Children awaiting heart transplant survive longer with VADs than ECMO

Ventricular assist devices (VADs) foster improved survival for children awaiting heart transplantation when compared to the current standard of extracorporeal membrane oxygenation (ECMO), according to a new study in the Journal of the American College of Cardiology.

When 164 pediatric patients were matched one-to-one to eliminate differences in baseline characteristics, those treated with VADs alone were twice as likely to survive from waitlist to transplant and survived an average of 39 percent longer versus patients treated with ECMO alone. A 90-day reduction in pre-transplant mortality was also observed in the VAD group (39 percent) versus the ECMO group (45 percent).

The study analyzed the survival rates to transplantation. No significant differences were detected in survival post-transplant.

“The use of TCS (temporary circulatory support) devices in children as a bridge to transplant has risen rapidly in recent years, led by the growth of magnetically levitated centrifugal flow pumps. Compared with conventional ECMO, TCS durations are longer, and more importantly, patient survival is superior,” wrote Vamsi V. Yarlagadda, MD, with the division of pediatrics cardiology at Stanford University, and colleagues. The authors said their study is the first to demonstrate improved survival for VADs over ECMO in pediatric patients.

Using Organ Procurement and Transplantation Network (OPTN) data, the researchers considered all U.S. patients 21 years old or younger who were supported with ECMO or TCS devices while on the waitlist for a heart transplant from 2011 to 2015. The number of TCS devices implanted in children increased from three or fewer each year before 2011 to 50 in 2015.

“With 50 implants in 2015 alone, TCS VADs now represent more than one of four VADs being implanted in U.S. children today, with no signs yet the growth has started to level off,” the researchers wrote. “This growth may be driven in part by disappointment with ECMO for short-term support as well as durable VADs in the smallest children, and by the encouraging early experience with TCS device support.”

The CentriMag-PediMag system (Abbott, Abbott Park, Illinois) was used in 65 percent of the 93 patients who received a TCS device over the study period. It also supported patients for the longest period, an average of 24 days versus six days for ECMO. The average support duration of all TCS devices combined was 19 days.

“Our findings suggest that select TCS devices—most notably the CentriMag-PediMag system—have made significant inroads not just as short-term circulatory support devices but also as long-term circulatory support devices in clinical situations where existing (Food and Drug Administration–approved) long-term devices have mixed results,” Yarlagadda et al. wrote.

For example, a previous study showed fewer than 10 percent of children weighing less than 10 kilograms with single-ventricle heart disease survived to transplant using currently available durable VADs. This group of small children “may stand to benefit the most from repurposing short-term devices to serve as long-term devices as a bridge to transplant,” Yarlagadda and colleagues wrote.

The researchers noted they couldn’t evaluate TCS devices against one another because there weren’t enough patients on each device for a propensity-score matched comparison. Also, they didn’t have data on device-related adverse events.

In an accompanying editorial, a pair of doctors from the University of Alberta, Edmonton, Canada, said the latter limitation could be addressed with analysis from an ongoing registry.

“As with any emerging therapy, defining criteria for optimal patient selection poses a significant challenge,” wrote Jennifer Conway, MD, and Sabin J. Bozso, MD. “The lack of clear safety outcomes remains the largest barrier to expansion of the use of short-term VAD support in the pediatric population. The PEDIMACS (Pediatric Interagency Registry for Mechanical Circulatory Support) registry collects data on short-term VADs including survival and adverse events. Emerging analysis from the PEDIMACS registry will help to better elucidate factors that may influence survival along with incidence of adverse events during short-term VAD support to develop optimal patient selection criteria.”