Recipient Obesity and Heart Sizing: Gaining a Broader Understanding Within Heart Transplantation.

Area of Science:

• Cardiology
• Transplant Surgery
• Obesity Medicine

Background:

• Undersized donor hearts, defined by predicted heart mass ratio (PHMr), are linked to higher mortality in heart transplant recipients.
• The impact of obesity on outcomes for recipients of undersized hearts remains understudied.

Purpose of the Study:

• To investigate the interaction between body mass index (BMI) and PHMr on graft survival in adult heart transplant recipients.
• To determine if obesity exacerbates graft failure risk in patients receiving undersized donor hearts.

Main Methods:

• Analysis of adult, primary, solitary heart transplant recipients from the Scientific Registry of Transplant Recipients (2000-2020).
• Stratification of PHMr (undersized, matched, oversized) and BMI (under/healthy weight, overweight, obese).
• Utilized Kaplan-Meier and multivariable proportional hazards regression survival models.

Main Results:

• Both higher BMI and lower PHMr were independently associated with reduced graft survival (P < .05).
• A significant interaction effect between BMI and PHMr was observed (P = .052).
• Increasing BMI increased graft loss risk in matched and oversized heart recipients (P < .001), but not in undersized heart recipients (P = .124).

Conclusions:

• The association between BMI and graft failure is dependent on PHMr.
• Obesity does not further elevate graft failure risk in recipients already receiving undersized donor hearts.
• BMI's prognostic value for graft survival differs significantly between undersized and matched/oversized donor heart recipients.