Immune Response in Heart Transplant Patients Following COVID-19 Vaccination

PURPOSE: Previous studies have described poor outcomes in heart transplant patients who develop COVID-19 infection. Therefore, we sought to characterize a single center's experience with heart transplant patient outcomes during the COVID-19 pandemic and the recent role of vaccination in mitigating the risk of mortality. METHODS: From a single center, we identified all orthotopic heart transplant patients alive at the beginning of the COVID-19 pandemic in March 2020. All patients were followed from the start of the pandemic until their most recent follow up or death. Baseline comorbidities and immediate outcomes data were obtained from the Society for Thoracic Surgery (STS) Adult Cardiac Surgery Database (ACSD). Multiple logistic regression analyzed the association between vaccination status, baseline covariates, and other standard STS outcome measures. Non-parametric tests were used to compare different subgroups. RESULTS: We included 153 patients, of which 20.9% developed COVID-19 infection (32/153) with 40.6% (13/32) requiring hospitalization and 15.6% of those patients (5/32) dying as a direct result of COVID-19 pneumonia. Kaplan-Meier survival analysis revealed that unvaccinated patients had a significantly higher rate of all-cause mortality as compared to those patients that were fully vaccinated despite similar baseline characteristics (p < 0.001). Patients with previous COVID-19 infection in addition to vaccination had significantly higher IgG titers as compared to those only vaccinated (6568.50 AU/mL vs. 58.05 AU/mL, p = 0.002). CONCLUSION: Immunization against COVID-19 is associated with a significant reduction in the mortality of heart transplant patients. IgG titers were variable among heart transplant patients who received the vaccine with the highest titers seen in those patients with a personal history of COVID-19. The implications of IgG levels are still unknown.