Cheney, 69, who has remained a forceful advocate for the former Bush administration and a leading Republican figure since leaving office last year, has a history of heart trouble. He was admitted to George Washington University Hospital in Washington on Monday after experiencing chest pains.

Lab tests revealed evidence of a mild heart attack, Cheney aide Peter Long said in a statement. Long reported that Cheney is ``feeling good'' after undergoing a stress test and a heart catheterization. The latter procedure examines blood flow to the heart and tests how well the heart is pumping.

A heart attack occurs when blood flow to the heart muscle is blocked. The statement from Cheney's office did not say whether he needed to have an angioplasty, a procedure to clear a blockage.

The heart attack is Cheney's fifth since age 37.

Cheney had bypass surgery in 1988, as well as two later angioplasties to clear narrowed coronary arteries, and bypasses tend to last about a decade before the rerouted blood vessels start to clog.

In 2001, he had a special pacemaker implanted in his chest. In addition, doctors in 2008 restored a normal rhythm to his heart with an electric shock. It was the second time in less than a year that Cheney had experienced and been treated for an atrial fibrillation, an abnormal rhythm involving the upper chambers of the heart.

The former vice president has kept a high profile since leaving the White House. He has sparred with the Obama administration over plans to close the U.S. detention facility for terror suspects at Guantanamo Bay, Cuba, and hold the trials of several high-profile detainees in civilian courts rather than military tribunals.

He made a surprise appearance last week at the Conservative Political Action Conference, where he accompanied his daughter Liz. He was greeted with chants of ``Run, Dick, Run,'' but said ``I am not going to do it.''

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