Taking tricuspid valve surgery to the next level: repair techniques below the annulus

With growing recognition that the severity of tricuspid valve regurgitation (TR) is associated with increased morbidity and mortality [1], the tricuspid valve has evolved from ‘forgotten’ to ‘center stage’. It currently seems to be accepted that tricuspid valve surgery is high risk per se [2] and its prognostic impact is questionable [3]. As a consequence, physicians and patients are reluctant to undergo high-risk procedures for possibly only moderate symptomatic improvements. Thus, less-risky interventional treatment alternatives are on the rise at the moment. Assessing this development from a different perspective reveals several similarities to mitral valve treatment. As for the tricuspid valve, many patients with mitral regurgitation also have a functional pathomechanism as the underlying cause [4, 5]. Surgery is also considered a higher risk in this subpopulation (due to poor ejection fraction and patient comorbidities mostly present), the prognostic impact is uncertain [6] and the durability of an annuloplasty procedure alone is poor [7]. It is therefore no surprise that interventional clipping procedures currently outnumber surgical procedures [8]. This analogy of TR with functional mitral regurgitation may also suggest the same pattern for the tricuspid valve in the near future. However, with the exception of valve replacements (which are generally perceived inferior to a durable repair), all repair strategies for both functional mitral and tricuspid regurgitation are challenged by questionable long-term durability. Reviewing the literature on tricuspid valve annuloplasty focusses on the comparison of ring, band and suture annuloplasty techniques, suggesting that ring or band may be superior to De Vega type suture annuloplasty [9]. However, if one looks at the available data on long-term outcomes after tricuspid valve repair, return of severe TR is actually similar to the high rates of up to 30% at 1 year and even 60% at 2 years with the mitral valve [7]. The surgical response to recognizing poor durability for functional mitral regurgitation has been the development of subvalvular techniques that anchor the papillary muscle in different ways to the annuloplasty repair generating greater durability [10–13]. Whether these technical improvements generate the expected clinical improvement is currently being tested in a randomized trial (NCT03470155), but individual reports and non-randomized data already suggest a significantly better treatment effect [14]. Takeshita et al. [15] present such subvalvular techniques in this issue of the EJCTS also for the tricuspid valve. In addition, they clearly illustrate the complex interplay of the different patho-mechanisms in functional TR with severe leaflet tethering. The authors could show that patients treated with annuloplasty and only 1 subvalvular procedure (annular repositioning to reduce septal leaflet tethering or papillary muscle bundling) presented with higher TR rates at 2-year follow-up than those with combined subvalvular procedures. In those treated with a combination of 2 subvalvular procedures, such as annular repositioning and papillary muscle relocation or bundling in addition to annuloplasty, no recurrence of TR was observed at 2-year follow-up. The authors imply that the anterior portion of the TV apparatus may require isolated, additional treatment as relevant RV dilatation occurs. However, the septal leaflet with the shortest height and often low mobility due to special subvalvular anatomy also frequently presents with severe tethering. Thus, the anterior and septal papillary muscles probably reflect the main therapeutic target for subvalvular techniques providing a reliable long-lasting repair. This surgical finding is further supported by us [16] and others [17–19] describing different surgical techniques (papillary muscle sling, approximation, bundling or relocation) addressing the subvalvular apparatus to reduce leaflet tethering with promising results. We proposed a subvalvular triangle with a Goretex suture that anchors the subvalvular apparatus to the annuloplasty band or ring to secure the valve’s closing geometry and therefore improve durability. We know it works for the first year (longer follow-up is ongoing). Based on these findings and the current recognition that isolated tricuspid surgery can be performed at low risk [20], the perspective of a durable tricuspid valve repair may substantially improve the attractiveness of an isolated surgical approach for a leaky tricuspid valve. The current interventional repair strategies are much less successful in terms of eliminating TR and long-term data are still missing. The number of patients suffering from severe TR is immense [4]. It is therefore important for surgeons and cardiologists to combine their forces, compare their techniques with randomized trials and thereby take the treatment of tricuspid regurgitation to another level. For the surgeon in the operating room, this means to a subvalvular one.