Risks seen in opposite-sex heart transplants

Surgeons perform a procedure in a file photo.

WASHINGTON (Reuters) - Men and women who get heart transplants are more likely to die when the donor was of the opposite sex, U.S. researchers said on Wednesday.

The cause is not clear but could be due to size differences in the heart -- men's tend to be larger -- or certain hormonal and immunological factors, according to researchers from Johns Hopkins University in Baltimore.

Patients who got a heart transplant from a donor of the opposite sex had a 15 percent higher risk of death compared to those whose donor was the same sex, they told an American Heart Association meeting in New Orleans.

The findings were based on data from the United Network of Organ Sharing, which administers the U.S. organ donation system, on 18,240 people who got a heart transplant from 1998 to 2007.

The lowest survival rate was in men who got a donor heart from a woman, they said.

Men given a heart from a female donor also were more likely to experience organ rejection. Women getting a male donor heart were no more likely to have organ rejection than if the heart came from another woman.

The findings indicate that if a choice is available, doctors should give a transplant patient a heart from a donor of the same sex, the researchers said.

If that is not possible because of the limited availability of donor hearts, patients should go ahead and get a transplant from the opposite sex donor because any transplant if far better than heart failure, they added.

"One of the messages that we don't want to give is that people should be waiting for a same-sex transplant, because the rate of survival is clearly superior having a transplant to not having a transplant whether you get your transplant from the same sex or the opposite sex," said Dr. Eric Weiss of Johns Hopkins, one of the researchers.

There are not enough donor hearts for every person who needs one and many people die while awaiting a transplant.

"I would hesitate to have patients think that somehow, because they get a transplant from the opposite sex, that it condemns them to death," Weiss said in a telephone interview.

More than 2,000 heart transplants are performed in the United States each year, with men making up about three quarters of the patients, according to the American Heart Association.

The five-year survival rate after a heart transplant is 72 percent for men and 68 percent for women.

In the surgery, doctors remove a damaged or diseased heart and replace it with a healthy one from a dead donor. The first heart transplant was performed in 1967.

(Editing by Julie Steenhuysen and John O'Callaghan)