Thrombotic events with proliferation signal inhibitor‒based immunosuppression in cardiac transplantation

Some literature exists potentially linking proliferation signal inhibitors (PSIs) to venous thromboembolism (VTE). We sought to determine the impact of PSIs on development of VTE in heart transplant (HT) patients while controlling for other risk factors.

The incidence and predisposing factors of VTE were analyzed in this retrospective review of patients >18 years who underwent HT January 2000 to October 2016. Re-transplants, multiorgan transplants, or patients that expired within 30 days post-HT were excluded. VTE incidence rates are reported as number of events per 100 person-years. Cox proportional hazards models were used to assess the relationship between PSI exposure (time-varying covariate) and VTE.

Of 561 HT recipients, 112 received PSIs, started a median of 1.5 years post-HT. There were 102 total VTE events: 78 in PSI-naive patients during 2,547 patient-years (3.0 events per 100 person-years) vs 24 in PSI-exposed patients during 544 patient-years (4.4 events per 100 person-years). Cox proportional hazards models with PSI exposure as a time-varying covariate indicated the increased risk was statistically significant (unadjusted hazard ratio [HR] 2.14, 95% confidence interval [CI] 1.31 to 3.49, p = 0.002). A VTE history was significantly associated with increased risk of VTE post-HT (HR 1.58, 95% CI 1.07 to 2.35, p = 0.022); however, the risk remained significant when adjusting for potential confounders, including previous VTE (HR 2.0, 95% CI 1.18 to 3.38, p = 0.010).

Exposure to PSIs is associated with a significant increase in risk for VTE even when controlling for other risk factors. When considering the use of PSI-based immunosuppression after HT, the risk of VTE over time should be weighed against the potential benefit.