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

Abstract

Abstract Background Hemolysis of Impella is known as a major comorbidity and adequate device positioning and optimization of volume status are recommended. However, we have sometimes experienced hemolysis refractory to these adjustments and anatomical feature appears to be crucial in such cases. Methods We enrolled 26 patients (median 71 y; BSA 1.6 m2; LVEF 27%) with cardiogenic shock who received Impella insertion from March 2018 to November 2019. The angle of the aortic and mitral annulus which was drawn at the apical 3-chamber view on echocardiography, just before or after Impella insertion was measured (Figure). Hemolytic event was defined as follows; (1) Gross dark red urine and elevation of serum LDH level after initiation of Impella support were seen and subsequently required to lower the support level of Impella under P6. (2) Blood sample data indicating hemolysis (i.e. elevation of LDH level over 1.5 fold of normal range, anemia complicated with decreased haptoglobin, the elevation of total bilirubin level accompanied indirect bilirubin elevation) was found and subsequently required to initiate continuous hemodiafiltration. Results The freedom from hemolytic event was significantly lower in the narrow angle group (<126.5 degrees, Figure A) compared with the wide angle group (≥126.5 degrees, Figure B) (18% vs 83%, p<0.0001). The narrow angle was a significant risk factor of hemolytic event with an unadjusted hazard ratio 13.9 (95% confidence interval 2.88–67.2, p=0.0499) and a hazard ratio 15.5 (95% confidence interval 3.15–76.3, p=0.0008) adjusted for lower pulmonary artery pulsatility index, which was another risk factor significant in the univariate analyses. Furthermore, 30-day survival rate was significantly lower in the narrow angle group compared with the wide angle group (63% vs 100%, p=0.0116). Conclusions The narrow angle (<126.5 degrees) was an independent risk factor of hemolytic event and 30-day survival was lower compared with the wide angle group. Figure 1 Funding Acknowledgement Type of funding source: None