title: Increasing Frequency of Left Ventricular Assist Device Exchanges in the United States.
abstract: BACKGROUND
  Recent reports indicate an increased prevalence and earlier onset of pump thrombosis and associated pump exchanges after left ventricular assist device (LVAD) implantation. Questions remain regarding the current rate and clinical effect of pump exchanges.
  
  
  METHODS
  All United States Medicare fee-for-service patients undergoing LVAD implantations (n = 3,166) between January 2009 and December 2012 were identified by procedural codes present on carrier claims collected by the Centers for Medicare & Medicaid Services. Pump exchange, pump removal, heart transplantation, and death were collected from subsequent carrier claim and denominator files. Comorbidities present before implantation were generated using the Elixhauser comorbidity index.
  
  
  RESULTS
  Compared with patients who received LVADs before March 1, 2011, LVAD recipients after March 1, 2011, were older on average (63.9 vs 62.2 years, p < 0.01), more likely to be male (82.3% vs. 79.4%, p = 0.04), and had a higher incidence of common comorbidities. The later cohort had higher occurrence of pump exchange by Kaplan-Meier time-to-event estimates and Fisher exact tests at 3 months (1.8 vs 0.8, p = 0.02), 6 months (3.3 vs 1.0, p < 0.01), and 12 months (4.9 vs 2.2, p < 0.01). Cox regression analysis found time-dependent pump exchange was associated with worse survival (hazard ratio, 2.5; 95% confidence interval, 1.8 to 3.62; p < 0.01) after adjusting for age, gender, and comorbidities.
  
  
  CONCLUSIONS
  Although LVAD exchanges remain relatively uncommon, a significant increase in the incidence of the procedure has occurred since March 1, 2011. Pump exchanges are highly associated with death, and further research is required to understand the cause of this disturbing trend and surveillance to determine its trajectory.
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Fenton H
authors.initials: FH
authors.lastname: McCarthy
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Dale
authors.initials: D
authors.lastname: Kobrin
authors.affiliation: Division of Cardiovascular Medicine, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: J Eduardo
authors.initials: JE
authors.lastname: Rame
authors.affiliation: Department of Medicine, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Groeneveld
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: McDermott
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Pavan
authors.initials: P
authors.lastname: Atluri
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Acker
authors.affiliation: Division of Cardiovascular Surgery, University of Pennsylvania Health System, Philadelphia, Pennsylvania. Electronic address: nimesh.desai@uphs.upenn.edu.
authors.forename: Nimesh D
authors.initials: ND
authors.lastname: Desai
mesh_terms: D000368:Aged; D020878:Device Removal / Q000191:economics / Q000706:statistics & numerical data*; D018588:Fee-for-Service Plans / Q000191:economics*; D005260:Female; D006333:Heart Failure / Q000401:mortality / Q000628:therapy*; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics*; D008875:Middle Aged; D011379:Prognosis; D011475:Prosthesis Failure; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D014481:United States / Q000453:epidemiology