Morbidity and mortality in heart transplant candidates supported with mechanical circulatory support: is reappraisal of the current United network for organ sharing thoracic organ allocation policy justified?

Abstract

Background: Survival of patients on left ventricular assist devices (LVADs) has improved. We examined the differences in risk of adverse outcomes between LVAD-supported and medically managed candidates on the heart transplant waiting list.

Methods and results: We analyzed mortality and morbidity in 33,073 heart transplant candidates registered on the United Network for Organ Sharing (UNOS) waiting list between 1999 and 2011. Five groups were selected: patients without LVADs in urgency status 1A, 1B, and 2; patients with pulsatile-flow LVADs; and patients with continuous-flow LVADs. Outcomes in patients requiring biventricular assist devices, total artificial heart, and temporary VADs were also analyzed. Two eras were defined on the basis of the approval date of the first continuous-flow LVAD for bridge to transplantation in the United States (2008). Mortality was lower in the current compared with the first era (2.1%/mo versus 2.9%/mo; P<0.0001). In the first era, mortality of pulsatile-flow LVAD patients was higher than in status 2 (hazard ratio [HR], 2.15; P<0.0001) and similar to that in status 1B patients (HR, 1.04; P=0.61). In the current era, patients with continuous-flow LVADs had mortality similar to that of status 2 (HR, 0.80; P=0.12) and lower mortality compared with status 1A and 1B patients (HR, 0.24 and 0.47; P<0.0001 for both comparisons). However, status upgrade for LVAD-related complications occurred frequently (28%) and increased the mortality risk (HR, 1.75; P=0.001). Mortality was highest in patients with biventricular assist devices (HR, 5.00; P<0.0001) and temporary VADs (HR, 7.72; P<0.0001).

Conclusions: Mortality and morbidity on the heart transplant waiting list have decreased. Candidates supported with contemporary continuous-flow LVADs have favorable waiting list outcomes; however, they worsen significantly once a serious LVAD-related complication occurs. Transplant candidates requiring temporary and biventricular support have the highest risk of adverse outcomes. These results may help to guide optimal allocation of donor hearts.

Figure 1

Outcomes for heart transplant candidates on the United Network for Organ Sharing (UNOS) waiting list in the first era. A, Unadjusted waiting list survival according to UNOS status and left ventricular assist device (LVAD) support type. B, Unadjusted waiting list survival free from death or delisting as a result of worsening clinical status according to UNOS status and LVAD support type. CF indicates continuous flow; and PF, pulsatile flow.

Figure 2

Outcomes for heart transplant candidates requiring mechanical circulatory support on the United Network for Organ Sharing (UNOS) waiting list in the first era. A, Unadjusted waiting list survival and B, unadjusted waiting list survival free from death or delisting as a result of worsening clinical status. BIVAD indicates biventricular assist device; CF, continuous flow; LVAD, left ventricular assist device; PF, pulsatile flow; and TAH, total artificial heart.

Figure 3

Outcomes for heart transplant candidates on the United Network for Organ Sharing (UNOS) waiting list in the current era. A, Unadjusted waiting list survival according to UNOS status and left ventricular (LVAD) support type. B, Unadjusted waiting list survival free from death or delisting as a result of worsening clinical status according to UNOS status and LVAD support type. CF indicates continuous flow; and PF, pulsatile flow.

Figure 4

Outcomes for heart transplant candidates requiring mechanical circulatory support on the United Network for Organ Sharing (UNOS) waiting list in the current era. A, Unadjusted waiting list survival and (B) unadjusted waiting list survival free from death or delisting as a result of worsening clinical status. BIVAD indicates biventricular assist device; CF, continuous flow; LVAD, left ventricular assist device; PF, pulsatile flow; and TAH, total artificial heart.

Figure 5

Waiting list outcomes in left ventricular assist device (LVAD) recipients with and without complications in relation to United Network for Organ Sharing (UNOS) status groups in the first era. A, Unadjusted waiting list survival. B, Unadjusted waiting list survival free from death or delisting as a result of worsening clinical status. Time 0 for LVAD recipients with complications is the time of status 1A upgrade resulting from an LVAD complication. Time 0 for LVAD recipients without complications is the time of listing for transplantation with an LVAD.

Figure 6

Waiting list outcomes in left ventricular assist device (LVAD) recipients with and without complications in relation to United Network for Organ Sharing (UNOS) status groups in the current era. A, Unadjusted waiting list survival. B, Unadjusted waiting list survival free from death or delisting as a result of worsening clinical status. Time 0 for LVAD recipients with complications is the time of status 1A upgrade resulting from an LVAD complication. Time 0 for LVAD recipients without complications is the time of listing for transplantation with an LVAD.

Figure 7

Listing status upgrade as a result of left ventricular assist device (LVAD)–related complications in the current era. A, Survival free from listing status upgrade resulting from LVAD-related complications. Patients were censored at the time of transplantation, death, or delisting. B, Hazard function for the risk of listing status upgrade owing to LVAD-related complications.

Figure 8

Competing outcomes for heart transplant candidates supported with left ventricular assist devices (LVADs) while on the United Network for Organ Sharing waiting list. A, In the first era, after 6 months of LVAD support, 83% of the patients were alive on ongoing LVAD support (25%), transplanted (57%), or delisted because of clinical recovery (0.3%). The remaining 17% of the patients had died (16%) or had been delisted as a result of worsening clinical status (1%). B, In the current era, after 6 months of LVAD support, 94% of the patients were alive on ongoing LVAD support (48%), transplanted (46%), or delisted because of clinical recovery (0.2%). The remaining 6% of the patients had died (5%) or had been delisted as a result of worsening clinical status (1%).