Beta Power

Hope after heart attacks

Of the 350,000 Americans each year who survive a heart attack, about 10% will die within a year, often from a second attack. But last week heart patients had cause for encouragement. The National Heart, Lung and Blood Institute announced that it was calling an early halt to a large-scale study because the drug being tested was so successful in reducing deaths in heart attack victims. Says NHLBl's associate director, Dr. William Friedewald: "The regular use of propranolol has the potential for saving at least 6,500 lives in the United States alone each year."

The curtailed study began in 1978 and involved almost 4,000 men and women, ages 30 to 69, who had suffered at least one heart attack. Half were given propranolol daily for two years; the rest, similar to the medicated group in sex, age, smoking habits and general medical condition, received placebos. Treatment was started within five to 21 days of the attack. Though the experiment was scheduled to run until June of next year, researchers cut it short when they discovered there were 26% fewer deaths in patients who had taken the drug for at least one year.

Propranolol belongs to a class of drugs known as beta blockers that gained widespread use in the 1970s. The drugs block nerve impulses to special sites (beta receptors) in body tissues. They reduce the rate at which the heart beats and the force of its contractions, thus decreasing its work load. More than a dozen beta blockers are in use worldwide, primarily for treatment of severe chest pain (angina), high blood pressure and arrhythmias.

Propranolol, the first beta blocker introduced in the U.S., is also the nation's second most widely prescribed drug (after the antiulcer drug Tagamet). Ayerst Laboratories, which manufactures propranolol under the name Inderal, plans to ask the Food and Drug Administration to approve its use as a post-heart attack treatment. As it is, physicians are free to prescribe it since it is already approved for other uses. Many heart attack patients are taking Inderal for other heart-related conditions. The FDA is also expected to rule favorably soon on Merck Sharp & Dohme's application to introduce another beta blocker, timolol, into the U.S. for use after heart attacks.

Propranolol's side effects are comparatively mild. Researchers caution that they do not know how long its protective effects last and when it should be discontinued. Even so, says Friedewald, the new test results represent an "exciting breakthrough."

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