MONDAY, May 9 (HealthDay News) -- Hospitals that perform a large number of heart transplants are the best places for older, sicker patients to receive a new heart, according to new research.

In the study, Johns Hopkins researchers analyzed data from all 17,211 heart transplants done in the United States between January 2000 and December 2009. The investigators also ranked the hospitals where the transplants were performed as low-, medium- or high-volume centers.

Hospitals that performed fewer than six heart transplants a year were ranked as low-volume centers, and those that did more than 15 a year were deemed high-volume centers. During the study period, 5.4 percent of the transplants were performed at low-volume centers and more than 67 percent were done at high-volume centers, the study authors found.

Among high-risk patients, the risk of death within a year after transplant was 67 percent higher in those who had their heart transplant at a low-volume center compared to those who received a new heart at a high-volume center, the research showed.

The findings suggest that high-risk patients should receive heart transplants only at high-volume centers, the researchers said.

The study was scheduled for presentation Monday at the American Association for Thoracic Surgery annual meeting in Philadelphia.

"There's growing evidence throughout medicine and surgery that the volume of cases done at a given medical center has an impact on outcomes," study leader Dr. George J. Arnaoutakis, a general surgery resident at the Johns Hopkins University School of Medicine, said in a Hopkins news release. "Transplant teams more familiar with a procedure do a better job than those that only do a handful each year."

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

The U.S. National Heart, Lung, and Blood Institute has more about heart transplant.