Survival much lower if transplanted fewer than four weeks after heart pump insertion
The timing of a heart transplant after a person receives a heart pump can make the difference between life and death. Cardiac surgeons at the University of Maryland Medical Center have found a clear relationship between the duration of heart pump support in heart failure patients implanted with a ventricular assist device and the risk of death following a transplant. They conclude that survival rates are best if the transplant occurs no earlier than one-to-three months after implantation of the assist device. The results of the study will be presented May 5, 2003, at the annual conference of the American Association of Thoracic Surgery in Boston.
"One of the questions we face as physicians is when we should transplant a patient after they've received a ventricular assist device," says James S. Gammie, M.D., a cardiac surgeon at the University of Maryland Medical Center and assistant professor of surgery at the University of Maryland School of Medicine. "The timing is a challenge," says Dr. Gammie, "because the physician must weigh the impact of several factors, including the availability of donor hearts, the chance of device-related complications and the physical condition of the recipient." Dr. Gammie is the principal investigator of the study.
Ventricular assist devices, or heart pumps, are typically implanted in people with end-stage heart failure whose hearts cannot circulate enough blood. Impaired blood flow may damage the kidneys, liver and other organs and cause fluid retention and difficulty breathing. Many patients at this stage are so sick that they are placed on the waiting list for a heart transplant. Ventricular assist devices can improve the heart's pumping function and are often used as a "bridge to transplant," to keep the patient alive until a transplant becomes available.
"The devices are not risk free," Dr. Gammie says. "The longer a patient has the device, the more likely he or she is to have a stroke, an infection or failure of the device. But our study suggests that transplanting too soon after a pump goes in could increase the risk of death, because most patients who qualify for a heart pump are already weak and in major distress."
The researchers examined data from the United Network for Organ Sharing (UNOS), the organization that develops organ transplantation policy in the United States and facilitates the organ matching and placement process. The study focused on 2,692 adult heart transplants performed in the United States between October 1999 and March 2001. Seventeen percent, or 466 out of the 2,692 transplant recipients had received a ventricular assist device.
"During the period of our study," says Dr. Gammie, "UNOS rules called for a patient to be placed at high priority status for a transplant during the first month after a pump was put in. After that, the patient would drop to a lower priority status. So there was some pressure to get them transplanted within the first 30 days. If a donor heart became available the next day, or the next week, you might put it in."
Dr. Gammie says the UNOS policy has changed recently, and the study findings support that change. "Now, that one month window of highest priority can start anytime, so we can wait a month, or six weeks, after the patient has recovered, before we decide to bump him or her up to the top status to help get his heart transplant," says Dr. Gammie.
One-year survival of the 2,692 patients undergoing cardiac transplantation during the study was 84.7 percent. As a group, patients bridged to transplant with a ventricular assist device had a slightly lower one-year survival rate (79.7 percent) compared to patients without a pump. The one-year survival rate was at least 10 percent lower for patients transplanted less than two weeks or more than six months from device implantation.
The researchers also found that there was clear improvement in both kidney and liver function with heart pump support over several weeks. "As patients start to rehabilitate," says Dr. Gammie, "they get up, they start to walk around, they're exercising, and their kidneys and liver begin to work well."
The research team also included Bartley P. Griffith, M.D., and Richard N. Pierson III, M.D., of the Division of Cardiac Surgery at the University of Maryland Medical Center, Leah B. Edwards, Ph.D., at the United Network for Organ Sharing, Richmond, VA, and Lana Tsao, M.D., from the Division of Cardiology, Beth Israel Deaconess Medical Center / Harvard Medical School, Boston, MA.
###Founded in 1917, the American Association for Thoracic Surgery (AATS) is dedicated to excellence in research, education and innovation in thoracic surgery. Established by some of the earliest pioneers in the field of thoracic surgery, the AATS has grown to an international organization of more than 1100 of the world's foremost cardiothoracic surgeons representing 29 countries. More than 2,500 medical professionals are expected to participate in the AATS 83rd Annual Meeting, May 4-7 in Boston, MA, where more than 100 scientific papers will be presented. The AATS publishes the highly regarded, peer-reviewed Journal of Thoracic and Cardiovascular Surgery, the official journal of the Association.
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