LAUSR

Recently, industrial technology and approaches in aortic valve replacement (AVR) have evolved in ways cardiac surgeons and cardiologists would have never imagined. In particular, transcatheter aortic valve implantation (TAVR/TAVI) has had promising results in comparison to traditional surgical AVR (SAVR). As a result, previously high‐risk and inoperable patients now have a life‐ prolonging, low‐risk intervention. In addition, TAVR's efficacy and safety extend to patients with failed bioprosthetic heart valves (BPV). As first reported in 2007 by Wenaweser et al., valve‐in‐ valve (ViV) TAVR is safe and possible. However, concerns arose regarding patient‐prosthesis mismatch (PPM), especially in patients with small BPVs. Severe PPM (i.e., indexed effective orifice area [EOA] <0.65 cm/m), in particular, has a significant impact on survival after both SAVR and TAVR. Fortunately, the rapidly evolving bioprosthetic valve fracture (BVF) technique can prevent PPM. Thus, BVF has emerged as a feasible option for selected patients undergoing ViV TAVR, especially in undersized prostheses, with remarkable improvement in hemodynamic results. In this issue of the Journal of Cardiac Surgery, Sá et al. performed a meta‐analysis and systemic review. Despite the sparse data, they provided insight into the short‐term outcomes of this approach. They pooled the results from 242 patients after reviewing four observational studies analyzing early outcomes of BVF and ViV TAVR for structural BPV degeneration. They found that periprocedural mortality was 2.1%, which echoed the reported rate from various registries of 1.1%–4.2%. With the exception of the lower rate of coronary obstruction of 1.5% in comparison to 3.5% for ViV TAVR, the rates of annular rupture, stroke, paravalvular leak, and pacemaker implantation were comparable to conventional TAVR, accounting for <1.0%, <1.5%, <1.0%, and <1.0%, respectively. Given the anatomical complexity and challenge of ViV implantation, BVF would be expected to carry more risk; however, perhaps the careful selection of patients for such novel intervention played a major role in the low morbidity and mortality rates. Remarkably, aortic valve means gradients improved significantly, as well as aortic valve area following ViV BVF. However, the improvement trend remained too low, resulting in severe PPM in a considerable number of patients. The authors attributed this to the fact that those patients received a small‐sized bioprosthetic valve implanted during the index SAVR. Theoretically, BVF can optimize the expansion of the BPVs and improve the prosthetic EOA, thereby avoiding PPM or perhaps reducing its impact on morbidity and mortality. However, this study did not observe the achievement of the above‐mentioned purpose. As the authors acknowledged, this study was limited by many factors: the limited data were obtained from observational studies that are moderately confounded (based on ROBINS‐I criteria) and that produced a biased estimate from only two highly weighted studies accounted for the majority of the sample size. In addition, the authors used unadjusted estimates from the studies included in their meta‐analysis. These estimates are subject to confounding, which are not recommended to be used. Nevertheless, there was no evidence of significant impact on short‐term mortality, which was, in turn, limited to 30 days. Considering that related mortality reported with PPM after TAVR were from a cohort of patients followed for 354 days, this leaves the question of the value of this intervention compared to ViV TAVR without fracture on long‐term mortality. Furthermore, these promising outcomes—from low PPM to improved aortic valve hemodynamics by reducing the mean aortic gradients— were likely obtained from carefully selected patients. There is current debate about whether fracturing the degenerated BPV before TAVR deployment “Fracture & TAVR” has any significant benefit over BPV fracture after TAVR deployment “TAVR & fracture.” TAVR & fracture may harm, at least theoretically,