McCormack, king of sport, is critically ill after heart attack

Mark McCormack, the super agent whose client list reads like a roll-call of the world's sporting and artistic aristocracy, was last night critically ill after suffering a heart attack.

The 72-year-old impresario, whose company IMG (International Management Group) last year had revenues of $1.3bn (£900m), was surrounded by his family at an unnamed American hospital after falling ill earlier this week.

With a personal fortune of £600m made over more than 40 years, McCormack is regarded as the man who put commercialism into sport.

IMG, the world's largest sports and artists' management company, refused to reveal the circumstances of the heart attack or the state where he was being treated. His American home is in Florida. A spokeswoman for the company said: "Mr McCormack has been hospitalised following cardiac arrest. He had immediate medical attention and his condition has stabilised."

McCormack has been called the "most important man in sport" and the "godfather of golf". Having attended Yale Business School and played college golf, McCormack was just the man to help out Arnold Palmer with a few deals when the charismatic American golfer approached him in 1960.

They sealed their first contract with a handshake. Two years later Palmer's earnings had increased from $6,000 to $500,000 (£300,000). Tiger Woods, the world's best golfer, makes more than $60m (£37m) a year thanks to McCormack.

IMG, of which McCormack is founder, chairman and chief executive, operates in 33 countries and handles clients from all parts of the sporting and entertainment industry. The models Heidi Klum and Tyra Banks are on his books, as are the singers Placido Domingo and José Carreras and the physicist Stephen Hawking.

In tennis, IMG represents the Williams sisters, who dominate the women's game, while Andre Agassi, Pete Sampras, Martina Navratilova and Monica Seles have been clients. In golf, he has worked with Jack Nicklaus, Gary Player, Nick Faldo, Greg Norman and Colin Montgomerie.

McCormack would often set out to sign up a sport's iconic figures: Palmer in golf, Rod Laver in tennis, Jackie Stewart in motor racing, Jean-Claude Killy in skiing and Wayne Gretzky in ice hockey. Now he is investing in the stars of the future by running sporting academies.

In 1967, McCormack set up a television arm, Trans World International (TWI), which became the biggest producer of televised sport in the world.

From 1968, he has handled the television and marketing rights for Wimbledon, a role he now also provides for the Open Golf Championship.

McCormack's ideas went further than merely representing sportsmen and women. He promoted events and got TWI to televise them. In golf, he founded the World Match Play Championship at Wentworth in 1964 (first winner: Arnold Palmer). In 22 years of promoting official events on the European Tour, IMG has injected $92m (£57m) in prize money.

In 1986, McCormack married for the second time, to the tennis player Betsy Nagelsen. His three children from his first marriage all work at IMG.