Bleeding and thrombotic events during micro-axial flow pump support: A European multicenter cohort study.

BACKGROUND: Bleeding and thrombosis are major complications of micro-axial flow pump (mAFP) support in cardiogenic shock (CS), yet contemporary data on their incidence, temporal trends, and prognostic impact remain unclear. METHODS: We retrospectively analyzed patients supported with mAFP between 2010 and 2023 across eleven high-volume European centers. Bleeding and thrombotic events during support were adjudicated and normalized to annual implant volumes. Kaplan–Meier analysis assessed 180-day survival, and multivariable logistic regression identified independent predictors of bleeding and thrombosis. RESULTS: Among 1,043 patients (61% acute myocardial infarction related CS), Impella CP was used in 72% and Impella 5 in 28%. Overall, 503 patients (48%) experienced ≥ 1 event: 252 bleeding only, 149 thrombosis only, and 102 both. Independent predictors of bleeding were post-cardiotomy CS (OR 2.64; 95% CI, 1.41–4.96; p = .003), Acute myocardial infarction related CS (AMICS) (OR 2.27; 95% CI, 1.38–3.74; p = .001), V-A ECMO unloading indication (OR 1.65; 95% CI, 1.14–2.39; p = .008) and renal replacement therapy at implantation (OR 1.56; 95% CI, 1.08–2.27; P = .019). Predictors of thrombosis were prior stroke (OR 2.51; 95% CI 1.40–4.51), AMI-CS (OR 2.06; 95% CI 1.42–3.00), and mAFP unloading with V-A ECMO (OR 2.03; 95% CI 1.38–2.98). Bleeding (OR 1.38; 95% CI 1.02–1.87) and thrombosis (OR 2.10; 95% CI 1.53–2.88) were independently associated with higher 180-day mortality. CONCLUSIONS: In this large European mAFP cohort, bleeding and thrombotic events were frequent and associated with mortality and adverse outcomes. Their distinct risk profiles support individualized prevention strategies and underscore the need for prospective randomized trials comparing anticoagulation regimens in risk-stratified patients.