Transcatheter aortic valve-in-mechanical valve replacement: a first-in-human study

Surgical aortic valve replacement has progressed considerably since the 1950s.1,2 Although mechanical valves offer superior durability, the preference for bioprostheses has increased due to their anticoagulation-free profile.3 Transcatheter aortic valve implantation (TAVI) is an established therapy for failing bioprostheses,4,5 but its use in mechanical valve failure remains largely unexplored.6 This translational investigation evaluates a strategy to intentionally disrupt bileaflet mechanical aortic valves, retrieve embolized disc fragments, and implant a transcatheter valve without open-heart surgery. The central hypothesis was that mechanical valve dysfunction in inoperable patients can be treated percutaneously via controlled disc dislodgement followed by TAVI. The secondary hypothesis is that anticoagulation may be replaced by single antiplatelet therapy when no alternative indication exists. The primary endpoint was VARC-3 procedural success; secondary endpoints were mortality, device thrombosis, heart failure readmissions, and bleeding or ischaemic events. Bench testing demonstrated that snaring the discs failed to dislodge them and blocked their function longer time. On the contrary, disc dislodgement was rapid and feasible with balloon inflation at 2–4 atm. Both large balloons (18 mm) and peripheral balloons (10–14 mm) successfully dislodged the discs without balloon rupture; specifically, peripheral balloons allowed single disc detachment and second disc trapping in position with the implanted balloon-expandable TAVI, suggesting that it might be a better alternative. An animal study was then performed at CNIC (PROEX041.4/24). Large white pigs (60–80 kg) underwent heterotopic mechanical valve implantation (to avoid extracorporeal circulation) or orthotopic implantation (for anatomical fidelity), using commercially available bileaflet valves (Open Pivot™, Regent™, Overline™). After ≈1 month, surviving animals underwent valve-in-mechanical prosthesis (ViMech). Bilateral femoral access was used: one for the Ono Filter™ in the ascending aorta with a balloon positioned inside to fracture the discs and the other for the TAVI device (Myval™ or Evolut™). Once discs dislodgement was confirmed fluoroscopically, the balloon/filter system was withdrawn and TAVI deployed immediately using the mechanical sewing ring as a landmark. Aspirin (100 mg/day) was initiated; vitamin K antagonists were not resumed. Computed tomography (CT) and echocardiography were performed at baseline, pre-TAVI, post-TAVI, and at follow-up; necropsy followed final imaging.