The number of American women who died from heart disease dropped in 2004, continuing a trend seen since 2000, government researchers said Friday.

A report released by the National Institutes of Health (NIH) showed that heart disease deaths in women declined by nearly 17,000 between 2003 and 2004, the last year statistics were available.

Experts were quick to warn that the decline in death reflects mostly improvements in treatment and not a large drop in new cases of heart disease among women.

At the same time, rising obesity rates and other worrisome health trends threaten to undo recent progress against heart disease, they said.

More than 654,000 Americans died from coronary heart disease in 2004, making it the leading cause of death in both women and men.

In 2003, 7,017 of every 100,000 women over 45 died from the disease, according to the CDC.

Heart Disease Awareness Rising

More women are aware that heart disease is the leading killer of women -- 55 percent knew this in 2005 vs. 34 percent in 2000, the NIH says.

“Many good things are going on,” says Paul Sorlie, PhD, head of the National Heart, Lung, and Blood Institute's (NHLBI) epidemiology branch.

“Our goal continues to be achieving even greater awareness and contributing to the trend of steady decline in deaths," says Elizabeth G. Nabel, MD, director of NHLBI.

Improvements in Treatment and Technology

The primary driver for the drop in deaths appears to be improved drug treatment and diagnostic technology in hospitals.

The chance that a middle-aged woman suffering a heart attack or heart failure will die in the hospital has dropped more than 75 percent since 1980, Sorlie says.

At the same time, wider use of drugs that lower blood pressure and cholesterol are also credited with preventing a growing number of deaths.

Sorlie also points out that rates of smoking -- a key risk factor for heart disease -- have dropped by almost half among women over the last four decades.

“This is a very significant factor,” he says.

Obesity Threatens Improvements

However, there are ominous signs obesity could undermine the positive trends in Friday’s report.

About one-third of U.S. women are obese, giving them a prime risk factor for heart disease.

At the same time, a major federal health survey encompassing 1999 to 2004 showed a 29 percent rate for adult hypertension, up from 23 percent a decade before.

That is creating concern that obesity and hypertension, both major heart disease risk factors, could soon undo the improvements seen in the last few years.

“Those are going to start to have consequences,” Sorlie says.

"Chronic disease takes time to get bad. And as obesity is in people for longer periods of time, it will affect their blood pressure, cholesterol, and other things,” he says.

“I think people are very concerned that this very nice decline we’ve seen -- and everyone's very pleased -- may not continue,” Sorlie says.

By Todd Zwillich, reviewed by Louise Chang, MD

SOURCES: National Heart, Lung and Blood Institute. National Center for Health Statistics. Paul Sorlie, PhD, chief, epidemiology branch, NHLBI. CDC: "Health, United States, 2006." American Lung Association: "Trends in Tobacco Use." National Center for Health Statistics: "National Health and Nutrition Examination Survey III."