Heart disease remains the nation's biggest killer, taking a life every 32 seconds, but researchers have made "unbelievable" progress in taming the disease, according to the American Heart Association.

Figures released Sunday show that deaths from heart and blood vessel disease have dropped 24 percent during the past decade. Researchers attribute the improvement to healthier living habits and better treatment."The public ought to appreciate the progress that has been made in heart disease over the past 20 years," said Dr. Myron L. Weisfeldt, the association's president-elect.

"It's almost unbelievable. There is almost no form of heart disease that we can't approach without meaningful treatment."

However, Weisfeldt, a heart specialist at Johns Hopkins University, cautioned that much work remains in improving care and encouraging people to take better care of themselves.

"I believe we can prevent at least 50 percent of the ischemic heart disease in the United States by the year 2000 if we stop smoking, get cholesterol treated if it's above 220 and identify and treat hypertension," he said.

Ischemic heart disease is the clogging of blood vessels that feed the heart. It underlies most heart attacks, the single most lethal heart ailment.

The association said that in 1986, the most recent year for which there are statistics, an estimated 978,500 Americans died from heart attacks, strokes and other diseases of the heart and blood vessels. Cancer, the No. 2 killer, took 466,000 lives.