BOSTON – Patients with three or more risk factors who were listed with the highest urgency for a heart transplant—status 1A—on the U.S. waiting list had at least a 30% risk of dying before a donor heart was available, based on actual experience during 2000–2006.
Records from the United Network for Organ Sharing (UNOS) for this period showed that when high-risk patients (defined as those with more than three risk factors for death) received a mechanical circulatory support device, their 90-day survival rate jumped from 50% to 89%, said Dr. Katherine Lietz, who presented an analysis of UNOS data at the annual meeting of the International Society for Heart and Lung Transplantation. When a ventricular assist implant is used this way, it's often called a “bridge-to-transplant” device.
“To bridge or not to bridge is one of the most challenging decisions for medically managed, high-urgency, status 1A patients” who are awaiting a heart transplant, said Dr. Lietz, a transplant cardiologist at Columbia University in New York. Three key factors enter into this decision: the patient's risk for dying while awaiting a donor heart, the chances for successfully receiving a transplanted heart, and the risk of complications from implantation with a mechanical circulatory support device.
To better document the first two factors, Dr. Lietz and her associates analyzed data collected on 1,755 patients who were listed with UNOS as status 1A candidates for a heart transplant during January 2000-December 2006. During their first 30 days on the UNOS list, 14% of the patients died, 49% received a transplanted heart, 33% remained active on the list, and the remaining 4% were removed from the list because their status had improved.
The investigators identified the following six clinical or demographic features that were significantly associated with an elevated risk for death during the first 30 days on the list: blood type O, age older than 60 years, ventilator support, intra-aortic balloon pump, serum creatinine greater than 1.5 mg/dL, and serum albumin less than 3.0 g/dL.
Further analysis showed that the risk of death increased in patients who had higher numbers of these risk factors. Patients with none of these risk factors had an 11% risk of dying while they were maintained on medical treatment during their first 30 days on the list. Mortality risk rates increased as the number of risk factors rose (see box).
A second analysis identified a non-O blood type and a body weight of 89 kg or less as the most important determinants of receiving a heart transplant during the first 30 days on the list. Patients who met both of these criteria had a 66% chance of receiving a heart during this period. Those with either one of these two factors had about a 50% chance, and patients without either factor had about a 23% chance of receiving a donated heart, Dr. Lietz said.
She stressed that patients and their physicians need to determine how these findings can be used to help guide individual decisions about whether to rely on medical treatment alone or opt for implantation of a mechanical circulatory support device while a patient is listed and awaiting a heart. Dr. Lietz suggested that a reasonable cutoff might be a risk for dying of 30% or greater while listed, which corresponds to a patient's having three or more mortality risk factors.
The UNOS data showed that these patients stood to substantially boost their chances for survival if they received a mechanical circulatory support device.
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