Performance of Risk Scores in Predicting Major Bleeding in Left Ventricular Assist Device (LVAD) Recipients: a Comparative External Validation

BACKGROUND Implantation of a left ventricular assist device (LVAD) is a crucial therapeutic option for selected end-stage heart failure patients. However, major bleeding (MB) complications post-implantation are a significant concern. OBJECTIVES We evaluated current risk scores’ predictive accuracy for MB in LVAD recipients. PATIENTS / METHODS We conducted an observational, single-center study of LVAD recipients (HeartWare or HeartMate-3, November 2010 - December 2022) in the Netherlands. The primary outcome was the time to first post-LVAD MB (according to ISTH, INTERMACS and INTERMACS combined with intracranial bleeding (INTERMACS+) criteria). Mortality prior to MB was considered a competing event. Discrimination (C-statistic) and calibration were evaluated for HAS-BLED, HEMORR2HAGES, ATRIA, OBRI, VTE-BLEED, AF-BLEED and UBRS. RESULTS 104 patients were included (median age: 64 years, female: 20.2%, HeartWare: 90.4%, HeartMate-3: 9.6%). The cumulative MB incidence was 75.7% (95%CI 65.5 – 85.9%) by ISTH and INTERMACS+ criteria, and 67.0% (95%CI 56.0–78.0%) per INTERMACS criteria, over a median event-free follow-up time of 1916 days (range: 59 – 4521 days). All scores had poor discriminative ability on their intended prediction timeframe. AUCt ranged from 0.49 (95%CI 0.35 – 0.63, VTE-BLEED) to 0.56 (95%CI 0.47 – 0.65, UBRS) according to ISTH and INTERMACS+, and from 0.48 (95%CI 0.40 – 0.56, ATRIA) to 0.56 (95%CI 0.47 – 0.65, UBRS) per INTERMACS criteria. All models showed poor calibration, largely underestimating MB risk. CONCLUSION Current bleeding risk scores exhibit inadequate predictive accuracy for LVAD recipients. There is a need for an accurate risk score to identify LVAD patients at high risk of MB who may benefit from patient-tailored anti-thrombotic therapy.