Men who smoke and are high risks for heart attacks can, in effect, be "nagged" into stopping smoking and significantly reduce chances of heart attacks and other smoking-related diseases, according to an ongoing 10-year study.

The program, funded by the National Heart, Lung, and Blood Institute, resulted in one of the most dramatic reductions in cigarette smoking -- and better chance for health -- yet achieved by any large study group. The experiment, which was conducted in the mid-1970s, involved 3,795 smokers at 22 medical centers.

The average "stop smoking" program gets between 25 to 50 percent of a group to quit. After a year, a discouraging 75 percent may have relit.

By contrast, 40 to 45 percent of the 3,795 habitual smokers in the NHLBI program had quit after four years, most in the first year, and had not restarted. This greatly reduces the danger of heart disease, lung cancer and other illnesses.

The institute's stop-smoking program primarily consists of a steady barrage of antismoking education, counciling, hypnosis, weekend retreats, mutual support groups and other methods such as giving quitters "I.Q.," or "I quit," buttons and other encouragement.

"There is no one uniquely successful method," said Dr. Oglesby Paul of Harvard Medical School, one of the centers. "It seems that a combination of methods is what works."

This approach was only part of an overall health program, the largest trial ever of measures to prevent heart disease.

The first four years' results of this "Mr. Fit" trial were reported at the American Heart Association conference here.

In all, 12,866 men have participated. They were divided into an intensive study group and a control group of about 6,400 each, of whom 59 percent were smokers. The 3,795 in the stop-smoking program were the smokers in the intensive study group.

That group succeeded in reducing blood pressure, weight, smoking and the amount of cholesterol in their bloodstreams so that they cut their risk of a fatal heart attack by 25 percent compared to the control group, according to Dr. Paul and Dr. James Schoenberger of Rush-Presbyterian-St. Luke's Medical Center, Chicago, Paul chairs the trial's steering committee. Schoenberger is president of the heart association and a principal investigator.

The actual payoff -- the number of men who have had heart attacks by the time the study is done early next year -- will not be known before the fall of 1982.

"Mr. Fit" also stands for "MRFIT," or "multiple risk factor intervention trial." Volunteers between ages 35 and 57 were signed up in New York, Philadelphia, Boston, Baltimore, Chicago, Los Angeles, San Francisco and other cities.

All were men considered a "high risk" for heart disease because they had at least one and usually two of three "risk factors": high blood cholesterol, high blood pressure and the cigarette habit.

The volunteers were randomly assigned to either an "SI," or special intervention," group, or a "UC," or "usual care," group.

The usual care group has been given only an initial physical, an annual checkup for risk factors and recommendations to "see your own doctor."

The special intervention group has also had health lecturers, special tests -- like a carbon monoxide test to show them the dire effect of smoking on blood -- and follow-up sessions every two to four months. At times, some have had almost daily calls from a health counselor.

In the program's first four years:

Forty-five percent of the SI group, by their own account (40 percent by a stringent blood test), quit smoking, compared with 24 (and 23) percent of the UC group.

The SIs lowered average blood cholesterol by 19 points (from 254 to 235) compared with a 10-point drop in the UCs.

The SIs (many on diets or drugs to control blood pressure) lowered average diastolic pressure from 92 to 82, compared with a drop from 92 to 86 in the UCs.

The SIs lowered average weight from 189 to 185, compared with virtually no average loss among the UCs.