Changes in bloodstream infections in heart transplant recipients following the allocation guidelines change

Area of Science:

• Cardiology
• Transplantation Immunology
• Infectious Diseases

Background:

• The 2018 US orthotopic heart transplant (OHT) policy revision prioritized critically ill patients, including those on temporary mechanical circulatory support (tMCS).
• Assessing the impact of this policy change on post-transplant bloodstream infection (BSI) rates is crucial for patient outcomes.

Purpose of the Study:

• To evaluate the association between the 2018 OHT allocation policy change and the incidence of post-transplant bloodstream infections (BSI).
• To explore the mediating role of temporary mechanical circulatory support (tMCS) in the relationship between the policy change and BSI risk.

Main Methods:

• Retrospective cohort study of 895 OHT recipients at two US transplant centers (2015-2022).
• Analysis of BSI rates within 90 days post-OHT using multivariable Cox regression.
• Mediation analysis to assess the effect of tMCS on BSI risk.

Main Results:

• A >2.5-fold increase in pre-transplant tMCS use was observed post-policy change.
• The incidence of BSI was 10.6% (95 recipients).
• Orthotopic heart transplant (OHT) in the post-policy era was associated with a 2.3-fold increased hazard of BSI (P=0.002), with tMCS explaining only part of this increase.
• One-year mortality and graft failure rates remained similar, but one-year rejection significantly decreased (P<0.001).

Conclusions:

• Post-transplant bloodstream infection (BSI) risk doubled after the 2018 OHT policy change, exceeding the impact attributable to increased temporary mechanical circulatory support (tMCS) use.
• While the policy change led to reduced rejection, additional factors beyond tMCS likely contribute to the elevated BSI risk.
• Further investigation is warranted to identify and mitigate the drivers of increased BSI post-heart transplantation under the revised allocation policy.