The Department of Health and Human Services, releasing a study on recent strides in human heart transplantation, has deferred a decision on whether Medicare will start paying for heart transplants for its patients.

HHS Secretary Margaret M. Heckler said she needed time to study the report by the Batelle Human Affairs Research Centers of Seattle about the costs and availability of donor hearts before making her decision. She said that most of the recipients of Medicare are elderly or disabled and might not be suitable for transplants under current medical standards.

Doctors normally require that heart recipients be vigorous, have no complicating conditions and a good chance of surviving, and be no older than 55.

The study found that if Medicare revised its rules and agreed to pay for transplants, only 29 patients would be likely to receive them this year, although the number could rise to 42 by 1989. The cost would be $2 million a year initially, rising to $3.4 million by 1989.

Heckler said the study shows that there have been "dramatic" developments in heart transplants in recent years.

More than 80 percent of 441 recipients studied were alive after one year and more than 50 percent after five.