title: Treatment of device thrombus in the HeartWare HVAD: Success and outcomes depend significantly on the initial treatment strategy.
abstract: BACKGROUND
  Pump thrombosis is a major adverse event in patients supported with a left ventricular assist device (LVAD). Treatment approaches include device exchange, lytic therapy, or augmentation of anticoagulation or antiplatelet therapy. The optimal strategy in the HeartWare HVAD Ventricular Assist System (HeartWare, Framingham, MA) is uncertain, and because few large studies have examined differing treatment outcomes, we have reviewed findings from the Mechanical Circulatory Support Research Network registry.
  
  
  METHODS
  Between March 2009 and August 2014, 175 patients (133 male) underwent implantation of the HeartWare HVAD at institutions that comprise the Mechanical Circulatory Support Research Network. Median age at implant was 59 years (range, 18-76 years). Follow-up was available in all patients for a median of 6 months (maximum, 61 months) and for a total of 163 patient-years of support. There were 36 pump thromboses (using Interagency Registry for Mechanically Assisted Circulatory Support criteria) in 21 patients for a total event rate of 0.22 events/patient-year of support; 13 patients had 1 event, 4 had 2, 2 had 3, 1 had 4, and 1 had 5. The median time to the first thrombosis was 6.4 months, and to each subsequent thrombosis was 4, 3, 2, and 2 months, respectively. Primary treatment success was defined as the patient remaining alive and within the first 30 days of the initial treatment be free from stroke, recurrence of pump thrombosis, device exchange, or urgent transplantation (United Network of Organ Sharing Status 1A). Medical treatment was defined as tissue plasminogen activator, heparin plus glycoprotein IIb/IIIa inhibitor, or heparin alone, not followed by surgical treatment within 72 hours.
  
  
  RESULTS
  Initial medical treatment was used in 29 episodes (tissue plasminogen activator in 24, heparin alone in 4, and heparin plus glycoprotein IIb/IIIa in 1) and surgical (device exchange) in 7. Medical treatment was successful in 14 of 29 episodes (48%). Complications of medical treatment included hemorrhagic stroke in 6 patients (21%), need for urgent device exchange/transplant in 6 (21%), and death in 3 (10%). Surgical treatment was successful in all 7 patients (100%). No significant early complications or early deaths occurred after device exchange.
  
  
  CONCLUSIONS
  In this large multicenter analysis, we observed that medical therapy, as the initial treatment strategy for HeartWare HVAD thrombosis, is associated with low success (48%) and a significant risk of hemorrhagic stroke (21%) and death (10%). However, initial treatment with device exchange was uniformly successful and not associated with significant early morbidity or death. Although the optimal treatment approach for HeartWare HVAD pump thrombosis remains undecided, these data do not support the routine use of medical therapy as an initial treatment strategy.
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota. Electronic address: stulak.john@mayo.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Stulak
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Dunlay
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Shashank
authors.initials: S
authors.lastname: Sharma
authors.affiliation: University of Vanderbilt, Vanderbilt Heart and Vascular Center, Nashville, Tennessee.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Haglund
authors.affiliation: University of Vanderbilt, Vanderbilt Heart and Vascular Center, Nashville, Tennessee.
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Davis
authors.affiliation: Division of Cardiovascular Diseases, St. Vincent's Hospital, Indianapolis, Indiana.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cowger
authors.affiliation: Inova Fairfax Hospital, Inova Heart and Vascular Institute, Falls Church, Virginia.
authors.forename: Palak
authors.initials: P
authors.lastname: Shah
authors.affiliation: Department of Cardiac Surgery, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Faraz
authors.initials: F
authors.lastname: Masood
authors.affiliation: Department of Cardiac Surgery, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Keith D
authors.initials: KD
authors.lastname: Aaronson
authors.affiliation: Department of Cardiac Surgery, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pagani
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Simon
authors.initials: S
authors.lastname: Maltais
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology* / Q000628:therapy*; D012074:Remission Induction; D012189:Retrospective Studies; D013927:Thrombosis / Q000209:etiology* / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult
keywords: HeartWare; anti-coagulation; device exchange; lytic therapy; pump thrombosis; thrombus; ventricular assist device