Six-Month Biological Response and Functionality of Balloon-Expandable Transcatheter Aortic Valve (Myval) in Aortic Banding Model

BackgroundLong-term evaluation of transcatheter heart valves (THV) in the pre-clinical setting and clinical translation of outcomes was limited.AimWe evaluate biocompatibility and durability of a balloon expandable THV system (Myval, Meril Lifesciences) at 6-month follow-up in the novel ovine aortic banding model.MethodsA surgical ascending aortic banding model was created in 11 sheep. Two weeks later, 11 Myval THV systems (20 and 23 mm) were introduced and implanted via carotid approach for a 6 month follow-up. Transthoracic echocardiography was performed at 30, 90, and 180 days. Subsequently, the animals were sacrificed and the valves with surrounding tissue harvested for pathological and radiographic evaluation.ResultsAll valves were implanted successfully. There were 2 procedure-related deaths. One sheep died prematurely on day 133 due to endocarditis and one on day 74 due to leaflet immobility caused by tight banding. Both these were not related to the device.At 6 months all valves that completed follow-up (n = 7) were functional, with no significant regurgitation, calcification, thrombi, or vegetation. At terminal follow-up mean pressure gradient was 21.9{plus minus}11 mm Hg, Vmax = 3.3{plus minus}1 m/s and ejection fraction of 53.3 {plus minus} 6%. In pathology, implant cusps were covered with endothelialized and fibrocellular neointima, whereas the conduits were fully integrated without inflammatory reaction. There were no signs of thrombus or calcifications.ConclusionsIn this novel aortic banding model, Myval THV showed optimal deployment and good hemodynamic performance at 6 months. There were no device related degenerations and healing was very advanced.