A new age of aortic valve repair

We are in an era of development in aortic valve intervention. Industry-funded advances in transcatheter valves and new-age bioprosthetic valves all promise long-term results, but so far only provide short-term data to evaluate. In the meantime, aortic valve repair techniques have progressed considerably in the past 10 years. We can now benefit from mid- to long-term data, which shows the strength of aortic valve repair in terms of survival, freedom from major adverse valve events and now freedom from reoperation. This excellent study by Jasinski et al. [1] is a fine example of how durable aortic valve repair can be in aortic insufficiency (AI), specifically in the bicuspid population, which was once the focus of valve repair sceptics. Jasinski et al. should be congratulated for an in-depth analysis of different repair techniques, which throws further light on already established evidence for dealing with different components of the aortic root. This study shows a survival of 99.5% during a follow-up period of 17 years (mean of 5 ± 3.5 years). Freedom from severe AI was 95%, and freedom from reoperation was 91.8% at 7 years. Identified risk factors for reoperation included no circumferential subvalvular annuloplasty, not addressing the STJ, leaflet resection, and type 2 BAV (minor and true forms of unicuspid valve). Jasinski et al. add further support to the need of addressing every component of the aortic root when undertaking aortic valve repair, particularly the annulus and the sinotubular junction (STJ). The root comprises the annulus, valve cusps, sinuses and STJ. It can be thought of as having 2 annuli, the subvalvular annulus (basal ring) and the STJ. Managing the subvalvular annulus and the STJ is paramount in achieving good leaflet coaptation, and critically, the STJ must not be forgotten about in this undertaking. Large pooled echocardiographic studies show that the mean STJ diameter is larger than the aortic annulus by a ratio of 1.2 [2]. AI in the western world primarily involves some dilatation of the aortic annulus and/or STJ, even when the aorta is not dilated. Restoring the STJ/annulus ratio back to its physiological value of 1.2 will improve long-term durability and freedom from reoperation. In the case of valve-sparing root replacement, STJ annuloplasty is carried out by the synthetic graft. When performing the remodelling technique with subvalvular external ring annuloplasty, a downsizing algorithm according to the native aortic annulus diameter is used to achieve the STJ/annulus ratio of 1.2 [3]. The synthetic graft will produce a neo-STJ equal to the size of the graft, and a neo-annulus will be internally 5 mm smaller than the ring (as the thickness of the annulus is 2.5 mm on either side). In the reimplantation technique, depending on the sizing algorithm, the ratio of 1.2 is similarly restored unless the graft is oversized compared to the diameter of the native annulus. The importance of addressing both the annulus and the STJ can be seen nowhere more clearly than in cases of aortic valve repair for the treatment of isolated AI, where the aortic sinuses and ascending aorta are <40–45 mm. A comparison between single (subvalvular) annuloplasty and double (subvalvular and STJ) annuloplasty using external rings shows an improvement in recurrent AI grade >2 from 30% in the single annuloplasty group to 0% in the double annuloplasty group and an improvement in valve-related reintervention from 26% in the single annuloplasty group to 3% in the double annuloplasty group at 6 years [4]. Commissural orientation has emerged to be a key component of bicuspid repair techniques. The present study confirms the findings by Schneider et al. [5] that an asymmetrical BAV is a risk factor for recurrent AI. This has led to a shift in recent years towards changing the commissural orientation towards a more symmetrical 180° configuration to improve long-term durability. The vast majority of BAVs with AI have prolapse of the fused cusp, requiring central plication sutures to be placed. This makes the non-fused cusp take over the opening dynamics of the valve. By changing the orientation to 180°, the non-fused cusp is lifted up and its effective height increased. This helps avoid plication of the non-fused cusp, an important factor in preventing increased post-operative valve gradients. To change a BAV to a symmetrical configuration requires placement of the commissures at 180°. This is done at the STJ level, either using the tube graft in the case of valve-sparing root replacement or ascending aorta replacement or using the external ring in the case of isolated aortic valve repair with double sub- and supra-valvular annuloplasty. Furthermore, sinus plication of the larger fused sinus can help orientate the root to a more symmetrical configuration [6]. Historically, the ‘gold standard’ for non-elderly patients with aortic valve disease has been mechanical aortic valve replacement (AVR) or root replacement (mechanical Bentall). Large meta-analyses have now shown us that long-term outcomes from these procedures carry a significant risk of late mortality, loss of life expectancy, and major morbidity. Korteland NM et al. have shown that mechanical AVR carries a linearised mortality rate of 1.6% per year, equating to 84% survival at 10 years [7]. A 45-year old undergoing a mechanical AVR would have 20 years event-free loss of life expectancy, with an incremental bleeding risk of 0.9% per year. A mechanical Bentall would incur a 2.0% risk of mortality per year, meaning an 80% survival at 10 years [8]. The outcomes from this study and other centres of aortic valve repair supersede those of prosthetic valve and root replacements. The paradigm of treatment for AI in both tricuspid and bicuspid aortic valves has now shifted to repair. The next step is large-scale multi-centric analysis of aortic valve and root repair outcomes from different centres. The AVIATOR Registry is an open-access database for aortic valve and root repair procedures from the Heart Valve Society [9]. With current data accumulated from around 60 centres from 4 continents, and over 7000 patients, we eagerly await the imminent evaluation of long-term patient outcomes in all aortic valve repair techniques.