Increasing heart transplant donor pool by liberalization of size matching

Area of Science:

• Cardiology
• Transplant Surgery
• Medical Guidelines

Background:

• Current heart transplant (HT) guidelines recommend matching donor and recipient body weights within 30%, a recommendation lacking robust evidence.
• This guideline is particularly uncertain for patients bridged to transplant with left ventricular assist devices (LVAD).
• Investigating the impact of donor-to-recipient size mismatch is crucial due to the scarcity of donor hearts.

Purpose of the Study:

• To evaluate the effect of donor-to-recipient size mismatch on hemodynamic function, one-year survival, and length of stay (LOS) after heart transplantation.
• To challenge the existing restrictive weight-matching guidelines in heart transplantation.

Main Methods:

• A single-center retrospective analysis of 288 consecutive heart transplant recipients from April 2007 to September 2017.
• Patients were categorized into three groups based on donor-to-recipient weight ratio (DRWR): undersized (<0.7), size-matched (0.7-1.3), and oversized (>1.3).
• Hemodynamic parameters, one-year survival, and LOS were compared across the cohorts, including a subgroup of LVAD patients.

Main Results:

• No significant differences in one-year survival were observed between the undersized, size-matched, and oversized groups, overall and in the LVAD cohort.
• Undersized transplants showed transiently higher filling pressures and lower cardiac index at one week post-transplant, with no significant long-term hemodynamic differences.
• Length of stay was significantly longer in the undersized group compared to the size-matched group.

Conclusions:

• Heart transplant undersizing impacts early hemodynamics but does not affect one-year survival.
• Liberalizing donor-to-recipient size matching criteria could significantly increase the available donor heart pool.
• Current weight-matching guidelines may be overly restrictive and could be re-evaluated based on these findings.