said he felt relaxed.

“I’ve never tried to make golf something more than it is,” he said.

Beljan did not think the high stakes of the moment caused his attack. His first go-round on the PGA Tour was only one of the challenges he had to confront this year. He married in the beginning of 2012, and in September, his wife, Merisa, gave birth to their first child, a boy. Beljan had his first panic attack a month before the birth of his son, passing out on an airplane that needed to make an emergency landing as a result.

He said he believed the stress of dealing with so many life-changing events in so few months caused his panic attack on the course.

“I don’t think it’s been the golf that’s done it at all,” he said. “I’ve had a lot of people try to diagnose me who have told me they’ve had the same problem, but I don’t think it’s the stress of the tour. It’s everything I’ve had going on this year.”