DALLAS, June 17 -- Doctors have a new set of medical tools to help identify seriously ill patients for whom transplants might safely be deferred.
Researchers described in today's American Heart Association journal Circulation a clinical model that accurately predicted survival among groups of patients with moderate to severe heart failure. "The new approach should facilitate more efficient use of scarce donor hearts and selection of high-risk patients for enrollment in clinical trials of new heart failure therapies," says Keith Aaronson, M.D. He is a leader of a research team at the Hospital of the University of Pennsylvania, Philadelphia, and Columbia University's College of Physicians and Surgeons in New York City.
Because of donor organ shortages, several hundred individuals die each year while awaiting transplants. In 1995 there were 746 such deaths.
The model is made up of seven readily measurements, none involving "invasive" steps such as putting a diagnostic tube inside the heart. "Our goal was to separate out those patients who will do well for a time," explains Aaronson.
The research team initially evaluated 80 clinical characteristics in 268 heart-failure patients (80 percent of them men) before selecting the seven criteria that proved most accurate. A score was calculated for each patient based on seven tests, which are commonly obtained in patients with heart abnormalities including measures of oxygen use during exercise, blood pressure and resting heart rate, says Aaronson, now medical director of the heart transplant program at the University of Michigan Medical Center, Ann Arbor.
Using the test results, the researchers arrived at a predictive "score" for each patient and identified threshold values at which risk changes significantly and classified patients into low-, medium- and high-risk groups. During follow-up, the 268 Pennsylvania patients were compared with 199 other transplant candidates at New York who served as a "validation" group. One-year survival in the two low-risk groups was 93 percent and 88 percent, respectively; 72 percent and 60 percent in the medium-risk groups, and 43 percent and 35 percent in the two groups considered at high risk for emergency heart transplant or death without a transplant.
"Transplantation can be safely deferred in the low-risk group," he says.
Media advisory: Dr. Aaronson can be reached in Ann Arbor at (313) 936-5265. Reporters may call (214) 706-1173 for copies of the reports. (Please do not publish telephone numbers.)