Aortic valve fenestrations: supporting character also deserves spotlight!

Aortic valve fenestrations (AVF) are a common finding in patients being considered for aortic valve (AV) repair for aortic insufficiency (AI); yet, little is known about the pathogenesis of AVFs and the manner in which they contribute to valve dysfunction. In this study by Shraer et al. [1], the authors undertake a detailed examination of AVFs in the context of AV repair and offer some important new insights. This topic is an important one for all AV repair surgeons for a number of reasons. Firstly, AVFs are common. From a review of 919 examined hearts from 4 autopsy studies, Zhu et al. [2] found that 55.9% of individuals presented with AVFs in their AV leaflets. The authors also found that fenestrations rarely manifested clinically or affected AV competence, through a review of 39 case reports and 3 case series with 63 patients. When involved in the mechanism of AI, AVFs tended to be larger, more central, and spontaneously ruptured. It is likely that AVFs are underreported due to limitations in identification methods, as they are not well seen on echocardiography [3, 4]. Despite being common, AVFs are infrequent contributors to AI. In a retrospective cohort study of 382 patients, Yang et al. [3] reported that 12 patients (3.1%) had fenestration-related AI. Furthermore, in a case series report of 1133 AV surgery patients, Cheruvu et al. [4] reported that 42 had AVFs and 26 had surgery for AI primarily. The frequent presence of AVFs in normal and regurgitant AVs, and their uncommon involvement in AI invokes a fundamental question: What is the role of AVFs in normal valve function and what is their contribution to the natural history of AI? It also creates an important conundrum for surgeons: Does the presence of AVFs signal a weakness in cusp tissue and thus represent a risk factor for late failure? Should AVFs be repaired even though they are not contributory to valvular insufficiency? In this issue of EJCTS, Shraer et al. [1] published a large, single-centre, cohort study that examines the impact of AVFs, respected or fixed, on AV repair surgery outcomes. From 2003 to 2019, 618 patients underwent AV repair and after propensity score matching, 167 pairs of patients in the non-AVF group and AVF group displayed similar survival (90.3% vs 95.8%), reoperation (6.7% vs 5.2%), grade ≥3 AI (6.4% vs 4.4%) and grade ≥2 AI (28.9% vs 37.1%) over the follow-up period. The authors concluded that the presence of AVFs did not impact survival, reoperation or significant AI. The authors used their clinical judgement and some guiding principles in deciding which AVFs to repair, which to leave alone and which AVFs warranted valve replacement. The guidelines that they followed were: fenestrations were respected if they (i) involved <1/2 of the free margin length and (ii) were thick (>1 mm) and has a solid free margin (large base of implantation). If larger, elongated or thin, the fenestrations were repaired using a running suture or decellularized bovine pericardial patch. Despite some of the limitations of this study including its single-centre design, incompleteness of follow-up, small numbers of repaired fenestrations, the conclusion of the study are important and support the notion that AVFs should generally not be a contraindication for AV repair, if other characteristics for potential successful repair is favourable. Our experiences and those from other groups also corroborate the principles articulated by the authors. In the majority of cases, AVFs are ‘innocent bystanders’ to the pathophysiology of AI and therefore, need not be repaired. However, what is yet unclear is whether certain characteristics of AVFs may be related to late failure. Future studies of AVFs should therefore, go beyond their mere presence or absence, but perhaps characterize in more detail the number of fenestrations, number of cusps involved, the cusp quality, their location, size and involvement within the coapting surface of the leaflets. With video capabilities being more readily available in operating rooms, there is a greater opportunity to visually capture many of these elements in a systematic manner and evaluate their impact on outcomes. These additional parameters would then need to be combined with other known predictors of recurrent AI (e.g. coaption length, effective height, preoperative left ventricular end-systolic diameter, post-repair annular diameters) to fully appreciate their impact [5]. As the field of AV repair matures, clinicians will need to focus their efforts further on these issues in order to further understand pathophysiology, standardize technical approaches and improve outcomes. Shraer et al. take an important step towards this process. It’s time to place AVFs in the spotlight!

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