Quo Vadis Mitral Valve Repair? From a Definite French Correction (1983) to a Possible Australian Disconnection (2023)
2024; Elsevier BV; Volume: 33; Issue: 1 Linguagem: Inglês
10.1016/j.hlc.2024.01.007
ISSN1444-2892
Autores Tópico(s)Cardiac and Coronary Surgery Techniques
ResumoThose who cannot remember the past are condemned to repeat it (George Santayana [Jorge Agustin Nicolás Ruiz de Santayana y Borrás], Spanish–American philosopher, in The Life of Reason, 1905.) In the last half-century, there have been few presentations that have exerted a powerful influence on clinical practice in adult cardiac surgery. In 1983, Dr Alain Frédéric Carpentier’s Cardiac valve surgery—The French Correction was one such presentation [[1]Carpentier A. Cardiac valve surgery - the “French correction”.J Thorac Cardiovasc Surg. 1983; 86: 323-337Abstract Full Text PDF PubMed Google Scholar], delivered as the Honoured Guest Lecturer at the 63rd Annual Meeting of The American Association for Thoracic Surgery in Atlanta, Georgia, USA, and outlining a mitral valve repair method that restored normal valvular anatomy. Now, 40 years later, and in this issue of Heart, Lung and Circulation, Cheng et al. present their findings of the state of play in New South Wales (NSW), the most populous state in Australia, with regards to mitral valve surgery [[2]Cheng Y.-Y. Shu M.W.S. Rubenis I. Vijayarajan V. Hsu A.C. Hyun K. et al.Trends in isolated mitral valve repair or replacement surgery in Australia: a statewide cohort linkage study.Heart Lung Circ. 2024; 33: 120-129Google Scholar]. Their focus was on how many mitral valves are repaired as opposed to replaced. From 2001–2018, Cheng et al. identified 5,693 patients who had open-heart mitral valve surgery. They included patients who had undergone concomitant coronary bypass grafting (CABG) and excluded patients who had undergone other valve surgery. In brief, the salient findings are that mitral valve repair was performed in 2,020 (35%) patients, 2,017 (35%) patients received a bioprosthetic replacement, and 1,656 (29%) had a mechanical replacement. Over the course of the 17 years, the incidence of mitral valve repair was essentially unchanged from 34%–38%, the incidence of bioprosthetic replacement increased from 22% to 50%, and the incidence of mechanical replacement decreased from 45% to 13%. Overall, the annual volume of mitral valve surgery increased from 430 to 571 patients. Cheng et al. used an administrative database, the Admission Patient Data Collection (APDC) database, to access the requisite data. This database does not record echocardiographic information nor the aetiology of the mitral valve pathology, and the authors acknowledge these limitations. The patient demographics revealed a relatively very high documentation of a “history of rheumatic fever” in 1,046/5,693 (about 18%)—this seems odd in the first world, but Cheng et al. do not comment on this, beyond how repair rates may be affected. However, I would hazard a guess that this history would not translate automatically to rheumatic mitral valve pathology. In 30 years of active practice, from my first entry into a cardiac theatre (1984) to my clinical retirement (2013), and across three Australian states and England, I doubt if I have seen more than two dozen rheumatic mitral valves. Despite the pot pourri of mitral valve aetiologies and the inability to numerically distinguish between ischaemic, degenerative, congenital, and rheumatic causes, in my view, the authors are correct in their conclusions— that mitral valve repair is potentially underutilised despite having superior outcomes to mitral valve replacement. And this is why this paper is important. Making no apology for modifying a well-known idiom, it is the canary chirping in the coalmine. Frankly, it is screeching like an eagle. The overwhelming majority of these patients had degenerative mitral valve disease, as would be expected for this population. This is the focus of whether a repair was performed, and these authors demonstrated the superior benefits of mitral valve repair over replacement in their cohort of patients. Patients who had a repaired mitral valve had a significantly lower hospital, 1-year, 10-year and beyond mortality; there was also a shorter hospital stay with repaired valves. The authors question why there was such a low incidence of repair in NSW, and why some surgeons repaired a high percentage of valves and others did not [[3]Anyanwu A.C. Bridgewater B. Adams D.H. The lottery of mitral valve repair surgery.Heart. 2010; 96: 1964-1967Crossref PubMed Scopus (57) Google Scholar]. Cheng et al. were unable to provide outcomes of post discharge rates of endocarditis, anticoagulant related problems, or thromboembolic events. However, it is known that these important events are significantly reduced with a repaired mitral valve. The findings by Cheng et al. of the superior benefits of repairing a degenerative mitral valve as opposed to replacement are wholly unsurprising, at least to me. In 1964, C. Walton Lillehei and colleagues, in Minneapolis, MN, USA, observed that the left ventricle assumed a spheroidal shape after a mitral valve replacement as opposed to its normal ellipsoidal shape [[4]Lillehei C.W. Levy M.J. Bonnabeau R.C. Mitral valve replacement with preservation of papillary muscles and chordae tendineae.J Thorac Cardiovasc Surg. 1964; 47: 532-543Abstract Full Text PDF PubMed Google Scholar]. Lillehei et al. reasoned that this was due to the excision of the mitral valve. By preserving the entire mitral valve apparatus, the mortality of mitral valve replacement was reduced from 37% to 14%. Two decades later, Sarris et al., led by D. Craig Miller, in Stanford, CA, USA, measured load independent indices of ventricular contractility in sheep, and found that chordal integrity was essential in optimising left ventricular systolic performance; that is, a loss in contractility after chordal detachment could be reversed with chordal reattachment [[5]Sarris G.E. Cahill P.D. Hansen D.E. Derby G.C. Miller D.C. Restoration of left ventricular systolic performance after reattachment of the mitral chordae tendineae. The importance of valvular-ventricular interaction.J Thorac Cardiovasc Surg. 1998; 95: 969-979Abstract Full Text PDF Google Scholar]. We do not have to manage this issue at all, if the mitral valve is repaired rather than replaced. By the late 1960s, others, including Frank Gerbode in San Francisco, CA, USA and Charles Dubost in Paris, France, to name a few, had made significant progress in achieving reproducible durable repairs. In 1992, at the Australian and New Zealand Society of Cardiothoracic Surgeons Annual Scientific Meeting, I presented the results of degenerative mitral valve repair from Dr Cedric Deal (Sydney). This was a large series with the longest follow up outside Europe at that time [[6]Alvarez J.M. Deal C. Loveridge K. Brennan P. Eisenberg R. Ward M. et al.Repairing the degenerative mitral valve: ten- to fifteen-year follow up.J Thorac Cardiovasc Surg. 1996; 112: 238-247Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar]. From 1969–1992, 155 patients, mean age 61 years, underwent mitral valve repair. All patients were in New York Heart Association (NYHA) functional classes III and IV before operation. The operative mortality was 3.9%, the incidence of a failed repair was 4.5% at 6 months, and the freedom from reoperation or from greater than mild regurgitation was 85% at 15 years. Freedom from thromboembolic events or endocarditis were 90% and 96%, respectively, and survival was 45% at 15 years, with 90% of patients in NYHA I–II. Over the last 10 years of the series, the operative mortality was 1%, and failure rate at 1-year was 3%. Cedric Deal had spent time with Frank Gerbode in the USA. The technique of repair involved resection of 60%–70% of the affected posterior mitral leaflet (PML) and a three to four basal suture annuloplasty, instead of using an annuloplasty ring. Generally, anterior mitral leaflet (AML) pathology was present in some 15% of patients, and was also repairable [[7]Alvarez J.M. Teoh N. Deal C.W. Repairing the degenerative anterior mitral valve leaflet.Ann Thorac Surg. 1992; 54: 1229-1230Abstract Full Text PDF PubMed Scopus (5) Google Scholar, [8]Alvarez J.M. Gray D. Choong C. Deal C.W. Repair of the anterior mitral leaflet.Aust N Z J Med. 1993; 23: 279-284Crossref PubMed Scopus (5) Google Scholar]. In 1992, from memory, there were about 50 cardiac surgeons in Australia and apart from Dr Deal, Peter Brady and Alan Farnsworth (Sydney), Serge Lubicz and George Stirling (Melbourne), and Michael Gardner (Brisbane) had also expressed significant interest in repairing the mitral valve. This presentation was not as well received as Carpentier’s, as I vividly recall the chief examiner at the time suggesting that these results suggested the surgeon might sell brushes rather than repair mitral valves! However, the encyclopaedic volume of literature that exists confirming the superior benefits of valve repair compared with valve replacement, not only of reduced operative mortality, improved long term survival, freedom from thromboembolism, and from endocarditis, as well as from the need for anticoagulation (or at least allowing for a reduced level of anticoagulation) is overwhelming, and unquestionable. The crux of the matter is what percentage of degenerative mitral valves should be effectively repaired by a trained cardiac surgeon? This is not a difficult question to answer, as the majority of degenerative mitral valves have essentially P2 prolapse—that is, prolapse of the central component of the posterior mitral leaflet—as the main issue. This is a technically undemanding repair operation and the vast majority of these degenerative mitral valves, barring significant calcification and/or significant fragile tissues, should be repaired. Cheng et al. reported a repair rate of 34%–38% across eight centres and about 50 surgeons in 2019; data on individual surgeons and centres was unavailable. Of the minority (15%–30%) of mitral valves that have added significant pathology (i.e., AML pathology) other than P2 prolapse, there are many ways to achieve a successful repair which do not require the genius of a Carpentier. Simple plication of 10%–15% of the AML is all that may be required, or the Alfieri technique for a central anterior leaflet (A2) prolapse is a durable option, and double breasting the A3 component of the AML for prolapse of this segment have been well described for decades, and are technically undemanding in my experience [[7]Alvarez J.M. Teoh N. Deal C.W. Repairing the degenerative anterior mitral valve leaflet.Ann Thorac Surg. 1992; 54: 1229-1230Abstract Full Text PDF PubMed Scopus (5) Google Scholar,[8]Alvarez J.M. Gray D. Choong C. Deal C.W. Repair of the anterior mitral leaflet.Aust N Z J Med. 1993; 23: 279-284Crossref PubMed Scopus (5) Google Scholar]. Carpentier was able, with great élan, to restore a totally floppy valve with all six segments prolapsing: he was the Bradman or Pelé of his time. His techniques of chordal shortening are, in my view, difficult to achieve. The margin for error is narrow; I have witnessed papillary muscle tip necrosis on several occasions at the hands of experienced surgeons. So too, the concept of shortening elongated chordae tendineae seems incongruous. I am unaware of a significant manuscript expressing the durability of Gore-Tex sutures at 10 years, though many surgeons use them successfully. Where I disagree, in part, with Cheng et al. is regarding the percentage of degenerative mitral valves that should be able to be repaired by a competent cardiac surgeon. I do agree that 34%–38% is sub-par and unacceptable. For isolated P2 prolapse, I think it should be near 100%; with associated AML pathology (i.e., A2 and A3 prolapse) I would suggest 80%–90%. Whether a degenerative mitral valve is repaired or replaced, should not be the lottery to which Cheng et al. alluded [[3]Anyanwu A.C. Bridgewater B. Adams D.H. The lottery of mitral valve repair surgery.Heart. 2010; 96: 1964-1967Crossref PubMed Scopus (57) Google Scholar]. Indeed, Cheng et al.’s findings, have demonstrated that action is required. What to do first is to assess the magnitude of the problem by verifying Cheng’s data by accurate assessment of what percentage of degenerative mitral valves are repaired by surgeon, by centre, in NSW. Wayne et al. has reported from, the Australian and New Zealand Society of Cardiothoracic Surgeons (ANZSCTS) database on 4,420 patients with degenerative mitral valve disease, finding wide variability in repair rates of 63%–80% per surgeon, and 55%–78% by hospital during 2008–2017 [[9]Wayne S.L. Martin C. Smith J.A. Almeida A.A. Mitral valve repair rates in degenerative mitral valve disease correlate with surgeon and hospital procedural volume.J Card Surg. 2021; 36: 1419—26Crossref Scopus (2) Google Scholar]. Cheng et al. is aware of this Australian data; it behoves the Cardiac Society of Australia and New Zealand and ANZSCTS to provide this information promptly to these researchers. If there is an incidence of rheumatic mitral valve pathology of 30%–40% in NSW, then ostensibly there may not be a problem with degenerative mitral valve repair. If so, I will happily stand corrected. What to do next is obvious. By way of example, in 1991, Dr Doug Baird, as head of the Board of Cardiothoracic Surgery mandated that all trainees in Sydney rotate through Royal Prince Alfred hospital for a semester of thoracic surgery under the aegis of Dr Brian McCaughan. Dr McCaughan had spent considerable time at Memorial Sloan Kettering in New York, USA. In my own experience and witnessing that of others, like Cedric Deal with Frank Gerbode, the beneficial and profound impact of working alongside master surgeons cannot be overemphasised. There are excellent surgeons in Australia currently, with proven track records in mitral valve repair; far exceeding the numbers I presented in 1992 [[10]Gardner M.A. Hossack K.F. Smith I.R. Long-term results following repair for degenerative mitral regurgitation—analysis of factors affecting durability.Heart Lung Circ. 2019; 28: 1852-1865Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar]. I really do suspect that many surgeons in NSW are achieving successful repair of degenerative mitral valves well above what has been reported by Cheng et al. Of the 50 cardiac surgeons in NSW (2019), some 150 repairs were accomplished in the last year of the study in 571 mitral valve surgeries (2017). However, it would be in the public interest for surgeons to achieve acceptable rates of repair and/or to have at least two or three centres focussing on establishing genuine excellence in repairing the degenerative mitral valve. The consequences of subpar utilisation of mitral valve repair are profound in both economic and human costs. Economic costs include: a valve prosthesis is several thousand dollars more expensive than an annuloplasty ring, the length of stay is longer for replacement, and the aforementioned complications are more frequent; thus millions, if not tens of millions of dollars, are being consumed. The human costs are also challenging and troubling, depending on what one accepts as an acceptable repair percentage—by simple extrapolation, perhaps over one hundred lives could have been saved by performing mitral valve repair rather than replacement during hospital admissions, and hundreds more lives saved during the study time frame from reduced death, stroke, and endocarditis. Trends in Isolated Mitral Valve Repair or Replacement Surgery in Australia: A Statewide Cohort Linkage StudyHeart, Lung and CirculationVol. 33Issue 1PreviewGlobal trends in mitral valve surgery (MVSx) suggest increasing repair compared with replacement, especially in the United States and European countries. The relative use, and outcomes of, MV repair and replacement in Australia are unknown. Full-Text PDF Open Access
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