CONCLUSION Our pathology review showed a high prevalence of undiagnosed thrombosis, indicating that consideration should be given to early diagnosis and appropriate treatment to this potentially reversible cause of TAVR dysfunction. CATEGORIES STRUCTURAL: Valvular Disease: Aortic TCT-656 Prolong Blood Stasis on Transcatheter Aortic Valve Leaflets as a Possible Mechanism for Thrombogenesis Koohyar Vahidkhah, 1 Mohammad Barakat, 2 Mostafa Abbasi, 3 Shahnaz Javani, 4 Peyman Azadani, 5 Anwar Tandar, 6 Danny Dvir, 7 Ali Azadani 8 1 University of Denver, Denver, Colorado, United States; 2 University of Denver; 3 University of Denver, Denver, Colorado, United States; 4 University of Denver; 5 University of Utah School of Medicine; 6 University of Utah School of Medicine, Salt Lake City, Utah, United States; 7 St. Paul’s Hospital, Vancouver, British Columbia, Canada; 8 University of Denver, Denver, Colorado, United States BACKGROUND Formation of leaflet thrombosis following trans- catheter aortic valve replacement (TAVR) has been increasingly recognized. However, the underlying mechanisms have remained unclear. This study aimed to shed light on such mechanisms from a fluid mechanics standpoint via quantification of blood residence time (BRT) on the transcatheter aortic valve (TAV) leaflets. METHODS Unlike surgical bioprostheses, the aortic portion of the TAV frame is circumferentially surrounded by calcified leaflets in TAVR, or by degenerated bioprostheses in valve-in-valve setting (Figure 1). Two computational models representing a surgical bioprosthesis and a TAV were developed. 3D flow fields were obtained via a one-way fluid- solid interaction modeling approach validated by experimental testing. Subsequently, a particle tracking procedure was applied to calculate BRT on the valve leaflets. Finally, statistical analysis was performed to compare the BRT values in the two models. RESULTS Significantly larger values of BRT on the leaflets were ob- tained for the TAV than the surgical bioprosthesis (Figure 1). During forward flow, the mean value of BRT was 35% higher in the TAV compared to the surgical bioprosthesis (p<0.0001). During diastole, from end of closing to mid-diastole and mid-diastole to systole, BRT was longer for the TAVR model by 139% and 24%, respectively (p<0.0005). CONCLUSION TAVR, as opposed to surgical valve replacement, may alter the natural flow field around the leaflets. The geometric confinement of the TAV increases the BRT on the TAV leaflets. The increased BRT may act as a permissive factor for thrombogenesis. CATEGORIES STRUCTURAL: Valvular Disease: Aortic TCT-657 Stentless vs. Stented Aortic Valve-in-Valve Implantation: Insights from the Valve-in-Valve International Data Registry (VIVID) Alison Duncan, 1 Neil Moat, 2 Arend de Weger, 3 Joerg Kempfert, 4 Holger Eggebrecht, 5 Tony Walton, 6 Farrel Hellig, 7 Ran Kornowski, 8 Konstantinos Spargias, 9 Matheus Simonato dos Santos, 10 Oscar Mendiz, 11 Raj Makkar, 12 Mayra Guerrero, 13 Chet Rihal, 14 Isaac George, 15 Creighton Don, 16 Alessandro Iadanza, 17 Vinayak Bapat, 18 Robert Welsh, 19 Harindra Wijeysundera, 20 Rafael Wolff, 21 Sameer Gafoor, 22 Luis Nombela Franco, 23 Javier Cobiella, 24 Danny Dvir 25 1 The Royal Brompton Hospital, London, United Kingdom; 2 Royal Brompton Hospital, London, United Kingdom; 3 Leiden University Medical Center, Leiden, Netherlands; 4 Kerckhoff Clinic, Bad Nauheim, Germany; 5 Evasc Medical Systems, Jersey; 6 Epworth, Richmond, Victoria, Australia; 7 Sunninghill Hospital, Johannesburg, South Africa; 8 Rabin Medical Center, Petach Tikva, Israel; 9 Hygeia Hospital, Athens, Greece; 10 Federal University of Sao Paulo, Vancouver, Brazil; 11 Fundacion Favaloro, Buenos Aires, Argentina; 12 Cedars-Sinai Medical Center, Los Angeles, California, United States; 13 Evanston Hospital, Evanston, Illinois, United States; 14 Mayo Clinic, Rochester, Minnesota, United States; 15 Cardiothoracic Surgery; 16 University of Washington, Seattle, Washington, United States; 17 Le Scotte Hospital, Rapolano Terme, Siena, Italy; 18 Guy’s and St. Thomas’, London, United Kingdom; 19 Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada; 20 Sunnybrook Health Sciences Center/University of Toronto, Toronto, Ontario, Canada; 21 Shaare Zedek medical centre, Haifa, Israel; 22 CardioVascular Center Frankfurt, Frankfurt, Germany; 23 Hospital Clínico San Carlos, Madrid, Spain; 24 Duke University, Durham, North Carolina; 25 St. Paul’s Hospital, Vancouver, British Columbia, Canada BACKGROUND Valve-in-valve (ViV) transcatheter aortic implantation (TAVI) is an alternative to repeat open heart surgery for patients with a failing aortic bioprosthesis. Unlike degenerate stented aortic bio- prostheses, failing stentless bioprostheses lack anatomic markers which may complicate ViV-TAVI. We sought to compare clinical out- comes after ViV-TAVI in stentless versus stented bioprostheses using a large global registry. METHODS A total of 1598 aortic ViV procedures from the ViV Inter- national Data (VIVID) registry were investigated (1307 stented bio- prostheses, 291 stentless). RESULTS Stented patients were older (78.4Æ8.2 vs. 74.3Æ12.9 years, p < 0.001), but there was no difference in gender, severity of NYHA Class, diabetes, peripheral vascular disease, renal disease, previous stroke, chronic lung disease, previous stroke, or STS mortality risk scores (9.4Æ8.2 vs. 9.0Æ7.9, p ¼ 0.44) between stented and stent- less groups. Bioprosthetic failure was due to regurgitation in 57.7% of stentless bioprosthesis and 21.1% of stented valves. The effective orifice area was larger (1.31Æ0.7 vs. 0.93Æ0.63cm2, p < 0.001), and mean gradient was lower (25Æ18 vs. 38Æ17mmHg, p < 0.001) in stentless compared to stented valves Transfemoral access was similar in stentless vs. stented ViV-TAVI (71% vs. 74%), but self- expandable devices were more frequent in stentless bioprostheses (56.2% vs. 48.2%, p ¼ 0.048). Initial device malposition was more common in stentless valves (10.6% vs. 6.1%, p ¼ 0.008), as was the requirement for a second transcatheter device (7.9% vs. 3.4%, p < 0.001) and coronary obstruction (6.0% vs. 1.5%, p<0.001). However, final aortic valve area was greater (1.74Æ0.6 vs. 1.42Æ0.4cm2, p< 0.001) and post-procedure mean gradient was lower (11.7Æ6.9 vs. 17.1Æ8.9mmHg, p < 0.001) in stentless prosthe- ses. There was no difference in 30-day (6.6% stentless vs. 4.4% stented, p ¼ 0.12) and 1-year (15.8% stentless vs. 12.6% stented, p ¼ 0.15) mortality between the groups. CONCLUSION ViV TAVI for degenerate stentless bioprosthesis is challenging and associated with more device malposition and coro- nary obstruction. However, stentless ViV procedures offer improved device hemodynamics on echocardiography with similar survival rates at thirty days and one year. CATEGORIES STRUCTURAL: Valvular Disease: Aortic TCT-658 Neurologic Outcomes with Embolic Protection Devices in Patients Undergoing Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Gennaro Giustino, 1 Roxana Mehran, 2 Roland Veltkamp, 3 Michela Faggioni, 4 George Danias, 5 Usman Baber, 6 George Dangas 6 B266 JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, VOL. 68, NO. 18, SUPPL B, 2016