Serial assessment of HeartMate 3 pump position and inflow angle and effects on adverse events

Abstract

Objectives: This study analyses the position of the HeartMate 3 left ventricular assist device on serial radiographs to assess positional change and possible correlation with adverse events.

Methods: We retrospectively analysed 59 left ventricular assist device recipients who had serial chest radiographs at 1 month, 6 months and 12 months post-implantation between November 2014 and June 2018. We measured pump angle, pump-spine distance and pump-diaphragm depth and investigated their relationship to a composite outcome of heart failure readmission, low flow alarms, stroke or inflow/outflow occlusion requiring surgical repositioning through recurrent event survival modelling.

Results: Between 1 and 6 months, the absolute pump-spine distance changed by 10.00 mm (P < 0.01) and the absolute pump-diaphragm depth changed by 18.80 mm (P < 0.01). These parameters did not change significantly between 6 and 12 months post-implantation. Pump angle did not change significantly over any period. Twenty-six patients experienced the composite outcome; in these patients, the median 1-month pump angle was 66.2° (interquartile range 54.5-78.0) as compared to 59.0° (interquartile range 47.0-65.0) in the 33 patients who did not have adverse events (P = 0.04). Pump depth and pump-spine distance at 1 month were not associated with the composite outcome. Change in pump depth between 1 and 6 months [hazard ratio (HR) 1.019; 95% confidence interval (CI) 1.000-1.039] and between 6 and 12 months (HR 1.020; 95% CI 1.000-1.040) were weakly associated with the composite outcome.

Conclusions: Larger pump angles are associated with the composite outcome of position-related adverse events. Pump depth movement is weakly associated with the composite outcome.

Keywords: HeartMate 3; Left ventricular assist device; Mechanical circulatory support; Pump movement.