- This study of United Network for Organ Sharing (UNOS) data compared post-transplant survival in patients bridged with temporary circulatory support–ventricular assist devices (TCS-VADs), extracorporeal membrane oxygenation (ECMO) or left-ventricular assist devices (LVADs)
- In unadjusted analyses, patients supported with any type of TCS-VAD had improved survival compared with those supported with ECMO, and this finding remained consistent in propensity-matched comparisons of all TCS-VAD types versus ECMO
- When only biventricular TCS-VADs were considered, survival was superior to ECMO in the unadjusted analysis; however, this difference was not significant in the propensity-matched analysis
- On multivariable analysis, ECMO was associated with a 2.4 times increased risk of death compared with TCS-VAD (95% CI, 1.44–4.01; P = .001)
- There was no difference in post-transplant survival when TCS-VAD was compared with LVAD
Durable continuous-flow left-ventricular assist devices (LVADs) are the gold-standard bridge to transplant for adults with end-stage heart failure refractory to medical management. However, patients bridged with extracorporeal membrane oxygenation (ECMO; up to 7 days) or temporary circulatory support–ventricular assist devices (TCS-VADs; up to 14 days) now have status 1 or 2 in the United Network for Organ Sharing (UNOS) heart allocation system.
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The new UNOS system allocates hearts to the sickest patients first, to decrease mortality on the waiting list, without attention to the probability of survival after transplant. Philicia Moonsamy, MD, clinical surgical fellow, Andrea L. Axtell, MD, MPH, cardiothoracic surgical fellow, and Mauricio A. Villavicencio, MD, MBA, director of Lung Transplantation in the Division of Cardiac Surgery at Massachusetts General Hospital, and colleagues have demonstrated that post-transplant survival is better when patients are bridged with TCS-VADs than with ECMO. Their investigation was published in The Journal of the American College of Cardiology.
Using the UNOS database, the researchers assembled a cohort of 24,905 patients who underwent heart transplantation between January 2005 and March 2017. Some were bridged with:
- Durable LVAD (9%)
- TCS-VAD (0.8%; 41% of these were biventricular)
- ECMO (0.7%)
Post-transplant survival was significantly better with TCS-VAD than with ECMO and was similar when TCS-VAD was compared with LVAD. The superiority of TCS-VAD to ECMO held true when only biventricular TCS-VAD was considered.
Propensity score matching is a way to estimate the effect of an intervention by accounting for the covariates that predict receiving the intervention. 35 variables were used to generate propensity-matched groups (75 patients in each group when TCS-VAD was compared with ECMO, and 199 in each group when TCS-VAD was compared with LVAD).
Again, post-transplant survival was better with TCS-VAD than with ECMO. There were no differences in survival for biventricular TCS-VAD versus ECMO or for all TCS-VAD types versus LVAD.
ECMO was associated with a 2.4 times increased risk of death compared with TCS-VAD (95% CI, 1.44–4.01; P = .001). The risk was not increased when ECMO was compared with biventricular TCS-VAD only.
Increased bilirubin was a predictor of death in the LVAD versus TCS-VAD model but not in the ECMO versus TCS-VAD models. Pre-transplant dialysis and mechanical ventilation were consistent predictors of death across the three models.
Considerations for Transplant Centers
TCS-VAD should be the preferred bridge to transplant when an LVAD is contraindicated (e.g., biventricular failure, small left-ventricular cavities with hypertrophic and restrictive cardiomyopathy, contraindication to long-term anticoagulation, renal failure or rapid availability of organs).
Besides post-transplant survival, advantages of TCS-VADs over peripheral ECMO are larger cannula sizes and improved flow, direct left-ventricular venting, avoidance of peripheral vascular complications, no oxygenator and less anticoagulation needed, easier management of air emboli and longer time for recovery.
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