245: Allomap Use in Cardiac Transplantation: Single Center Experience

Abstracts 242 Pre-B-Cell Colony Enhancing Factor (PBEF) Is a Novel target in Hypoxia-Induced Murine Pulmonary Hypertension R.F. Machado, L. Moreno-Vinasco, R. Zaidi, S. Sammani, J.G.N. Garcia. 1University of Chicago, Chicago, IL; 2, Chicago, IL; 3, Chicago, IL. Purpose: Pulmonary arterial hypertension (PAH) is characterized by significant and aberrant cellular proliferation of the endothelium and smooth muscle that results in an angioproliferative vasculopathy with complex involvement of apoptosis and inflammatory pathways. We previously demonstrated Pre-B-Cell Colony Enhancing Factor (PBEF) to be a biomarker and candidate gene in inflammatory lung injury (Ye S et al 2005; Hong et al 2008), with extracellular proinflammatory cytokine-like, NF-kB-mediated activity as well as intracellular enzymatic activity as a phosphoribosyltransferase which regulates intracellular NAD levels (NAMPT activity) and inhibits apoptosis. Thus, we hypothesize that PBEF might be a potential therapeutic target in PAH. Methods and Materials: We utilized a murine model of pulmonary hypertension with chronic hypoxia and VEGFR2 blockade with SU5416 for 3 weeks in PBEF heterozygous mice PBEF⫹/⫺ and wild type controls. Hemodynamic assessment was performed at day 21. Results: Our preliminary results indicated that in wild type (WT) mice, hypoxia/SU developed pulmonary artery remodeling induced significant increases (*P⬍0.05) in mean pulmonary arterial pressure (PPA, mean ⫽19.6 mmHg), right ventricular pressures (RVSP, mean⫽ 19 mmHg), right ventricular hypertrophy and hematocrit (mean⫽39%) when compared to normoxic WT mice. In contrast, PBEF⫹/⫺ mice had significant decreases in RSVP (40% decrease), in PPA pressures (25% decrease), right ventricular hypertrophy (20% decrease) and in hematocrit (15% decrease) (**P⬍0.05) when compared to hypoxia-SU injured WT mice. Conclusions: Our results implicate PBEF as a novel target involved in PAH pathophysiology with therapeutic implications. Future mechanistic studies will discern between the pro-inflammatory and anti-apoptosis contribution of PBEF to PAH development.

243 Impact of Mechanical Unloading on Myocardial Endothelium and Microvasculature S. Drakos,1,2,3,4 E. Hammond,2,3 S. Clayson,1,3 M.P. Revelo,2,3 S. Stoker,1,3 A. McCormick,1,3 H. Smith,1,3 C. Selzman,2,3 D.R. Verma,1,2,3 D. Budge,1,3 J. Stehlik,2,3 D. Li,2 A. Kfoury.1,2,3 1Utah Artificial Heart Program, Intermountain Medical Center, Salt Lake City, UT; 2Universitty of Utah, Salt Lake City, UT; 3UTAH Cardiac Transplant Program, Salt Lake City, UT; 43rd Cardiology Department, University of Athens, Athens, Greece. Purpose: Decreased microvascular density is a well described feature of cardiac remodeling. Left ventricular assist device (LVAD) unloading has been associated with favorable changes on cardiac remodeling. However, its effect on endothelium and myocardial microvasculature, the topic of interest in this study, is unknown. Methods and Materials: Left ventricular tissue samples and right heart catheterization data were collected from patients suffering from chronic (n⫽15) and acute (n⫽8) heart failure (HF) during LVAD implant and explant. Eight normal donor hearts were also analyzed. New advances in digital microscopy provide a unique opportunity for comprehensive endocardium-to-epicardium examination of heart tissue. Microvascular evaluation was quantitatively performed with a whole-field digital histopathology system after the tissue was immunohistochemically stained for the endothelial cell protein CD-34. Electron microscopy for ultrastructural evaluation was also done. Results: Hemodynamic data revealed significant degree of pressure unloading post LVAD. Microvascular density was found to be significantly decreased in the failing hearts compared to the normal donor

S83 hearts and it significantly increased post LVAD unloading by 33% (p⫽0.001). The average microvessel lumen area significantly decreased post LVAD unloading by 36% (p⫽0.027). These findings were consistent in both the chronic and acute HF study populations. In agreement with these data, we identified post LVAD unloading ultrastructural evidence of endothelial cell activation These changes included basal lamina reduplication, increased nuclei and cytoplasmic size protruding into the capillary lumen accompanied by increase in luminal cytoplasmic processes and numerous irregular surface membrane projections. Conclusions: LVAD-induced unloading of the failing human heart caused increased microvascular density associated with evidence of endothelial cell activation. These findings provide new insight that may guide future studies warranted to further investigate the effects of mechanical unloading on cardiac remodeling.

244 Effect of Mechanical Unloading on Fibrosis and Hypertrophy during Cardiac Remodeling in Humans S. Drakos,1,2,3 E. Hammond,2,3 B. Reid,1,2,3 S. Stoker,1,3 M.P. Revelo,2,3 B. Rasmusson,1,3 C. Selzman,2,3 R. Alharethi,1,3 A. McCormick,1,2 E. Gilbert,2,3 D. Miller,3 D. Li,2 A. Kfoury.1,2,3 1Utah Artificial Heart Program, Salt Lake City, UT; 2University of Utah, Salt Lake City, UT; 3 UTAH Cardiac Transplant Program, Salt Lake City, UT. Purpose: Left ventricular assist device (LVAD) unloading has been associated with positive changes on cardiac remodeling. Cardiac fibrosis a hallmark of remodeling, has been pathophysiologically linked to cardiomyocyte hypertrophy (HPT). Yet, the impact of LVAD unloading on fibrosis and the degree of HPT regression possibly to the point of atrophy is controversial. Methods and Materials: Left ventricular tissue samples and right heart catheterization data were collected from patients with chronic (n⫽15) and acute (n⫽8) heart failure (HF) during LVAD implant and explant at the time of transplant. Eight normal donor hearts were also analyzed. Histochemical stains for cardiomyocyte size, collagen and glycogen content assessment were performed. Whole-field digital microscopy allowed complete epicardium-to-endocardium quantitative inspection of the heart tissue. Electron microscopy for ultrastructural evaluation was also done. Results: Hemodynamic data revealed significant degree of pressure unloading post LVAD. Interstitial and total collagen content were significantly increased in the failing compared to normal donor hearts and they further significantly increased post LVAD unloading by 61% (p⫽0.001) and 35% (p⫽0.001). Cardiomyocyte size decreased post LVAD unloading by 20.5% (p⫽0.027), but not beyond that of normal donor hearts. Further, ultrastructural evidence suggestive of HPT regression to the point of cardiomyocyte degeneration and atrophy was not seen. In agreement with these findings, cardiomyocyte glycogen content was unchanged post LVAD unloading. These findings were consistent in both chronic and acute HF groups and in patients with prolonged (⬎12weeks) duration of mechanical circulatory support. Conclusions: LVAD-induced unloading of the failing human heart caused increased fibrosis but interestingly without structural ultrastructural or metabolic changes consistent with cardiomyocyte degeneration and atrophy. These findings may be useful in guiding future studies warranted to further investigate the effects of mechanical unloading on cardiac remodeling.

245 Allomap Use in Cardiac Transplantation: Single Center Experience I. Dumitru,1 S. Radio,2 D. Tayama.3 1UNMC, Omaha, NE; 2UNMC, Omaha, NE; 3XDX, Brisbane, CA. Purpose: Allomap can be safely used in monitoring for ACR while aggressively weaning patients off steroids and minimizing immunosuppres-

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The Journal of Heart and Lung Transplantation, Vol 29, No 2S, February 2010

sion levels, in conjunction with clinical and echocardiographic (TTE)assessment, therefore minimizing biopsy cardiac allograft evaluation, complications and cost for patients. Methods and Materials: 51 patients had surveillance for ACR using allomap in 2008 for a total of 98 results. 55 patients had surveillance for ACR using allomap in 2009 for a total of 90 results. All the patients in whom allomap was used were more than 2 months post transplant, on 20 mg daily of prednisone or less, have not received any blood transfusion or had any episode of documented ACR ISHLT grade ⬎⫽ 2R/3A within 30 days. Results: In 2008 there were a total of 9 allomap scores above the threshold of 34. Follow up biopsy per protocol confirmed ⬎⫽ 2R/3A rejection in 2 cases (20%), requiring treatment. In 2009 there were 4 allomap scores above the threshold of 34 and all follow up biopsies were ⬍grade 2R/3A rejection. Patients with an allomap score ⬍34 and normal graft function by TTE had no incidence of ACR. 173 biopsies were performed in 2008 and 99 biopsies were performed in 2009. Allomap resulted in a 42.7% reduction of surveillance biopsies. Patients satisfaction significantly increased. There was a $ 5,000 cost saving per patient receiving allomap testing ($7,200) when compared with patient receiving biopsy ($ 12,000) in our center, for a total $370,000 patient cost savings. Conclusions: 1. Allomap is a safe non-invasive test in assessing risk of ACR in conjunction with clincial and TTE assessment in cardiac transplant patients being weaned off steroids. 2. Patients with allomap ⬍34 and normal clinical and graft assessment by TTE had no evidence of ACR. 3. Allomap scores ⬎⫽34 were associated with significant ACR by biopsy ISHLT grade 2R/3A rejection in 2/13 cases over a 2 year period and accompanied by clinical and echocardiographic evidence of rejection. 4. Allomap use resulted in a 42.7% decrease in biopsies and in a net $5,000 cost saving per patient.

246 Switch to Sirolimus and Dose Reduced Calcineurin-Inhibitor after Cardiac Transplantation Is Safe and Results in Renal Stability over the Ensuing Three Years S. Khandhar,1 H. Shah,1 M. Shullo,2 C. Newman,3 M. Rebel,3 C. Yost,3 R. Zomak,3 D. McNamara,1 R. Kormos,3 Y. Toyoda,3 J. Teuteberg.1 1 University of Pittsburgh Medical Center, Pittsburgh, PA; 2University of Pittsburgh Medical Center, Pittsburgh, PA; 3University of Pittsburgh Medical Center, Pittsburgh, PA. Purpose: Sirolimus in addition to dose-reduced calcineurin inhibitors (CNI) and in place of cell cycle inhibitors (CCI) after cardiac transplantation (TX) can be used in the setting of vasculopathy, renal insufficiency, and recurrent rejection. The safety and renal benefits of such a change have not been well described. Methods and Materials: Tx patients at a single center from 1/1988 to 12/2008 started on sirolimus in place of CCI and had dose reduction of their CNI were compared to controls on full dose CNI and CCI. Controls were ⬎1 year post Tx and group matched by age, sex and creatinine. Minimum duration of sirolimus 30 days. Results: There were a total of 155 pts(79 sirolimus, 76 controls). There were no differences in recipient: age 51.9 yrs, 70% male, 88% white, CMV mismatch 19%, VAD 29%, induction 13% or tacrolimus 81%. Only difference was sirolimus group had fewer patients transplanted for ischemic cardiomyopathy (31% v 57% p⫽0.001). No differences in donor: age 32.1 yrs, 70% male, 86% white, and ischemic time 194 min. Indication for siroliumus: renal insufficiency 34%, vasculopathy 29%, recurrent rejection 19% and other 18%. Sirolimus was started 1429⫾1424 days after TX, mean duration of 1323⫾829 days. Freedom from significant rejection, defined as ISHLT ⬎⫽ 2R/3A (SR), in patients not switched for rejection was no different between groups(siroliumus 88% v controls 92% p⫽0.72). CrCl at baseline and during 3 years of follow-up did not differ between groups.[figure1]

Conclusions: Switch to sirolimus and a dose-reduced CNI can be performed without additional risk of SR. There is no difference in renal function over the following 3 years in comparison to group-matched controls.

247 Relationship between Microvascular and Macrovascular Disease in Heart Transplant Recipients M.S. Abu-Qaoud,1 D. Chen,2 J. Kerstetter,3 L.N. Stoletniy,2 R.G. Pai.2 1 Loma Linda University Medical Center, Loma Linda, CA; 2Loma Linda University Medical Center, Loma Linda, CA; 3Loma Linda University Medical Center, Loma Linda, CA. Purpose: Coronary macrovascular disease as demonstrated by coronary angiography or intravascular ultrasound (IVUS) is related to long-term survival in heart transplant recipients, and there is evidence that coronary microvascular disease (MVD) on endomyocardial biopsies is prognostically important as well. However, the relationship between these in transplant patients and the determinants of MVD are not known. Methods and Materials: We reviewed the simultaneously obtained endomyocardial biopsies and IVUS images of the coronary arteries in 33 heart transplant recipients. MVD was classified by light microscopy into 4 grades based on endothelial cell layer and vascular wall thickening. Macrovascular disease was evaluated from IVUS studies and assigned into one of 5 grades based on the Stanford classification. MVD and macrovascular disease were compared. Results: Patient characteristics: age at transplant 26⫾18 years, 67% men, average time post transplant to study 4 years. Concomitant medications: statins 68%, ACEI 49%, calcium channel blockers (CCB) 68%, Tacrolimus 59%, Sirolimus 35%, Mycophenolate 62%, prednisone 38%. Biopsy results for MVD: normal 6%, nonstenotic wall thickening 12%, both endothelial layer thickening and stenotic wall thickening 45%, and stenotic wall thickening with a normal endothelial layer 36%. IVUS analysis revealed grade 3 changes in 21% and grade 4 changes in 6%. There was no significant correlation between grades of micro and macrovascular disease (p⫽0.10). There were higher grades of MVD compared to macrovascular changes. MVD correlated positively with donor age (p⫽0.06) and treatment with tacrolimus (p⫽0.02) and a statin (p⫽0.05) but not with recipient age, gender, diabetes or treatment with ACEI, CCB, mycophenolate, or prednisone. Conclusions: 1) There is a poor relationship between coronary micro and macrovascular disease in patients with cardiac transplants, likely indicating divergent pathogenetic mechanisms. 2) MVD increases with donor age. 3) There is an intriguing relationship between MVD and treatment with statin and tacrolimus.

248 The Important Role of Immune Responses to Self-Antigens in Pathogenesis of Coronary Artery Vasculopathy Following Human Cardiac Transplantation D.S. Nath, H. Ilias Basha, D. Saini, S. Ramachandran, G.A. Ewald, N. Moazami, T. Mohanakumar. Washington University, Saint Louis. Purpose: We tested hypothesis that humoral immune responses to cardiac self antigens develop following human adult cardiac transplantation (HTx) and defined mechanisms for abrogation of peripheral self tolerance.