*Purpose: There is limited evidence evaluating the relationship between angiotensin II type 1 receptor antibodies (AT1R-Abs), donor-derived cell-free DNA (dd-cfDNA), and rejection in heart transplant recipients (HTRs). Data is also limited on the management of AT1R-Abs with angiotensin receptor blockers (ARBs) in HTRs.

*Methods: This was an institutional review board approved retrospective review of adult HTRs at VCU Health between 01/2016 and 12/2020 who had dd-cfDNA performed within 30 days of a biopsy and AT1R-Ab levels drawn post-transplant. Multiorgan and retransplant recipients were excluded. The primary outcome evaluated the relationship of post-transplant AT1R-Abs and dd-cfDNA on antibody-mediated rejection (AMR) and acute cellular rejection (ACR). The secondary outcome evaluated the effect of ARB initiation in HTRs with positive AT1R-Abs on AMR and ACR. Categorical variables were analyzed through chi-squared and continuous variables through student’s t-test. Pearson’s coefficient was used for correlation analysis.

*Results: A total of 43 HTRs were included. Median time from transplant to first AT1R-Ab and dd-cfDNA were 11 (4, 24) months and 9 (7, 23) months, respectively. Most patients were not sensitized with a mean class I and class II PRA of 4.6% and 6.6%, respectively. There was a clinically relevant trend towards higher mean peak AT1R-Ab levels in the 5 HTRs who had AMR within 1-year post-transplant versus the 38 HTRs without (34.9 vs 24.1 U/mL, p=0.53). This trend of higher mean peak AT1R-Ab levels persisted in 8 HTRs with overall AMR past 1-year post-transplant versus the 35 HTRs without (31.2 vs 24.0 U/mL, p=0.55). Similarly, there was a trend towards higher mean peak AT1R-Ab levels in 8 HTRs with ACR within 1-year post-transplant versus the 35 HTRs without (46.1 vs 20.6 U/mL, p=0.27) as well as in the 10 HTRs with overall ACR past 1-year post-transplant versus the 33 HTRs without (40.1 vs 20.1 U/mL, p=0.29). Elevated mean peak dd-cfDNA in the 8 HTRs with overall AMR versus the 29 HTRs without was seen (1.1 vs 0.31, p=0.20). A correlation between AT1R-Ab levels and dd-cfDNA was not observed (r²=0.004). The addition of an ARB resulted in a mean decrease in AMR grading of 0.25 (p=0.12) and a mean ACR grading difference of 0.05 (p=0.63).

*Conclusions: There was a clinical trend towards higher AT1R-Ab levels in HTRs with AMR or ACR post-transplant, compared with those who did not have rejection. There were additional trends towards ARB initiation decreasing the grade of AMR as well as dd-cfDNA rising in AMR. One limitation of this study was that the median time from transplant to first AT1R-Ab level was close to a year post-transplant, and most rejection episodes occurred within 1-year post-transplant. Future larger studies are warranted to validate the results of this study.

« Back to 2022 American Transplant Congress