The Variation of Left Heart Size Based on Donor and Recipient Sex and Its Impact on Outcomes After Orthotopic Heart Transplant

Introduction: The impact of sex mismatch on outcomes after orthotopic heart transplant (OHT) remains unclear. We aimed to evaluate the change in left ventricle (LV) size based on donor and recipient sex and examine its association with the outcomes. Methods: This was a single institution, retrospective study among OHT recipients between Jan 2015 and Sept 2020. Patients were excluded if they were<18 years old, received OHT for congenital heart disease, had follow-up<6 months or missing donor variables. We collected donor (D) and recipient (R) clinical and echocardiographic characteristics. First and last echo post OHT were collected at least 2 months apart. Donor data was extracted from UNOS database. Primary outcome was the variation in donor heart size based on sex at first and last echo after transplant and the difference in survival or HF hospitalization. Statistical analysis (T test) was performed using Stata 15.1. Results: Among 156 reviewed patients, N=68 were included. Female (F) recipients (R) median age was 51±16 y, 25% were African-American (AA) while male (M) recipients median age was 56±12y and 19% were AA. Pre-transplant, MR had a higher RV and LV predicted heart mass and higher CO, CI by Fick. Aside from a higher prevalence of hypertension in MR, there was no difference in baseline characteristics. OHT allocation was MD/MR (66%); FD/FR (18%); FD/MR (4%); MD/FR (12%). LVEDD was bigger in MR on the first echo and remained on last echo post-transplant. There was no difference in degree of variation of LV parameters (LVEDD, LVESD, LV thickness) in MD/MR vs FD/MR and FD/FR vs MD/FR. Compared to sex matched, sex mismatched cohort had a non-significant trend towards a bigger degree of variation in LV size at first (-9% ± 10% vs -2% ± 21%;p=0.14) and last echo (-8% ± 12% vs -4% ± 14%;p=0.1).There were 18% (66% acute cellular rejection) cases of rejection split in half between sex matched and mismatched cohort. At a follow-up duration up to 6 years, 25% (N=17/68) of patients did not survive. There was no difference in survival or HF hospitalization in MR vs FR, in sex matched vs sex-mismatched. Conclusions: This is one of the first studies to examine the change in LV size and its impact on outcomes post OHT. The potential impact of LV behavior in M vs F is worth exploring on larger cohorts.