From Medical Correspondent Rhonda Rowland

DALLAS (CNN) -- A drug that's been around for 30 years can save lives and prevent hospitalization in people with congestive heart failure, researchers announced Wednesday at the American Heart Association meeting in Dallas.

Research results were so dramatic that a related study was halted more than a year early.

The drug, Aldactone, reduced deaths by 27 percent when given in addition to standard therapy.

"So we think this is going to have a tremendous impact in the well-being of patients with heart failure," said Dr. Bertram Pitt of the University of Michigan. "Save them hospitalization, keep them alive, at least in this severe group of patients which is an important, tough group to treat."

Heart failure affects an estimated 5 million Americans.

Other new studies highlighted at the conference looked at the role of cholesterol-lowering drugs.

Researchers showed for the first time that heart attack and stroke can be reduced by boosting HDL - the good cholesterol - with a cholesterol drug called gemfibrozil.

One in four heart disease patients have normal 'bad' cholesterol levels, but low 'good' cholesterol levels.

"We found the patients on the gemfibrozil had a 22 percent lower risk of heart attack and coronary deaths," said Dr. Hanna Rubin of the VA Medical Center in Minneapolis. "They also had a 25 percent reduction in risk of stroke and a 60 percent reduction in minor strokes."

Another study found certain drugs can delay or prevent the need for surgery.

High doses of a type of cholesterol-lowering drugs called 'statins' were given to patients with mild to moderate angina, or chest pain. Usually, doctors recommend balloon angioplasty in these patients to open clogged arteries.

"Eighty-seven percent of the patients who took the drugs were able to avoid angioplasty over the 18 months of the study," Pitt said.

Patients with mild to moderate angina account for about one-fourth of the heart patients seen by doctors.