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Repair for rheumatic mitral valve disease. The controversy goes on!
  1. Manuel J Antunes
  1. Correspondence to Dr Manuel J Antunes, Center of Cardiothoracic Surgery, Faculty of Medicine, University Hospital, Coimbra, Portugal; antunes.cct.chuc{at}sapo.pt

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Valvuloplasty is now widely accepted as the best method of treatment of mitral valve regurgitation, but repair for rheumatic mitral valve disease is commonly believed to yield poorer results by comparison with other aetiologies, especially the degenerative form. This is a natural consequence of the evolutionary nature of the rheumatic inflammatory process that continues beyond surgery.

However, rheumatic valve disease assumes different formats in different populations. In the developing countries of the southern hemisphere, including South America, Sub-Saharan Africa and parts of Asia, patient populations are characterised by their low mean age (20–30 years), which renders them susceptible to repeated bouts of the disease. Hence, antibiotic prophylaxis must be continued after surgery until a much older age, and WHO now recommends lifelong prophylaxis in patients with severe valve disease or who have had valve surgery. In the vast majority of cases, mitral regurgitation is caused by elongated anterior leaflet chordae causing prolapse of the leaflet, which is usually small and retracted, as is the posterior leaflet. Dilated annulus, in most cases, and commissural fusion, relatively frequent, complete the complex set of lesions that makes repair technically so much more difficult.

However, the major problem here is the increased need for reoperation for progressive fibrosis and distortion of the valve caused by the progression or recurrence of the rheumatic process (figure 1). But it is essential to emphasise that valve replacement in these populations also has poorer outcomes, in some reports clearly worse than those of repair, mainly due to deficient socioeconomic conditions leading to non-compliance to therapy. In this set-up, prosthetic valve replacement is plagued by several types of complications that carry high mortality and morbidity. Thrombosis and thromboembolism are the most feared; thrombosis of mechanical prosthesis is a very lethal complication with a mortality of up to 60% and is more frequent in the mitral valve position. On the other hand, degeneration of bioprostheses evolves much faster in younger patients, thus requiring multiple reoperations, each one with added mortality (and morbidity), varying with the condition of the patient and the experience of the surgical team, but ranging from 3% to 10%.1

Figure 1

Repaired mitral valve showing fibrosis and distortion of the tissues caused by progression/recurrence of the inflammatory rheumatic process.

Yet, my own experience with such a population in Johannesburg, South Africa, attests to the superiority of repair in this situation.2 In a group of 241 patients with a mean age of 21.5 years, the overall survival was 89% and freedom from reoperation was 84% at the 6-year follow-up. Similar experiences have been reported by others.3

By contrast, in developed countries, rheumatic valve disease represents only a reminiscence of the subdevelopment of earlier decades and is seen in the operating rooms at a much later age (mean 50–55 years).4 The disease is in a completely different phase, with a mostly burnt-out histological process, unlikely to progress except for the deposition of calcium. Isolated annular dilatation is the cause for regurgitation in approximately half of the cases. Mitral valve repair in these situations tends to be technically easier. On the other hand, valve replacement in these generally better socioeconomic and educated patients yields better results because of a far better compliance to therapy.5

Hence, when evaluating and comparing surgical results of rheumatic valve disease, it is of utmost importance to characterise well the respective populations as these two are not at all comparable. It is in this context that we must view the paper published in Heart by Kim et al,6 from Seoul, South Korea. The authors analyse the long-term survival and valve-related outcomes in 1731 consecutive adult (>17 years) patients with a mean age of 52.3±12.5 years who had mitral valve surgery for rheumatic mitral disease during a 19-year period ending in 2015, comparing repair (n=294; 17%) and replacement with either mechanical valves or bioprostheses. The two groups were significantly different inasmuch as patients undergoing repair were younger (mean age, 43.9±13.9 years) and had more predominant mitral regurgitation than those in the mechanical and bioprosthetic replacement groups.

After a maximum follow-up of 20 years, the authors found that there was no significant difference in the late mortality between repair and replacement, but the risk of valve-related complications was significantly lower in the repair group. Furthermore, the incidence of reoperation was not significantly different between groups. Hence, their conclusion that “valve repair in well selected patients with severe rheumatic mitral disease led to comparable survival, but superior valve-related outcomes compared with valve replacement surgery”.

The conclusions derived from this study in a very large patient cohort of patients are not really new and, in my view, the statement that ‘there is a general agreement that the majority of patients with severe rheumatic mitral valve disease who require surgery are best treated with valve replacement surgery…’ is not correct. On the contrary, as discussed above, there is now a growing consensus favouring valve repair in this pathology because of the excellent short, mid-term and long-term outcomes in experienced centres. Indeed, this paper from our Korean colleagues adds to that evidence.

But I was unpleasantly surprised to see that only 17% of their patients had repair, which must mean that there was an important selection. It is also important to note that this 19-year-long series of mitral valve repair was distributed by seven surgeons, that is an average of 42 cases per surgeon (just over two per year, per surgeon!), which, evidently, does not make for a significant individual experience.

The spectrum of pathology in the study population was quite wide, with a predominance of stenotic lesions, having in mind that two-thirds (67%) of the repair patients required commissurotomy. Naturally, this spectrum influenced the type of procedure performed, repair versus replacement, and the perioperative mortality was much higher in the latter (mechanical valve, 4.3% and bioprostheses, 6.6% vs repair, 1.7%), which would otherwise be difficult to understand since isolated mitral valve replacement is usually technically simple and takes less time to perform than a repair in this pathology.

On the other hand, the authors opted to leave children and adolescents out of the analysis, and we do not know how many were there during the study period. In fact, this series cannot be compared with others originating from other parts of Asia, including young patients or exclusively formed of children.2 As written above, it is well known that repair for rheumatic mitral valve disease in the adult patients has better results than in the very young patients characteristic of the endemic regions of developing countries. This is not sufficiently discussed by Kim et al. Again, the rheumatic process in the adult population in the fifth to seven decades of life is quiescent, while in younger patients it is still active, which has a significant impact in the medium-term and long-term results. This could also have been the cause for the similarity in the incidence of reoperation in this paper.

Finally, the authors recognise that “extensive rheumatic MV repair procedures such as pericardial leaflet extension or calcified MV peelings were limitedly performed in their institution because of the prevailing assumption that far advanced rheumatic pathologies requiring more complex repair procedures are better treated by prosthetic valve replacement”.

Leaflet extension is not new. It was used extensively in the late 1970s and early 1980s, then with mixed outcomes, but the results reported recently have been very encouraging. Leaflet extension adds the benefit of increasing leaflet mobility and allowing the use of a larger ring for annuloplasty, which must always be part of the procedure, although this enlargement is somewhat limited by the intertrigonal distance. Nonetheless, this technique is very operator dependent and must be meticulously performed,7 which requires experience.

It is my opinion that the authors appear to have exactly the type of population where such ‘extensive’ procedures are indicated. Evidently, however, their population is culturally more advanced, thus more adequate for prosthetic valve replacement, because of better compliance to anticoagulation therapy.

In conclusion, not all rheumatic populations are equal. A better knowledge of the rheumatic valve pathology and the evolution of repair techniques have contributed to improved results. Hence, valve repair, however challenging,3 is still worthwhile and the percentage of valves repaired increases with the experience of the surgeon and the will to preserve the valve. It is vital that all surgeons dealing with this type of pathology gain adequate experience and overcome the unavoidable learning curve, which can only be obtained by exposure to enough patients with this condition.8

In my recent experience with young patients originating from several Portuguese-speaking African countries operated on in Coimbra and with those operated on in Mozambique during regular surgical missions there conducted by my surgical team, it has been possible to successfully repair the mitral valve in more than 90% of the patients under 20 years of age with durable results and a low incidence of reoperation up to 15 years of follow-up.

In these conditions, mitral valve replacement can only be justified when good repair is not feasible.

References

Footnotes

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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