The gap in survival rates for heart transplant recipients who receive preimplantation ventricular assist devices (VADs) and those who do not receive such devices has narrowed since 2004, new research suggests.
Data presented here at American Transplant Congress 2009: The Joint Annual Meeting of the American Society of Transplant Surgeons and the American Society of Transplantation show that following the initial 6-month posttransplant period, when survival is about 5% greater in VAD patients, this gap narrows over time.
"VADs have a significant role for some patients awaiting heart transplants," said Douglas Horstmanshof, MD, codirector, INTEGRIS Nazhi Zhudi Transplant Institute in Oklahoma City, Oklahoma.
"They have the potential of decreasing the mortality on the waiting list and improving the physiological status of the patient prior to transplantation but may have an adverse effect on the posttransplant morbidity and mortality," he added.
Dr. Horstmanshof and colleagues conducted a review of heart transplants from the Organ Procurement and Transplantation Network/United Network for Organ Sharing database from January 1, 1999, to December 31, 2007. A total of 16,356 heart transplants were identified. Among these, 3390 patients were classified in the pretransplant VAD group and 12,966 in the NVAD [nonvascular assist device] group. The investigators did a retrospective analysis of posttransplant survival at 6 months and 1 and 3 years for each group.
"If we look at earlier databases, specifically the [International Society for Heart & Lung Transplantation] reports, we see that we have seen a detriment in survival in patients who undergo heart transplant after undergoing VAD," Dr. Horstmanshof told conference delegates. However, analysis of the United Network for Organ Sharing database shows that since mid-2003, patient survival in VAD recipients posttransplantation is more closely mirroring the NVAD population.
"Patient survival in the VAD group overall is inferior to that of the NVAD group posttransplant. However, the difference is about 5% and appears early in those first 6 months, and then patients have similar mortality over time," he said.
Sickest Patients Receive VAD
The investigators determined that overall patient survival rates of the VAD group were significantly lower than those of the NVAD group (86.7% at 6 months, 83.8% at 1 year, and 76.7% at 3 years for VAD vs 90.9% at 6 months, 88.1% at 1 year, and 80.8% at 3 years for NVAD; log-rank P < .001). "The difference is consistently about 4% to 5% between the 2 groups," said Dr. Horstmanshof.
However, the difference in 1-year patient survival rates between the 2 groups has narrowed since 2004. "There is still a gap between VAD and NVAD recipients," said Dr. Horstmanshof. "But the good news is that patients in the modern era (defined as halfway through 2003 onward) have almost superimposable survivals in terms of VAD vs NVAD posttransplant after the initial 6 months. You can clearly see a significant difference from 1999 through [the first half of] 2003."
The researchers also determined the survival for patient receiving a left VAD (LVAD) alone was identical to the NVAD group at 3 years.
"The main finding for me is the identification that we don't want to wait until patients are too sick," Dr. Horstmanshof told Medscape Transplantation. "With the combination of better technology, multidisciplinary care teams that are doing better jobs caring for the patients pre- and postdevice, and better patient selection over the last several years, we're now able to see these improvements as a result."
However, VAD recipients are still at significantly higher risks for comorbidities posttransplant. These include much higher rates of dialysis, stroke, reoperation, antirejection therapy, and longer hospital stays.
"We don't know exactly why the patients had those comorbidities after transplantation," said Dr. Horstmanshof. "Theoretically, though, it is probably more patient-related issues than the VAD itself."
The investigators noted that 80% of the VAD recipients reviewed were classified as Interagency Registry for Mechanically Assisted Circulatory Support profile 1 or 2. "The point is that the patients who are receiving VADs today are the sickest, sometimes with a life span measured in hours. They are already having significant dysfunction and at increased risk for all kinds of morbidities," said Dr. Horstmanshof.
The investigators conclude that better patient selection, care, and probably also improved technology explain why the survival curves for VAD vs NVAD recipients seem to be coming together after the initial 6-month difference.
Weighing Risk/Benefit
"I think the data presented by Dr. Horstmanshof are important," said Maryl R. Johnson, MD, from the University of Wisconsin, Madison, who comoderated the session in which the data were presented.
"This is the largest series of data that I know of that shows equivalent survival in patients with VADs versus those not on VADs who receive heart transplants in the recent era," she said.
She agreed that VADs represent a useful option for those waiting for heart transplantation. "As VAD outcomes have improved, clinicians have become more willing to use VADs prior to the onset of severe multisystem organ dysfunction, which likely has also contributed to the improved outcome for all recipients of VADs," said Dr. Johnson. "The difficulty is in defining the point when the benefit of implanting a VAD outweighs the risk — which is a moving target as VAD outcomes improve."
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