At first, Kathy Kastan's symptoms just seemed weird. An avid athlete, she would get oddly tired, struggle to catch her breath, and wince at the pain in her shoulder and back when she exercised. She tried shaking it off, but the problems kept nagging her, so the 41-year-old consulted a cardiologist.

"He said, 'You're healthy as a horse. I never want to see you again,' " said Kastan, who lives in Cordova, Tenn.

"I was one of the lucky ones. I escaped an actual heart attack," said Kathy Kastan, 41, of her initially misdiagnosed heart disease. (Troy Glasgow For The Washington Post) _____The Heart_____ � United Therapeutics Reports Profit (The Washington Post, Aug 4, 2004) � The Fairfax Safety Net (The Washington Post, Aug 3, 2004) � Frozen to Life (The Washington Post, Aug 3, 2004) � 1 + 1 = ?#!@?! (The Washington Post, Aug 3, 2004) � No-Stigma ID (The Washington Post, Jul 20, 2004) � More Heart News _____Free E-mail Newsletters_____ � Lean Plate Club

But she got worse -- so bad that crushing chest pain knocked her down every time she tried to work out. Finally, she went to specialists who discovered that Kastan did have serious heart disease -- just not the familiar, clogged-up-artery kind. Instead, her arteries would mysteriously spasm, strangling the blood flow to her heart muscle.

"It's amazing how many women have been through this. They have these symptoms, and nobody can figure out what's wrong," she said. "I was one of the lucky ones. I escaped an actual heart attack."

Doctors are starting to realize that many women probably have Kastan's kind of heart disease, as well as other forms that differ in essential ways from the well-known pattern that strikes most men. This new understanding -- that heart disease may be a fundamentally different disease in many women -- has far-reaching implications for medicine's ability to defend women against the nation's No. 1 killer. Contrary to persistent misconceptions, heart disease claims the lives of more women than men.

"The whole disease is poorly understood in women, from the expression of the symptoms all the way down to some of the basic mechanisms," said Carl J. Pepine, a cardiologist at University of Florida's College of Medicine in Gainesville. "The disease has a very broad spectrum, and more men are at one side and more women are at the other side."