title: Association between cell-derived microparticles and adverse events in patients with nonpulsatile left ventricular assist devices.
abstract: BACKGROUND
  Continuous-flow left ventricular assist devices (LVADs) expose blood cells to high shear stress, potentially resulting in the production of microparticles that express phosphatidylserine (PS+) and promote coagulation and inflammation. In this prospective study, we attempted to determine whether PS+ microparticle levels correlate with clinical outcomes in LVAD-supported patients.
  
  
  METHODS
  We enrolled 20 patients undergoing implantation of the HeartMate II LVAD (Thoratec Corp, Pleasanton, CA) and 10 healthy controls who provided reference values for the microparticle assays. Plasma was collected before LVAD implantation, at discharge, at the 3-month follow-up, and when an adverse clinical event occurred. We quantified PS+ microparticles in the plasma using flow cytometry.
  
  
  RESULTS
  During the study period, 8 patients developed adverse clinical events: ventricular tachycardia storm in 1, non-ST-elevation myocardial infarction in 2, arterial thrombosis in 2, gastrointestinal bleeding in 2, and stroke in 3. Levels of PS+ microparticles were higher in patients at baseline than in healthy controls (2.11% ± 1.26% vs 0.69% ± 0.46%, p = 0.007). After LVAD implantation, patient PS+ microparticle levels increased to 2.39% ± 1.22% at discharge and then leveled to 1.97% ± 1.25% at the 3-month follow-up. Importantly, levels of PS+ microparticles were significantly higher in patients who developed an adverse event than in patients with no events (3.82% ± 1.17% vs 1.57% ± 0.59%, p < 0.001), even though the 2 patient groups did not markedly differ in other clinical and hematologic parameters.
  
  
  CONCLUSIONS
  Our results suggest that an elevation of PS+ microparticle levels may be associated with adverse clinical events. Thus, measuring PS+ microparticle levels in LVAD-supported patients may help identify patients at increased risk for adverse events.
authors.affiliation: Departments of Cardiology, Texas Heart Institute, Houston, Texas.
authors.forename: Angelo
authors.initials: A
authors.lastname: Nascimbene
authors.affiliation: Departments of Cardiovascular Surgery, Texas Heart Institute, Houston, Texas.
authors.forename: Ruben
authors.initials: R
authors.lastname: Hernandez
authors.affiliation: Departments of Cardiology, Texas Heart Institute, Houston, Texas.
authors.forename: Joggy K
authors.initials: JK
authors.lastname: George
authors.affiliation: Departments of Cardiovascular Surgery, Texas Heart Institute, Houston, Texas.
authors.forename: Anita
authors.initials: A
authors.lastname: Parker
authors.affiliation: Division of Thrombosis Research, Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Bergeron
authors.affiliation: Division of Thrombosis Research, Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: Subhashree
authors.initials: S
authors.lastname: Pradhan
authors.affiliation: Division of Thrombosis Research, Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors.forename: K Vinod
authors.initials: KV
authors.lastname: Vijayan
authors.affiliation: Departments of Cardiology, Texas Heart Institute, Houston, Texas.
authors.forename: Andrew
authors.initials: A
authors.lastname: Civitello
authors.affiliation: Departments of Cardiology, Texas Heart Institute, Houston, Texas.
authors.forename: Leo
authors.initials: L
authors.lastname: Simpson
authors.affiliation: Puget Sound Blood Center, Seattle, Washington.
authors.forename: Maria
authors.initials: M
authors.lastname: Nawrot
authors.affiliation: Division of Biostatistics and Epidemiology, Texas Heart Institute, Houston, Texas.
authors.forename: Vei-Vei
authors.initials: VV
authors.lastname: Lee
authors.affiliation: Departments of Cardiovascular Surgery, Texas Heart Institute, Houston, Texas.
authors.forename: Hari R
authors.initials: HR
authors.lastname: Mallidi
authors.affiliation: Departments of Cardiology, Texas Heart Institute, Houston, Texas.
authors.forename: Reynolds M
authors.initials: RM
authors.lastname: Delgado
authors.affiliation: Puget Sound Blood Center, Seattle, Washington; Hematology Division, Department of Medicine, School of Medicine, University of Washington, Seattle, Washington.
authors.forename: Jing Fei
authors.initials: JF
authors.lastname: Dong
authors.affiliation: Departments of Cardiovascular Surgery, Texas Heart Institute, Houston, Texas. Electronic address: lschwenke@texasheart.org.
authors.forename: O H
authors.initials: OH
authors.lastname: Frazier
mesh_terms: D055252:Cell-Derived Microparticles; D005434:Flow Cytometry; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000628:therapy*; D016027:Heart Transplantation; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006801:Humans; D010865:Pilot Projects; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: cell-derived microparticles; phosphatidylserine; ventricular assist device