Abstract Background Haemolysis is a common complication during microaxial flow pump (mAFP) support in cardiogenic shock (CS) and significantly impairs clinical outcomes. Identifying factors contributing to haemolysis is crucial to improve patient management and survival. Purpose This study aimed to investigate factors associated with haemolysis in CS patients supported by left-sided mAFP for ≥ 24 hours. Methods In a retrospective two-center study of CS patients treated with left-sided mAFP, we examined clinical, echocardiographic and device-related parameters to identify predictors of haemolysis. Haemolysis was defined by plasma-free hemoglobin (pfHb) ≥40 mg/dL. Results A total of 102 patients were included from two centers, with a median age of 59 years (IQR 52-66, 83.3% male). The underlying cause of CS was ischaemic in 59.8% and non-ischaemic in 40.2%. During mAFP treatment, 56.9% (n=58) of patients experienced haemolysis, which typically began at a median of 1 day (IQR 1-2) post-implantation and lasted a median duration of 1 day (IQR 1-3). Patients with and without haemolysis had similar demographic profiles regarding age, gender and comorbidities. In univariate analysis, RV dysfunction (67.3% vs. 46.5%, OR 2.37 1.04–5.53, p=0.043) and higher pump flow (P-level 6.8 vs. 6.1, OR 1.41 1.04–1.96, p=0.031) were predictors of haemolysis. In multivariate analysis, a deeper than recommended inlet position showed borderline significance (OR 3.65 1.01–15.79, p=0.0604). Echocardiographic data revealed that a lower mAFP/mitral valve (MV) angle (49.0° vs. 58.5°, OR 1.06 1.01–1.11, p=0.019) was a significant predictor. A mAFP orientation closer to the anterior MV leaflet increases the risk of mechanical interaction, suggests device malrotation, and raises the risk of haemolysis (Figure 1a). AV/MV angles, defined as the angle between the aortic and mitral valve annuli (Figure 1b), were measured on echocardiography and categorised into tertiles: narrow (≤124.5°), intermediate (124.5° to ≤134°), and wide (134°). In multivariate analysis, narrow angles independently increased haemolysis risk compared to intermediate angles (OR 8.55 2.16–42.20, p=0.0041), adjusting for P-level, TAPSE, CS cause, and inlet depth. This suggests that a shallow AV/MV angle enhances mAFP interaction with the mitral valve, increasing haemolysis risk. Conclusion Our analysis identifies key echocardiographic and device-related factors linked to haemolysis in mAFP therapy. A narrow AV/MV angle emerged as an independent predictor, while deep inlet positioning showed borderline significance as a risk factor. These findings highlight the need for continuous echocardiographic evaluation during pump support to assess haemolysis risk, guide early intervention, and optimise device positioning, potentially improving outcomes. This hypothesis-generating study lays the groundwork for research in the (mal)position domain of mAFP.Echographic predictors of haemolysis AV/MV ≤124.5° increases haemolysis risk
Rossignon et al. (Sat,) studied this question.