Increasing heart transplant donor pool by liberalization of size matching

Abstract

BACKGROUND-The heart transplant (HT) guidelines recommendation to match recipient and donors within 30% of body weight lacks a strong evidence base and is not well established in patients bridged to transplant with left ventricular assist devices (LVAD). In light of the scarcity of donor hearts, we investigated the effect of size mismatch on hemodynamics, one-year survival and length of stay (LOS) following HT. METHODS-Single-center retrospective analysis of consecutive HT patients from April 2007 to September 2017. Recipients were divided into 3 cohorts based on donor-to-recipient weight ratio (DRWR): (1) undersized (<0.7), (2) size-matched, (0.7-1.3); (3) oversized (>1.3). RESULTS-288 consecutive patients were identified (mean age 53 ± 11 years; 76% male), 46 were undersized (0.61 ± 0.05), 210 size-matched (0.94 ± 0.16), and 32 oversized (1.65 ± 0.38). There was no significant difference in donor left ventricular end diastolic diameter (LVEDD) between the 3 groups (p = 0.11). The donor/recipient (D/R) predicted heart mass (PHM) was lowest in the undersized group (0.92 ± 0.13). There were no significant differences in 1-year survival in the overall and LVAD cohort (p = 0.65 and 0.59, respectively). Neither donor LVEDD nor D/R PHM differed among survivors or non-survivors. LOS was longer in the undersized group than the size-matched cohort (p = 0.004). The undersized group had hearts with the highest filling pressures and lowest cardiac index at 1 week among the remaining groups (p = 0.009, 0.017, and p = 0.05, respectively). There were no clinically significant differences in hemodynamics at 1 or 6 months.

Cardiac Surgery in Advanced Heart Failure

“…On the other hand, 32% of the donor hearts that were declined due to concerns of undersizing in the UNOS database of the years 2007 to 2016 were found eligible when using the heart mass as a parameter for matching metrics. While these results promise to improve the allocation of female donor hearts, a smaller study of 288 HTx recipients showed that undersizing of the donor heart affects early hemodynamics but was without impact on one-year survival [86]. Altogether, these results suggest that efforts to improve matching metrics have the potential to increase the allocation of donor organs judged not suitable based on current recommendations.…”

Reducing the wait: TCV can expand the donor pool for heart transplant candidates

“…1,2,6,11,12 This type of targeted size matching allows avoidance of complications related to oversizing, such as bronchial compression, delayed chest closure, and prolonged length of stay. 13,14 F I G U R E 1 The TCV segmentation is shown in the axial plane (A), coronal plane (B), and 3-dimensional reconstruction (C). TCV mass is in Red and HMIII is in green…”

“…Lacking a heart size measure like PHM in children, TCV‐based size matching has recently emerged as a method for more precise organ matching and has demonstrated on numerous occasions the potential to expand the donor pool for listed patients 1,2,6,11,12 . This type of targeted size matching allows avoidance of complications related to oversizing, such as bronchial compression, delayed chest closure, and prolonged length of stay 13,14 …”

Pediatric urgent heart transplantation with age or weight mismatched donors: Reducing waiting time by enlarging donor criteria

“…Current indications in adult heart transplantation consider an ideal DRWR to be between 0.8 and 1.2, but there are several studies on the impact of greater size mismatch, and it seems that is not associated with a higher mortality. [11][12][13] In the pediatric transplant population, these constraints have always been handled less rigidly as organ size discrepancies between children may have less impact than in adults and waiting times for ideal matches could be excessive due to limited pediatric donor availability. The consequences of enlarging the matching criteria have been largely debated, mostly about early and late complications.…”