Objectives: Haemolysis during left ventricular assist device support is associated with thrombosis. In this retrospective study, we analysed whether low-level haemolysis (LLH) as defined by simultaneously elevated lactate dehydrogenase (LDH) and free haemoglobin (fHb) levels had an impact on thromboembolic and bleeding events and on von Willebrand factor levels in HeartMate II patients.
Methods: After exclusion of patients with LDH >700 U/l and fHb >40 mg/dl at hospital discharge, 79 HeartMate II patients were included. LDH and fHb levels were measured at discharge and in 3 months interval. von Willebrand factor activity and antigen activity were measured 3 months postoperatively. Outcomes regarding ischaemic stroke (IS), pump thrombosis (PT) and gastrointestinal bleeding were recorded. Patients with LLH (400 < LDH ≤ 700 U/l and 30 < fHb ≤ 40 mg/dl) at discharge (pre-Hemolyzers) were compared with the rest of the cohort (non-Hemolyzers). Competing risk analysis and Cox regression were applied for the comparison between groups.
Results: In all, 20% of the patients were identified as pre-Hemolyzers. Of these, 5 patients had PT and 3 patients had IS compared with 2 PT and 2 IS in the non-Hemolyzers group (P = 0.003 and P = 0.053, respectively). Fifty percent of the pre-Hemolyzers suffered gastrointestinal bleeding compared with 42% of the non-Hemolyzers (P = 0.399). The cumulative risk of thromboembolic events (IS or PT) in the pre-Hemolyzers group was significantly higher compared with the non-Hemolyzers group (hazard ratio 11.8, 95% confidence interval 3.7-37.7; P = 0.005). LLH did not have an impact on von Willebrand factor and the incidence of gastrointestinal bleeding.
Conclusions: LLH as assessed by elevated fHb and LDH values at discharge during HeartMate II support is associated with thromboembolic events.