title: Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) analysis of pump thrombosis in the HeartMate II left ventricular assist device.
abstract: BACKGROUND
  Pump thrombosis remains an uncommon but potentially catastrophic complication of durable continuous-flow left ventricular assist devices (LVAD). A perceived increase in the incidence of pump thrombosis in the HeartMate II (HMII) LVAD (Thoratec, Pleasanton, CA) by clinicians prompted this analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) database.
  
  
  METHODS
  Between 2006 and June 2013, 8,988 United States patients aged older than 18 years received a durable LVAD. Of these, 6,910 adult patients from 132 institutions who received a HMII LVAD were entered in the INTERMACS database and constitute the study group for this analysis.
  
  
  RESULTS
  Overall survival (with censoring at transplant or explant for recovery) with the HMII LVAD was 80% at 1 year and 69% at 2 years and was not significantly different when stratified by era of implant. Freedom from device exchange or death due to thrombosis decreased from 99% at 6 months in 2009 to 94% in 2012 (p < 0.0001). Multivariable hazard function analysis showed risk factors for pump thrombosis included later implant year (p < 0.0001), younger age (p < 0.0001), higher creatinine (p = 0.002), larger body mass index (p = 0.004), white race (p = 0.0004), left ventricular ejection fraction above 20% (p = 0.02), and higher lactate dehydrogenase level at 1 month (p < 0.0001). Survival (p < 0.0001) and freedom from infection (p = 0.008) and cerebrovascular accident (p < 0.0001) were lower after pump exchange than after primary implant.
  
  
  CONCLUSIONS
  Pump exchange or death due to pump thrombosis increased during 2011 and 2012, but the magnitude of the increase remained relatively small. Survival remains high (80% at 1 year) with the HMII LVAD. Risk factor analysis suggests that a number of patient-related factors contribute to the risk of thrombosis. Markedly elevated lactate dehydrogenase in the first month is a predictor of pump thrombosis. This analysis could not examine the potential role of technical factors during implant, such as sub-optimal pump or graft positioning, changes in patient management paradigms with pump speed settings, improved recognition and change in the threshold for pump exchange, or design or production changes with the pump, as contributors to the risk of pump thrombosis.
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama. Electronic address: jkirklin@uab.edu.
authors.forename: James K
authors.initials: JK
authors.lastname: Kirklin
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: David C
authors.initials: DC
authors.lastname: Naftel
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Kormos
authors.affiliation: University of Michigan, Ann Arbor, Michigan.
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pagani
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Myers
authors.affiliation: Cardiovascular Division of Brigham & Women's Hospital, Boston, Massachusetts.
authors.forename: Lynne W
authors.initials: LW
authors.lastname: Stevenson
authors.affiliation: University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Acker
authors.affiliation: Montfiore Medical Center, Bronx, New York.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Goldstein
authors.affiliation: Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Silvestry
authors.affiliation: Duke University, Durham, North Carolina.
authors.forename: Carmelo A
authors.initials: CA
authors.lastname: Milano
authors.affiliation: National Heart, Lung, and Blood Institute, Bethesda, Maryland.
authors.forename: J T
authors.initials: JT
authors.lastname: Baldwin
authors.affiliation: National Heart, Lung, and Blood Institute, Bethesda, Maryland.
authors.forename: J
authors.initials: J
authors.lastname: Timothy Baldwin
authors.affiliation: Mount Sinai Medical Center, New York, New York.
authors.forename: Sean
authors.initials: S
authors.lastname: Pinney
authors.affiliation: University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: J
authors.initials: J
authors.lastname: Eduardo Rame
authors.affiliation: National Heart, Lung, and Blood Institute, Bethesda, Maryland.
authors.forename: Marissa A
authors.initials: MA
authors.lastname: Miller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015331:Cohort Studies; D004868:Equipment Failure / Q000706:statistics & numerical data*; D005260:Female; D006333:Heart Failure / Q000628:therapy*; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D012042:Registries; D012189:Retrospective Studies; D015996:Survival Rate; D013927:Thrombosis / Q000453:epidemiology* / Q000401:mortality; D014481:United States / Q000453:epidemiology; D018487:Ventricular Dysfunction, Left / Q000628:therapy*
chemical_list: D015415:Biomarkers; D007770:L-Lactate Dehydrogenase
keywords: HeartMate II; INTERMACS; LVAD; heart failure; pump thrombosis