Impact of the angle between aortic and mitral annulus on the occurrence of hemolysis during Impella support.

Despite optimal management, we sometimes experience refractory hemolysis requiring extensive device speed reduction or continuous hemodiafiltration following Impella implantation. However, pre-procedural predictors of such a refractory hemolysis remain unknown. In this study, we investigated the pre-procedural factors, including the echocardiographic narrow angle between aortic and mitral annulus, associating with the occurrence of refractory hemolysis following Impella insertion. We enrolled 26 patients (71 years, 65% male) who received Impella insertion between March 2018 and November 2019. Among baseline characteristics, the angle between aortic and mitral annulus, < 126.5°, was an independent risk factor of refractory hemolysis with an adjusted hazard ratio of 7.840 (95% confidence interval 0.925-66.44) and was associated with lower 30-day survival (64% vs. 100%, p = 0.0116). The narrow angle between aortic and mitral annulus might be a useful tool to risk-stratify the occurrence of refractory hemolysis following Impella insertion.