This article reviews the fourth report of pediatric patients included in the European registry of long-term VADs (Paedi-EUROMACS). The study encompasses 590 primary long-term VAD implants (uni- or biventricular) in patients under 19 years of age during a 21-year period (2001–2022). A total of 29 hospitals across 15 countries, primarily European, participated in this registry. The primary endpoints analyzed were VAD explantation due to death, heart transplantation, or recovery of cardiac function. Secondary endpoints included thromboembolic, infectious, and cerebrovascular complications, as well as right ventricular failure, respiratory failure, and renal dysfunction in VAD recipients.
The predominant initial diagnosis was cardiomyopathy in 68% (mainly dilated), congenital heart disease (CHD) in 17%, and acute myocarditis in 15%. Patients with CHD were significantly younger, clinically more compromised, had higher rates of prior surgeries, and were more often implanted with pulsatile-flow devices compared to patients with cardiomyopathy.
The primary indication for VAD implantation was bridge to transplant (63%), potential bridge to transplant (26%), with destination therapy being anecdotal in children (0.5%). Regarding the type of VAD implanted, 62% were paracorporeal devices (predominantly Berlin Heart EXCOR®), and 36% were intracorporeal devices (primarily HeartWare®). Most VADs provided univentricular support (85%), including 10 patients with a single ventricle. In 15% of cases, biventricular support was utilized. The median duration of support was 3.9 months.
Observed outcomes at two years in the overall cohort for primary endpoints showed that 59.7% underwent transplantation, 22% died, and 10% recovered. Patients with CHD had higher mortality and lower transplantation rates compared to those with cardiomyopathy. The leading causes of death were stroke and multiorgan failure. Multivariate analysis identified INTERMACS profile I and the need for prior extracorporeal membrane oxygenation (ECMO) as risk factors for mortality. However, CHD was not a risk factor for mortality in this study. Among adverse events associated with VADs, pump thrombosis was the most frequent complication, followed by infections and strokes. Multivariate analysis of pump thrombosis risk factors associated this complication with smaller body surface area and pulsatile-flow devices. Patients with CHD exhibited higher rates of pump thrombosis, malfunction, and infection, while those with cardiomyopathy experienced more arrhythmias. Smaller body surface area was also a risk factor for stroke, and postoperative bleeding was linked to INTERMACS I profile and prior ECMO use.
COMMENTARY:
As in adults, the use of long-term VADs in children as a treatment for end-stage heart failure is steadily increasing. Due to the relatively small number of pediatric VAD implants compared to adults, collaborative studies among hospitals are essential to identify trends, evaluate outcomes, and draw conclusions about this therapy in the pediatric population. This fourth Paedi-EUROMACS report includes 590 primary long-term VAD implants (uni- or biventricular) in patients under 19 years of age over a 21-year period.
The primary diagnosis of children requiring VADs remains cardiomyopathy, although the proportion of CHD patients has increased compared to the previous European report, albeit still lower than in the American registry (17% in Paedi-EUROMACS vs. 25% in PEDIMACS).
In this pediatric cohort, VADs were primarily implanted as a bridge to transplant. These devices have reduced waiting list mortality and enabled a higher percentage of children to reach transplantation.
Among the implanted devices, 62% were pulsatile-flow devices (primarily Berlin Heart EXCOR®). In the 36% intracorporeal group, HeartWare® was predominant, though its market withdrawal in 2021 is expected to lead to increased use of Berlin Heart EXCOR® and HeartMate3®.
Univentricular VADs were generally implanted (85%), while 15% received biventricular support. Ten patients with single ventricles and univentricular VADs were not separately analyzed, likely due to their small numbers, though these cases may increase in the future as terminal heart failure is a common manifestation in this population over time.
The two-year outcomes observed in the overall cohort were promising, with nearly 60% undergoing transplantation, 22% dying, and 10% recovering. Despite modifications to anticoagulant and antiplatelet protocols, pump thrombosis remains the most frequent adverse event, associated with pulsatile-flow devices and smaller body surface area.
This study compared CHD and cardiomyopathy populations, revealing that the former were significantly younger, had worse clinical conditions, more prior surgeries, and more pulsatile-flow devices. CHD patients also had higher mortality and lower transplantation rates compared to cardiomyopathy patients.
Multivariate analysis identified INTERMACS I profile and prior ECMO use as risk factors for mortality and postoperative bleeding. These factors have also been associated with poorer outcomes in adult VAD patients.
In conclusion, the use of long-term VADs in pediatric patients is increasing and serves as an effective tool to achieve transplantation or VAD explantation due to cardiac recovery in up to 70% of cases. While nonmodifiable factors such as weight or cardiac diagnosis exist, preimplant clinical condition can be optimized. Timing of VAD implantation should consider these factors to avoid excessively early or delayed interventions, aiming for the best possible outcomes.
REFERENCES:
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Menéndez JJ, Sánchez-Galindo AC, Balcells J, Tejero-Hernández MA, Ferrer-Barba Á, Ibiza-Palacios E, et al. Short- and long-term survival of children treated with ventricular assist devices in Spain, based on 15 years’ experience. European Journal of Cardio-Thoracic Surgery, Volume 63, Issue 2, February 2023, ezad050, https://doi.org/10.1093/ejcts/ezad050
Adachi I, Peng DM, Hollander SA, Simpson KE, Davies RR, Jacobs JP, et al Sixth Annual Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) Report The Society Of Thoracic Surgeons Pedimacs Annual Report. The Annals of Thoracic Surgery (2023), 115: 1090-1108. doi:10.1016/j.athoracsur.2022.10.042
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