Significant progress has been made in pediatric heart transplantation over the last 30 years, according to a new report from the Pediatric Heart Transplant Society Registry (PHTS) published in Pediatric Transplantation. The report also reveals areas for improvement, particularly in children with single ventricle anatomy, the most common form of congenital heart disease.
“Over the decades, both waitlist and post-transplant survival has been improving for children across all age groups,” says lead study author Marc E. Richmond, MD, director of Pediatric Advanced Cardiac Care and Transplantation at NewYork-Presbyterian and Columbia. “There have been such great strides in the surgical technique and the immediate postoperative care of these patients that we are seeing significantly improved outcomes. The biggest success has been improvement in the first year, post-transplant, particularly the first 30 or 60 days.”
There have been such great strides in the surgical technique and the immediate postoperative care of these patients that we are seeing significantly improved outcomes. The biggest success has been improvement in the first year, post-transplant, particularly the first 30 or 60 days.
— Dr. Marc Richmond
Specifically, the report highlights several improvements over the last 30 years:
- Waitlist survival at six-months increased from 72% to 84%
- One-year survival jumped from 67% to 80%
- Death attributed to both acute rejection of the organ and early graft failure (less than 30 days) decreased from 19% in the first decade of the registry to 9% in the most recent.
Less Favorable Outcomes
However, outcomes aren’t consistently positive, Dr. Richmond cautions. “The disappointing part is that over the long run, the survival rate has become stagnant,” he says. “The first couple of decades or so, there were some improvements in the long-term outcomes. Now most of the advancements in long-term outcomes are driven by short-term improvements. Our youngest patients with single ventricle anatomy, neonates who have not yet had surgery or have had one surgery, still have the lowest survival after being listed for transplant, despite all the advances we've made in their care otherwise.”
The lack of proper mechanical circulatory support in the smallest patients is a likely culprit. “Even among our non-congenital heart disease patients, our younger patients have worse waitlist mortality compared to older children and certainly teenagers and adults,” says Dr. Richmond. “We believe a big part of that is that the best ventricular assist devices (VADs) to help support patients to transplant are adult sized. We can push those down to a certain size, but below that, the pediatric sized devices we have are inferior.”
Equally important, none of the devices are designed for congenital heart disease. “Once you get younger patients with more complex anatomy and physiology, we just are not as successful at supporting them mechanically to transplant as we are with older patients,” says Dr. Richmond.
Progress, Decade by Decade
According to the report, the registry is characterized by three distinct eras The early era, 1993 to 2004, was the early phase of pediatric heart transplant as a discipline. The first successful pediatric heart transplant was performed at NewYork-Presbyterian in 1984. “By 1993, enough centers had done transplants that it was the tipping point to gather data collaboratively,” says Dr. Richmond. “No one had much experience yet, and we were all learning together.”
The middle era of data, 2005 to 2009, reflected a greater understanding of the long-term effects of heart transplantation on children. “For example, when they did the first transplant, nobody knew whether the heart would grow with the child or not. It does,” says Dr. Richmond. “In that middle era, it was a more mature field. We were getting better outcomes and starting to offer transplant to to more patients.”
The recent era of the PHTS registry, 2010 to 2019, has been marked by new therapeutics and other advances. “There's been a lot of pushing the envelope and a shift towards using transplant to help patients with failed congenital heart disease palliation, which are a higher risk group,” Dr. Richmond says. “Expanding access to transplant for that higher risk group has been a hallmark of the most recent era.”
The PHTS Registry’s Unique Benefits
The PHTS Registry was founded as a collaborative effort among providers of the life-saving medical care and surgery for children with end stage heart failure. Since 1993, 11,995 children have been listed for a heart transplant in the registry, with 9,755 listed during the study period.
Although there are other transplant registries, either for all organs or for adult transplant, the PHTS registry is the only one that is specifically designed for pediatric heart transplant. “That has allowed us to home in on some unique aspects in children, particularly congenital heart disease, and to put those data out there to help others understand how transplant can be used for this high-risk group of patients,” says Dr. Richmond.
“Many cardiologists and others in medicine have an older view of how well children can do after transplant and see it as a last-ditch effort and a not very successful therapy,” he continues. “I hope this will stand as a benchmark for understanding that transplant can be very successful, even for our highest risk patients, the single-ventricle patients.”
There have been such great strides in the surgical technique and the immediate postoperative care of these patients that we are seeing significantly improved outcomes. The biggest success has been improvement in the first year, post-transplant, particularly the first 30 or 60 days.
— Dr. Marc Richmond
So far, the registry’s data have yielded 125 publications. Dr. Richmond hopes this publication will generate new study questions aimed at addressing ways to improve the transplantation process.
A Transplant Powerhouse
A pioneer in pediatric heart transplant, NewYork-Presbyterian continues to be a leading player in the field. “Historically we have been the largest pediatric heart transplant center in the country,” says Dr. Richmond. The hospital has more than 600 pediatric heart transplants recorded in the United Network for Organ Sharing (UNOS), which administers organ allocation for transplantation in the U.S., and additional patients that were transplanted before UNOS was founded.
“Having a large volume program allows us to gain a lot of experience in many areas and to expand access and take risks on patients that smaller programs are unable to,” Dr. Richmond says. “That's allowed us to push the boundaries and help many patients who otherwise may not have been afforded the chance at transplant.”
This report offers the opportunity to reflect on the advancement of heart transplants in the smallest humans. “We can see how every year things get a little bit better for our patients,” says Dr. Richmond. “When I counsel patients and families today, I tell them, ‘I know you'll do at least this well, but probably even better because the numbers keep improving.’ We just keep advancing the science and our understanding of how we manage and surveille these patients for rejection and other complications.”
