Does Center Volume Impact VAD Implant Outcomes in Children?

A new study from Cleveland Clinic Children’s sheds light on the relationship between pediatric center volume and ventricular assist device (VAD) outcomes.

Results from a large database study show that fewer patients experience pre-implant complications, including intubation, sedation and pre-implant paralysis, at centers performing a higher volume of VADs. This finding suggests proactive interventions and other strategies may be more utilized at higher volume centers. Of note, center volume did not appear to impact post-implant mortality.

The authors also identified themes in clinical management in high-volume VAD centers, including more utilization of an implantable continuous device and using a VAD as a “bridge to decision.”

They published their findings in The Journal of Heart and Lung Transplantation.

Addressing a gap in the research

Shahnawaz Amdani, MD, Section Head of Pediatric Heart Function and Transplant at Cleveland Clinic, says the concept of the volume-outcomes relationship is not new to the surgical literature. Over the past several decades, many studies have shown that outcomes tend to be better at centers with higher volumes.

However, there was a gap in the literature when it came to the pediatric VAD volumes-outcomes relationship, “There were no pediatric studies to date that explored the relationship between center volume and its impact on morbidity and mortality post-VAD implant,” he notes.

This is, partly, because VAD implantation in children is a relatively recent innovation. The technology became available in the early 2000s, and the Berlin heart received FDA approval in 2012. Since then, Dr. Amdani says, there’s been a steady uptick in VAD use.

Prior to this study, the STS-Pedimacs database, the national prospective registry comprising pediatric VAD data, celebrated its 1,000^th VAD implant in children with advanced heart failure. They’ve been systemically capturing this data since 2012, making it an ideal data set for this type of analysis. It includes a range of variables, from demographic and clinical characteristics to outcomes data.

The STS-Pedimacs data reflect technically challenging cases: pediatric patients present with smaller, more challenging anatomy and often unique congenital abnormalities. Dr. Amdani and team surmised it would be a meaningful investigation to better understand the specific needs of this patient population.

Designing the study and defining center volume

The team analyzed patient electronic health records from children (age < 19) undergoing initial left VAD (LVAD) implantation across 44 pediatric centers from 2012 to 2020. Based on the center’s patient volume, it fell into one of three categories, as standardly defined by STS-Pediamacs: low (1-15 implants) medium (15-30) and high volume (> 30).

The team found that 782 children received an LVAD implant during the study period. The analysis also revealed that of the 44 centers, 16 (36.4%) were low, 11 (25%) were medium and 17 (38.6%) were high volume.

Common approaches at high-volume centers

The authors reported a few common practice differences among the centers, including the following:

A more proactive intervention. Children undergoing implantation at a high-volume center were less likely to be intubated, sedated, paralyzed or non-ambulatory pre-implant than those at a lower-volume centers.

Elaborating on this, Dr. Amdani says, “One thing that became obvious while looking at the data is that higher-volume programs were more likely to use a proactive approach to VAD implantation.”

“These are very sick patients. Often, they have advanced heart failure, congenital heart disease and multiple comorbidities. So, time is of the essence. And one of the things we’ve noticed is that higher-volume programs tend to intervene and rescue patients earlier.”

Use of implantable continuous device.Patients at a high-volume LVAD center were more likely to receive an implantable continuous device rather than paracorporeal pulsatile devices. The implantable devices represent “the latest generation [of the device],” according to Dr. Amdani.

While there are no comparative outcomes data of the two different devices, recent reports have indicated a survival benefit of using the implantable continuous device as a bridge.

VAD as a bridge to decision. High-volume VAD programs also appeared to be more likely to use a VAD as a bridge to decision, recovery or as a rescue therapy.

“This reflects an attempt by higher volume VAD centers to try and salvage children with advanced heart failure and complex congenital heart disease. It may be that higher volume VAD centers are more likely to attempt to save sicker children, who may not have a similar opportunity at lower volume programs,” says Dr. Amdani. Often, such children can be successfully resuscitated with a VAD and, ultimately, become transplant candidates if their end-organ dysfunction reverses.

Managing outcomes and complications

Unlike in adults, there was no relationship between a center’s VAD volume and post-implant mortality. The authors say it could be that best practices have improved in VAD management since the early 2000s. Or the way the study was designed, which excludes post-heart transplant data, could be another explanation.

High-volume centers had fewer adverse events, specifically neurological dysfunction and late bleeding. And while the timing of the intervention and VAD type are likely contributors, a standard anticoagulation protocol following implantation is also important, he says.

Finally, failure to rescue, a metric to capture mortality following a morbidity event, was the same across all three center categories.

A call to action

Dr. Amdani argues that a progressive mindset is needed as experts consider the future of VAD support. “We will continue to navigate implantation in sick patients with complex anatomy, so we need to be proactive in identifying who needs a VAD and intervening before it’s too late.”

Regionalization of centers, a strategy recently endorsed by 15 medical societies, may be another useful strategy to improve outcomes. The consensus document recommends a two-tier structure in which lower-volume centers collaborate with a first-tier comprehensive care center when performing high-complexity pediatric transplant and VAD procedures.

Ultimately, the authors conclude that collaborative sharing of best practices among high-volume centers is imperative, particularly as low- and medium-volume centers make up more than half of pediatric centers in the U.S.

‘Surviving is a low bar’

Dr. Amdani hopes these findings will contribute to improving the VAD experience overall. “It’s not enough just to say a patient survived; that's a very low bar. You want a patient to survive with great outcomes, without any major adverse events such as stroke, bleeding or infection.”