Heart Mate 3 Pump Thrombosis After Ventricular Tachycardia Ablation: Pushing the Boundaries of Hemocompatibility

Abstract

<h3>Introduction</h3> The risk for pump thrombosis (PT) following ventricular tachycardia (VT) ablation in HeartMate II and HeartWare HVAD left ventricular assist devices (LVADs) has been described previously; however, it is unknown whether Heart Mate 3 (HM3) LVADs are also at increased risk of PT following VT ablation. <h3>Case Report</h3> A 51-year-old male with non-ischemic cardiomyopathy status post HM3 LVAD as destination therapy, VT on mexiletine and quinidine with previous VT ablation, and amiodarone-induced thyrotoxicosis presented to the emergency room in VT storm after multiple defibrillator shocks. He underwent successful endocardial/epicardial VT ablation of seven VT morphologies, ethanol ablation of the coronary sinus branch, as well as coil embolization of two left circumflex branches that fed the culprit territory. Target ACT was achieved throughout the procedure and he was bridged to warfarin with a therapeutic INR upon discharge. Two weeks later, he presented with low flow LVAD alarms, a subtherapeutic INR, and an elevated lactate dehydrogenase concerning for PT. Despite volume resuscitation and pressors, he required initiation of venoarterial extracorporeal membrane oxygenation (VA-ECMO), intra-aortic balloon pump, and underwent a LV outflow tract aortogram. Thrombus was noted in the LVAD outflow graft and the LVAD flow was 0 liters per minute. Thrombolytics were not given due to the patient's tenuous status and need for emergent pump exchange, so decision was made to turn off the LVAD to prevent a cardioembolic event while he was supported by VA-ECMO. Transthoracic echocardiogram confirmed PT with a large thrombus extending out of the inflow cannula. The patient was deemed not to be a surgical candidate given a high operative mortality after worsening shock, liver failure, and bacteremia. His family proceeded with comfort care and support was withdrawn. <h3>Summary</h3> While PT is rare with HM3 LVADs even with lower intensity anticoagulation, there may be a higher risk of PT after VT ablation.