Risk factors for massive postoperative bleeding after orthotopic heart transplantation: a retrospective cohort study

Orthotopic heart transplantation (OHT) remains the gold standard for patients with end-stage heart failure; however, postoperative bleeding is a frequent and clinically significant complication associated with increased morbidity and transfusion requirements. Data on predictors of massive bleeding in this population remain limited, particularly regarding the role of viscoelastic testing.

We conducted a single-center retrospective cohort study including 75 adult patients who underwent OHT between 2019 and 2025. Patients with incomplete data or without preoperative viscoelastic testing (ClotPro) were excluded. The primary endpoint was massive postoperative bleeding defined as ≥BARC III. Secondary endpoints included transfusion requirements, reoperation for bleeding, and postoperative blood loss. Univariate and multivariable logistic regression analyses were performed to identify independent predictors. Receiver operating characteristic (ROC) analysis was used to assess discriminative performance. This study was conducted in accordance with the principles of the Helsinki Declaration and the Istanbul Declaration. No organs were procured from prisoners or from individuals subjected to coercion or financial incentives.

Massive postoperative bleeding occurred in 31 patients (41.3%). Transfusion requirements were high, with red blood cells administered in 69.3%, plasma in 90.7%, and cryoprecipitate in 34.7% of patients. Reoperation for bleeding was required in 16.0% of cases. In univariate analysis, ECMO support, lower platelet count, lower fibrinogen, elevated INR, lower EX-test MCF, higher TPA-test ML, and longer cardiopulmonary bypass duration were associated with bleeding. In multivariable analysis, only EX-test MCF remained an independent predictor (OR 0.91 per 1 mm increase; 95% CI 0.85-0.98; p = 0.011).

Massive bleeding after OHT is common and associated with significant transfusion burden. Reduced EX-test MCF is an independent predictor of bleeding and may serve as a valuable tool for early risk stratification and personalized hemostatic management in heart transplant recipients.