The influence of preoperative use of ventricular assist devices on survival after heart transplantation: propensity score matched analysisBMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c392 (Published 10 February 2010) Cite this as: BMJ 2010;340:c392
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Fallacies, contradictions, and statistics of clinical outcomes related to surgical implantation of the left ventricular assist device as a bridge to heart transplantation
The persuasive power of numbers, particularly the use of statistics
to bolster weak arguments can not be ignored in medical practice.
The use of a ventricular assist device (VAD) as a bridge to heart
transplantation and the attributed morbidity and mortality after heart
transplantation has produced conflicting data analysis literature (1-4).
Patlolla et al (1) compared 1,433 patients bridged with
intracorporeal and 448 patients bridged with extracorporeal VADs to 9,455
the United Network for Organ Sharing (UNOS) status 1 patients not bridged
with a VAD with respect to post-transplant mortality. The authors
concluded “Extracorporeal VADs are associated with higher mortality within
6 months and again beyond 5 years after transplantation. Intracorporeal
VADs are associated with a small increase in mortality in the first 6
months and a clinically significant increase in mortality beyond 5 years.
These data do not provide evidence supporting VAD implantation in stable
United Network for Organ Sharing status 1 patients awaiting heart
In response to the above study, Russo et al (2) re-examined the UNOS
database of 10,668 orthotopic heart transplant recipients aged 18 years
old or older and undergoing transplantation between January 1, 2001, and
December 31, 2006. The authors examined bridge-to-transplant recipients by
type of VAD: extracorporeal, paracorporeal, and intracorporeal. Russo et
al concluded: “The use of implantable left ventricular assist devices
[LVAD] as bridges to transplantation, including both intracorporeal and
paracorporeal devices is not associated with diminished posttransplant
survival. However, 90-day survival was diminished in recipients bridged
with extracorporeal devices”
Pal et al (3) retrospectively reviewed UNOS database status 1 heart
transplant recipients who were bridged to transplant with an LVAD or with
intravenous inotropes only from 1994 to 2007. They concluded: “Patients
bridged to transplant with a LVAD represent a subset of UNOS status 1
patients who deteriorated on intravenous inotropic therapy. Bridging to
heart transplantation with an implantable LVAD provides comparable
outcomes to similar status 1 patients who were stabilized on inotropic
infusions only. In contrast with International Society of Heart and Lung
Transplantation data, no increase in posttransplant morbidity or mortality
occurred in LVAD-bridged patients.”
Shuhaiber et al. (4) reexamined the same database from UNOS Registry,
1996-2004, with a different statistical analysis (propensity score
matching) to conclude that “overall, survival after heart transplantation
in patients who received a left ventricular assist device before
transplantation was comparable to those who did not receive the device”
In clinical practice, surgical implantation of an LVAD has
significant attributable morbidity, mortality and asymmetric utilization
of resources. This can be illustrated in patients who are not candidate
for heart transplantation, and have LVAD implanted permanently in
destination therapy (5). For example, the HeartMate II is an LVAD (a
second generation axial flow non-pulsatile device) that is used in
clinical practice both as a bridge to transplant and a destination therapy
(5). A recent study reported the incidence of significant complications in
recipients of this particular device: 35% infection , 81% bleeding
requiring transfusion, 30% bleeding requiring surgery , 22% neurologic
events, and 94% re-hospitalization (5). In a Literature review of LVAD
(6), surgery to implant an LVAD has a hospital (30- to 90-day) mortality
of 14% to 27%. The average total hospital cost of surgical implantation of
LVAD is between $159,271 and $315,015 per recipient.
The studies examining post-transplant outcome of LVAD recipients,
exclude those patients failing to be successfully transplanted because of
death or serious complications from the device itself. This introduces
bias in the clinical impression about safety and implantation cost of
these devices. The data on those transplant candidates who may have died
or are no longer transplant candidates because of adverse clinical events
from these devices should be included for an accurate clinical evaluation
of an LVAD as a bridge to transplant.
Clinical reasoning can often identify serious flaws or
inconsistencies of conclusions inferred from statistical analyses.
1. Patlolla V, Patten RD, DeNofrio D, Konstam MA, Krishnamani R. The
Effect of Ventricular Assist Devices on Post-Transplant Mortality: An
Analysis of the United Network for Organ Sharing Thoracic Registry. J Am
Coll Cardiol. 2009;53:264-271.
2. Russo MJ, Hong KN, Davies RR, et al. Posttransplant survival is
not diminished in heart transplant recipients bridged with implantable
left ventricular assist devices. J Thorac Cardiovasc Surg. 2009;138:1425-
3. Pal JD, Piacentino V, Cuevas AD, et al. Impact of Left Ventricular
Assist Device Bridging on Posttransplant Outcomes. Ann Thorac Surg.
4. Shuhaiber JH, Hur K, Gibbons R. The influence of preoperative use
of ventricular assist devices on survival after heart transplantation:
propensity score matched analysis. BMJ. 2010;340:c392.
5. Slaughter MS, Rogers JG, Milano CA, et al. Advanced Heart Failure
Treated with Continuous-Flow Left Ventricular Assist Device. N Engl J Med.
6. Rizzieri A, Verheijde J, Rady M, McGregor J. Ethical challenges
with the left ventricular assist device as a destination therapy. Philos
Ethics Humanit Med. 2008;3:20. Available at: http://www.peh-
Joseph L. Verheijde, PhD, MBA
Associate Professor of Biomedical Ethics, College of Medicine, Mayo
Department of Physical Medicine and Rehabilitation,
Mayo Clinic, Phoenix, Arizona, 85254, United States of America
Mohamed Y. Rady, MD, PhD
Professor of Medicine, College of Medicine, Mayo Clinic
Consultant, Department of Critical Care Medicine , Mayo Clinic Hospital,
Mayo Clinic, Phoenix, Arizona, 85254, United States of America
Competing interests: No competing interests