Abstracts event was 79 and 20 days for hemolysis, 286 and 321 days for TIA/ embolic stroke, and 579 and 579 days for PTE. Conclusions: Power spikes are a common occurrence in patients with Heartmate II LVADs. They occur frequently in the first year after implantation but their initial presentation can be more than three years later. They do not frequently precede clinical events suggestive of pump thrombosis and their proximity to the clinical event varies. 173 HAS-BLED and CHA2DS2-VASc Scores as Predictors of Bleeding and Thrombotic Risk after HeartMate II Ventricular Assist Device Implantation R.J. Koene, S.N. Adatya, N. Naksuk, A.N. Rosenbaum, R. John, P.M. Eckman. Department of Medicine - Cardiovascular Division, University of Minnesota, Minneapolis, MN. Purpose: Bleeding and thromboembolic (TE) events are feared complications following continuous-flow ventricular assist device (CF-VAD) implant. Risk stratification may guide individualization of care and improve outcomes. The HAS-BLED scoring system has been shown to predict bleeding events in patients on chronic anticoagulation, while the CHA2DS2-VASc score has been shown to quantify stroke risk in patients with atrial fibrillation. We hypothesized that these widely used scores would be predictive of bleeding and TE complications after CF-VADs. Methods and Materials: HAS-BLED and CHA2DS2-VASc scores were determined retrospectively for 171 consecutive patients who received HeartMate II (HMII) CF-VAD at a single center between 6/20/05 and 9/15/11. We excluded events occurring within 1 week and deaths occurring within 30 days of implant. Bleeding was defined as any systemic bleeding that required hospital admission or blood transfusion. TE events included ischemic stroke, transient ischemic attack, systemic emboli, or pump thrombosis. S71 Results: We observed 28 bleeding (16.3%) and 13 TE (7.6%) events in follow-up. The mean (⫾SD) HAS-BLED score was 2.1⫾1.0 vs 1.6⫾0.7 (p¼0.01) in patients with bleeding versus those without, respectively. The mean (⫾SD) CHA2DS2-VASc scores were 3.4⫾1.2 vs 2.6⫾1.2 (p¼0.03) in patients with TE events versus those without, respectively. HAS-BLED score Z 3 had a significantly higher risk for bleeding events compared to a score o 3 (43% vs 13%, p¼0.01). CHA2DS2-VASc score Z 3 had a higher risk for thrombotic event compared to a score o 3 (12% vs 4%, p¼0.04). Conclusions: A HAS-BLED or CHA2DS2-VASc score of 3 or more conferred significantly higher risks of bleeding or TE, respectively, following HMII implant. These scores may help clinicians construct individualized anticoagulation regimens for this high-risk group. 174 Platelet GPIb Ectodomain Shedding – A New Biomarker for GI Bleeding in Continuous Flow VAD Recipients? T.A. Snyder,1 J. Skaugen,1 K.E. Nelson,1 D.A. Horstmanshof,1 D.W. Schmidtke,2 J.W. Long.1 1Intregis Advanced Cardiac Care, Integris Baptist Medical Center, Oklahoma City, OK; 2School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK. Purpose: Gastroinstestinal bleeding (GIB) occurs in 30% of continuous flow ventricular assist device (CFVAD) patients. Given that nearly all CFVAD recipients demonstrate a loss of large von Willebrand Factor (vWF) multimers, we sought to examine other factors that can contribute to the risk of GIB events. Methods and Materials: Blood samples were obtained on all inpatient days or at outpatient clinic visits from 34 patients receiving Thoratec HeartMate II (25), WorldHeart Levacor (6), or Syncardia temporary Total Artifical Heart (TAH; 3) blood pumping systems. Assays were performed to quantify plasma levels of glycocalicin (the platelet GPIb (vWF receptor) ectodomain), platelet microparticle coagulation activity, thrombin anti-thrombin, Coagulation Factor XII, thromboxane B2. Statistcal analyses were performed using Stastica (Statsoft) to examine assay levels prior to, during, and after confirmed bleeding, thromboembolic (TE), and infectious events, and risk factors based on patient demographics and co-morbidities for adverse events. Results: Plasma glycocalin was observed to be elevated compared to preoperative values in all HeartMate II, TAH, and 3 of the Levacor recipients and in older recipients. A glycocalin value above 4 mg/mL (normal range 0-2 mg/mL) was 92% predictive of a bleeding event. A failure of the glycocalin level to decrease below 2.5 mg/mL or an increase following a bleeding event was 97% predictive of a subsequent bleeding event. There was not a consistent signal which could be determied to predict TE or infectious events with greater than 50% accuracy. Conclusions: GIB remains a significant complication of CFVAD support and predicting which patients are at highest risk for GIB events. Glycocalin may be a biomarker to indicate patients at risk for GIB and particularly re-occurent GIB events. The mechanism causing an elevation in platelet GPIb shedding (plasma glycocalicin) deserves further investigation as a potential avenue to elucidate the mechanisms contributing to GIB bleeding risk. 175 Comparative Analysis of von Willebrand Disease in Patients with Mechanical Circulatory Pulsatile and Non-Pulsatile Support C. Oezpeker, B. Bohms, D. Roefe, J. Boergermann, S. Ensminger, J. Gummert, H. Milting. Clinic of Thoracic and Cardiovascular Surgery, Erich & Hanna Klessmann-Institute, Ruhr-University Bochum, Heart & Diabetescenter NRW, Bad Oeynhausen, Germany. Purpose: Aquired von Willebrand (vW) disease is induced by continuous flow ventricular assist devices (VAD) in patients under mechanical circulatory support (MCS). However, the influence of different MCS on the degradation of high molecular weight vW aggregates is less investigated. In addition the influence of intensive care therapy on vW-multimere analysis before MCS is not known.