a plot of the log fold difference of the number of cycles to threshold versus that difference’s p-value.[figure1] Conclusions: Analysis of the inflammatory pathway transcriptome after continuous flow LVAD reveals a notable up-regulation of the same in- flammatory genes which were found to be significantly down-regulated prior to implant. This up-regulation suggests a shift towards “normaliza- tion” of the immune system after one month of LVAD support. 563 Lack of Sensitization in Patients Awaiting Heart Transplantation on Heartmate II Axial Flow Assist Devices M. Kwon, J. Moriguchi, M. Kittleson, J. Patel, M. Kawano, S. Davis, E. Reed, C. Burch, A. Velleca, E. Stimpson, A. Ardehali, J. Kobashigawa. David Geffen School of Medicine at UCLA/Cedars Sinai Heart Institute, Los Angeles, CA. Purpose: Patients awaiting heart transplantation on ventricular assist de- vice (VAD) support have been noted to be at increased risk for the development of circulating antibodies. This may be due to multiple blood transfusions and/or polyurethane lining of the VAD. Sensitization has also led to poor outcome after heart transplantation. The newer axial flow VADs have been approved as a bridge to heart transplant and reportedly have a lower tendency to develop circulating antibodies. We reviewed our insti- tutional experience with Heartmate II axial flow VADs in patients awaiting heart transplant for the development of circulating antibodies. Methods and Materials: Between 2008 and 2009, 15 patients awaiting heart transplantation were supported with Heartmate II axial flow VADs for a mean of 119 +/- 114 days. Patients on Heartmate II axial flow VADs were compared to patients on non-axial flow VADs (N=33) and a control group (N=123) of non-VAD patients awaiting heart transplant for the development of elevated circulating antibodies (PRA screen 10%). Results: 2/15 (13%) patients on Heartmate II axial flow VADs developed elevated circulating antibodies by comparison to 13/33 (39%) patients on non-axial flow VAD support (p=0.08) and 15/123 (12%) of control pa- tients (p=0.39). Outcome for those axial flow VAD patients after heart transplantation revealed comparable 30-day survival and first-year rejec- tion risk to the control group. Conclusions: Patients supported with axial flow VADs prior to heart trans- plantation are not at increased risk for the development of circulating antibod- ies. These findings suggest tha the risk of sensitization should not deter the use of VAD support in patients awaiting heart transplantation.[table1] 564 Trends in Body Mass Index Following Long Term Mechanical Circulatory Support Y. Ravi, A. Knapkie, S. Wissman, T. Yanssens, B. Sun, L. Louis, M. Firstenberg, B. Needleman, A. Hasan, C.B. Sai Sudhakar. The Ohio State University Medical Center, Columbus, OH. Purpose: Patients with extremes of body mass index (BMI) (18 and 32kg/m 2 ) are not candidates for heart transplantation (TX) and are considered for long term mechanical circulatory support as destination therapy (DT). Correction of BMI could potentially make them transplant eligible. Trend in BMI following long term mechanical circulatory support devices (MCSD) is unknown. We present our experience regarding serial BMI evaluations of patients on MCSD. Methods and Materials: Between 2005 and 2009, 74 patients received MCSD either as DT or as a bridge to TX. BMI was obtained every 3 months. Follow-up was for one year. Patients were divided into groups based on the International classification of adult underweight (BMI 18.5), normal (18.5-24.99), overweight (25-29.9) and increasing classes of obesity (30). Variation in BMI was calculated as a percentage gain or loss in comparison to the baseline BMI. Results: Following MCSD, the underweight group (n=3) increased their BMI to 120.1  7.4% of their baseline at 12 months. Initially, at 3 months, the BMI decreased in the normal weight group (n=22) to 96.2110.02% and at 1 year to 103.613.4% of their baseline. In contrast, BMI decreased in higher classes of obesity (n=6) (BMI 35-40) at 3 months (94.710.08% of baseline). No further significant decrease was observed at 6 and 12 months.[figure1]Following gastric sleeve resection, BMI de- creased sufficiently in one patient to enable listing for TX. Conclusions: Our results indicate BMI increases in underweight patients following implantation of MCSD and would enable them to be listed for TX if other criteria are met. It is clear that obese and overweight patients may need aggressive forms of weight reduction (eg. surgical correction of obesity) prior to being considered for TX. 565 Less Invasive Surgery with Circulite® Synergy® Pocket Micro-Pump Reduces Adverse Events Verses Traditional VADs B. Meyns, 1 F. Rega, 1 A. Simon, 2 S. Klotz, 3 C. Schlensak, 4 T. Wittwer, 5 D. Burkhoff. 6,7 1 Gasthuisberg University Hospital, Leuven, Belgium; 2 Hannover Medical School, Hannover, Germany; 3 University Hospital, Muenster, Germany; 4 University Medical Center, Freiburg, Germany; 5 University Hospital of Cologne, Cologne, Germany; 6 Columbia University, New York, NY; 7 CircuLite, Inc., Saddle Brook, NJ. Purpose: Use of assist devices is generally limited to end-stage patients due to the associated risks. Expansion of device use to a broader range of sick patients requires less invasive devices with fewer complications. Methods and Materials: The Synergy Micro-pump is a miniature pump implanted subcutaneously in a pacemaker-like pocket in an 90-minute Heartmate II Non-Axial Flow Control N 15 33 123 Transplanted 6 17 66 1-Year Survival 100% 100% 92% 1-Year Actuarial Freedom from Any-Treated Rejection 100% 67% 94% P=NS in all groups S183 Abstracts