New York Mayor Michael Bloomberg frequently talks about health — but never publicly revealed that he had heart surgery before running for mayor, a fact that emerged this week amid increased attention about his possible presidential aspirations.

The billionaire media mogul, who furthered speculation about his presidential ambitions last week when he declared himself an independent, did not disclose the surgery in 2000; he had two coronary arterial stents inserted to relieve a blockage in his heart. The operation was first reported by Newsweek this week and confirmed Thursday by Bloomberg's spokesman, Stu Loeser.

Bloomberg, 65, is now said to be in excellent shape. He has long been interested in public health, pushing for citywide bans on trans fats and smoking and donating millions of dollars to medical research and health causes. Before his election in 2001, Bloomberg was chairman of the board at Johns Hopkins University, his alma mater, where the school of public health bears his name.

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But Bloomberg never mentioned his heart trouble. He has said he takes an aspirin each day, often notes that he smoked long ago and frequently jokes about watching his waistline.

He was not yet a declared mayoral candidate for the 2001 campaign when he underwent the procedure. Loeser said Bloomberg had the operation because he had been experiencing fatigue and mild discomfort in his chest, and was up and about the next day.

Bloomberg's father had rheumatic fever as a child, which weakened his heart. He died when Bloomberg was in college.

Bloomberg would have revealed the surgery during his first campaign but was never asked, and he has not brought it up since then because he is private about his health, according to a person close to the mayor and familiar with his health.

Bloomberg denies any interest in running for president, but he has increasingly been traveling outside New York and speaking out on national issues, including health care.