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

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.