Transcatheter aortic valve replacement failure: déjà vu ou jamais vu?

T he past half decade has seen transcatheter aortic valve replacement (TAVR) emerge as the standard of care for inoperable and high-risk patients with severe aortic stenosis: randomized data have demonstrated reduced mortality with TAVR compared with medical therapy or surgery in these respective situations. Accordingly, recent research efforts have reorientated from establishing the short-term safety and efficacy of TAVR to optimizing patient outcomes and assessment of transcatheter heart valve (THV) durability. Five distinct causes of THV failure have been identified 3 : 3 are synonymous with surgical valve failure (structural valve dysfunction; prosthetic valve endocarditis [PVE]; and thrombosis) and 2 are unique to transcatheter valves (late migration ; and compression). The limited information available on the incidence of these events and resultant uncertainty of THV durability are among the most significant impediments to widespread adoption of THV technology. Anecdotal experience and, more importantly, an ever-increasing quantity of published data suggest however that acute catastrophic failures are not characteristic of THVs. History has a tendency to repeat itself, and it is notable that a similar impasse relating to the adoption of surgical bioprosthetic valves played out almost 3 decades ago. On this subject, the British surgeon Dr Donald Ross provided the following commentary in 1982: Undoubtedly valve durability emerges as the most persistent criticism of biological valves. However, we have come to recognize that failure or degeneration in a biologic valve is a slowly progressive process. This means that there is adequate warning and plenty of time for a safe, planned second operation. The message I am trying to deliver is that we should not be deflected by the mechanical valve proponents into believing that valve durability is the key factor keeping patients alive. The fact that the valve is fine and unmarked, after the patient is dead, is of little interest to anyone but the manufacturers. It is imperative that we remember that valve safety ranks more importantly than durability when related to the clinical scene. Surgical bioprosthetic heart valve thrombosis is a well-recognized , but uncommon, prosthesis failure mode. The risk of surgical bioprosthetic thrombosis is greatest in the early post-operative period, 7 and the reported incidence ranges from 0.5% to 2.3% per patient year. These rates are probably underestimated , as long-term systematic echocardiographic follow-up of surgical bioprostheses had not, somewhat surprisingly, been performed until the Placement of Aortic Transcatheter Valve Cohort 1A (PARTNER 1A) trial. 4 …