Incidence and Cause of Persistent Low Flow Alarm after HeartMate 3 Left Ventricular Assist Device Insertion

Purpose This study sought to determine the incidence and cause of readmission due to persistent low flow alarms after HM3 LVAD implantation. Methods We retrospectively reviewed 135 patients who received HM3 LVAD between November 2014 and December 2018 in our single center. Patients who required readmission due to persistent low flow alarms were identified and analyzed. Cumulative incidence function curve was constructed for probability of low flow alarm readmission. Results Twenty-three patients (17.4%) required 28 readmissions due to persistent low flow alarms during median follow up of 11.2 months. The incidence of readmissions with persistent low flow alarms was 1.31 person-years. The probability of low flow alarm readmission was 17.7% at 1-year. Of 23 patients, 4 patients (17.4%) required multiple readmissions. The etiology of persistent low flow alarms is summarized in Table: Hypovolemia was present in 11 (39.3%) and hypertension was present in 16 (17.8%). Inflow or outflow obstruction requiring surgical intervention was present in 5 (17.8%). The reason for the alarm was not identified in 5 patients (17.8%). No patients had an electrical issue with the pump or a driveline disruption identified. Conclusion Readmission due to low flow alarms is relatively common after HM3 LVAD. Hypovolemia was the most frequent etiology of low flow alarms. Obstruction of the inflow cannula or outflow graft is a serious complication that can present with low flow alarms and requires reoperation.