Ann Thorac Surg 2009;87:1143-1147. doi:10.1016/j.athoracsur.2008.12.041
© 2009 The Society of Thoracic Surgeons
Original Articles: Adult Cardiac
Midterm Survival After Decalcification of the Mitral Annulus
Nestoras Papadopoulos, MD*,
Marcus Dietrich, MD,
Triandafyllia Christodoulou,
Anton Moritz, MD, PhD,
Mirko Doss, MD
Department of Thoracic and Cardiovascular Surgery, Johann-Wolfgang-Goethe University, Frankfurt/Main, Germany
Accepted for publication December 12, 2008.
* Address correspondence to Dr Papadopoulos, Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University, Theodor Stern Kai 7, Frankfurt am Main, 60590, Germany (Email: nestoras.papadopoulos{at}gmail.com).
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Abstract
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Background: The aim of this study is to determine the midterm outcomes of patients who underwent decalcification and patch-reconstruction of the mitral annulus during mitral valve surgery in our department.
Methods: Between 1996 and 2004, a total of 81 consecutive patients with a mean age of 64 ± 13 years underwent mitral valve surgery in the presence of extensive calcification of mitral annulus. In the majority of cases (n = 42, 52%), a mitral valve repair was performed after decalcification and patch-reconstruction of the mitral annulus. The remaining 39 patients (48%) received a mitral valve prosthesis (biological n = 20, mechanical n = 19). Retrospective analysis of preoperative, operative, and postoperative information of these 81 patients was performed. The follow-up period ranged between 4 and 10 years (mean follow-up, 5.8 ± 3.1).
Results: The 30-day mortality was 8.7% (n = 7). The actuarial survival rates at 5 years were 79% ± 3%. At the latest follow-up, 34 patients (55.7%) were in New York Heart Association class I, 23 (37.7%) were in class II, and 4 (6.5%) were in class III. The freedom from reoperation at 5 years was 90.5% ± 2%. There was only 1 stroke (1.6%), which occurred 1 year after the operation.
Conclusions: These results show that despite the increased perioperative risk and the difficult approach of the pathology in this patient group, decalcification and patch-reconstruction of the mitral annulus during mitral valve surgery can be performed safely with satisfactory and stable clinical midterm results.
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Introduction
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Mitral valve calcification seems to occur as a manifestation of degenerative changes in the mitral leaflets and annulus and may be associated with mitral insufficiency, stenosis, prolapse, or conduction abnormalities. These changes are often encountered during mitral valve surgery and tremendously increase the complexity of the operation. The incidence of annular calcification increases with increasing age [1]. Owing to the advanced age of many of these patients, comorbidities such as chronic obstructive pulmonary disease, renal failure, peripheral vascular disease, stroke, and so forth, are also common and may independently increase perioperative risk and late mortality.
Although patients with severe mitral valve disease in the presence of extensive annular calcification constitutes a challenging cohort, en bloc decalcification, patch-reconstruction, and mitral valve repair or replacement have been shown to provide acceptable and stable long-term results [2–4]. The aim of this study is to determine the midterm outcomes of patients who underwent decalcification and patch-reconstruction of the mitral annulus during mitral valve surgery in our department.
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Patients and Methods
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Between 1996 and 2004, a total of 81 consecutive patients with extensive calcification of mitral annulus underwent mitral valve surgery. The patient cohort consisted of 51 women (63%) and 30 men (37%) whose mean age was 64 ± 13 years (range, 18 to 84). The study protocol was approved by the local Ethics Committee, and individual patient consent was waived. Retrospective gathering of preoperative, operative, and postoperative medical records of these patients was performed. Full data were obtained in all 81 patients.
Echocardiography and coronary angiography was performed in all patients preoperatively. Fifteen patients (18%) presented with mitral valve stenosis with moderate to severe symptoms, New York Heart Association (NYHA functional class III or greater. The mean mitral transvalvular gradient of these patients was 10 mm Hg or above. Sixty-six patients (82%) had a mitral insufficiency grade III and IV. The lesions responsible for the valve dysfunction are listed in Table 1. The mean preoperative ejection fraction was 64% ± 16%. The majority of the patients (n = 53, 65%) were in NYHA class III or IV. The remaining 28 patients (35%) were in NYHA class I or II. The mean preoperative left ventricular end-systolic diameter was 33 ± 11 mm, and the mean end-diastolic diameter was 58 ± 14 mm.
Nineteen patients (23%) had significant coronary artery disease. Twenty patients (25%) were in atrial fibrillation, 8 (10%) of whom had previous stroke. Six patients (7%) presented in atrioventricular block. The remaining 55 patients (68%) showed sinus rhythm. The medical history revealed arterial hypertension in 9 patients (11%), diabetes mellitus in 8 (10%), chronic obstructive pulmonary disease in 6 (8%), pulmonary hypertension in 14 (17%), and renal failure in 11 (14%). Preoperative patient characteristics are illustrated in Table 1.
Aortic valve reconstruction by decalcification was required in 1 patient. Other concomitant procedures included replacement of the aortic valve (n = 14, 17%) and tricuspid valve reconstruction for severe tricuspid regurgitation (n = 11, 14%). Table 2
illustrates all concomitant surgical procedures.
Operative Technique
Most of the patients (n = 74, 9%) were operated on through conventional median sternotomy; 3 patients (4%) were operated on through partial upper sternotomy and 4 patients (5%), through anterolateral thoracotomy (Chitwood technique). Our operative technique has been already described in detail in a previous publication [5]. The basic steps were as follows. Standard ascending aortic and bicaval venous cannulation was used. Cardiopulmonary bypass was performed with moderate hypothermia (32°C). After obtaining access to the mitral valve through the transseptal approach, the mitral leaflets and subvalvular apparatus were systematically examined. After the examination, the decision to replace or to repair the valve was taken. Decalcification was performed by incising the atrium around the borders of the calcium bar at the posterior leaflet. The calcified parts were resected en bloc with a scalpel and scissors, and the resulting defect of the atrioventricular junction was finally reconstructed with a strip of untreated autologous pericardium. In the majority of cases (n = 42, 52%), mitral valve repair was performed by quadrangular resection of the posterior mitral leaflet and ring annuloplasty. The annuloplasty ring was anchored in right and left trigones and its sutures passed through the pericardial patch.
Thirty-nine patients (48%) received a mitral valve replacement. Twenty patients (25%) received biological prostheses and 19 patients (23%), mechanical mitral valve prostheses. In this cohort, the posterior leaflet was completely excised, and the valve sutures were passed through the pericardial patch, fixing the proximal part of the patch to the left atrium. The mean cross-clamp time was 137 ± 33 minutes, and cardiopulmonary bypass time was 208 ± 33 minutes. Table 3
illustrates the perioperative data.
Statistical Analysis and Data Collection
Quantitative data are expressed as mean ± SD, as well as median and range. The incidence is given as percentages. Survival is presented using Kaplan-Meier curves. Follow-up information was collected between December 2007 and February 2008 by patient or physician contact. The mean follow-up time was 5.8 years and 3 months. Hospital mortality was defined as death within 30 days of operation.
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Results
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The hospital mortality was 8.7% (7 patients). There were 2 intraoperative deaths (2.5%), 1 as a result of a rupture of left ventricular free wall and 1 due to biventricular failure. Three patients died of low cardiac output syndrome and 2 of multiple organ failure. The mean intensive care unit stay and mean hospital stay are illustrated in Table 3. Postoperative complications are summarized in Table 4.
Follow-up echocardiography before discharge of the survivors showed a mean left ventricular end-diastolic diameter of 45 ± 24 mm and a mean left ventricular end-systolic diameter of 30 ± 21 mm. The postoperative ejection fraction was 50% ± 10%. The follow-up period was from 4 to 10 years and complete, with a mean follow-up time of 5.8 ± 3.1 years. There were 13 late deaths. The causes of death were left-side heart failure (n = 2, 2%), sudden death (n = 2, 2%), sepsis (n = 1, 1%), and cancer (n = 2, 2%). One more patient died after receiving a redo procedure. In 5 follow-up cases, it was impossible to report the precise cause of death. The actuarial survival rate at 5 years was 79% ± 3%. The Kaplan-Meier curve of survival after decalcification, patch-reconstruction of mitral valve annulus, and mitral valve surgery is illustrated in Figure 1.
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Fig 1. Long-term actuarial survival in 81 patients undergoing mitral valve repair/replacement with extensive calcification of the mitral annulus.
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At the latest follow-up, 34 patients (55.7%) were in NYHA class I, 23 (37.7%) were in class II, and 4 (6.5%) were in class III. Atrial fibrillation developed in 9 patients (14.7%) who were in sinus rhythm before the operation. Only 1 patient (1.6%) had a stroke, which occurred 1 year after the operation. Reoperations due to recurrent mitral valve regurgitation after mitral valve reconstruction were performed in 7 patients (8.6%), and another patient needed a redo procedure owing to a paraprosthetic leakage. All patients except the one who required the redo procedure survived. The actuarial reoperation-free rate at 5 years was 90.5% ± 2%. The Kaplan-Meier curve of freedom from reoperation of patients undergoing mitral valve surgery with an extensive degree of calcification of the mitral annulus is illustrated in Figure 2.
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Fig 2. Actuarial freedom from reoperation of patients undergoing mitral valve surgery in the presence of extensive calcification of the mitral annulus.
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Comment
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Mitral valve calcification seems to occur as a manifestation of degenerative changes in elderly persons, with an overall incidence of 2.8%. Among 81 patients who were included in this study, more than half (n = 51, 63%) were women whose mean age was 68 ± 12 years (range, 26 to 84). Our findings underline the common opinion that this pathology is found more frequently among elderly women, with a reported female:male sex ratio of 3:2 [2, 6, 7].
In addition to the fibroelastic deficiency present in elderly persons, severe Barlow's disease can be a further predisposing factor for the annular calcification, primarily in young adults, as described by Carpentier and colleagues [8, 9]. Of our patient cohort, 6% (n = 5) have a billowing mitral valve, but the majority of patients (90%, n = 73) presented with fibroelastic deficiency. Other causes of mitral valve calcification are rheumatic endocarditis (3% of our patient cohort, n = 3) and probably connective tissue disorders as in Marfan and Hurler syndromes [10, 11]. Fibrocalcific changes can also be seen in patients without any primary tissue disorders but with systemic hypertension and metabolic diseases [12, 13].
Recent studies support the hypothesis that mitral valve calcification arises from progressive degeneration of the annulus, including accumulation of lipids and disorientation of collagen fibers [14]. Many recent studies have shown that patients with mitral annulus calcification have a higher prevalence of carotid artery stenosis, coronary artery stenosis, and peripheral artery stenosis [15–17]. Thus, patients with mitral annulus calcification have an elevated risk profile, as expressed by an additive European System of Operative Cardiac Risk Evaluation score of 7 and a concomitant surgery rate of 62% in our study. Mitral annulus calcification can lead to a reduction of mitral leaflet mobility and elevation of leaflets, and thus enhances chordal elongation or rupture [8]. Thereby, a secondary mitral valve insufficiency can develop, necessitating mitral valve reconstruction or replacement.
Mitral valve surgery in the presence of extensive annular calcification remains a challenge for the surgeon, and calcification in the mitral annulus used to be referred to as "the bar of death." Therefore, patients with mitral annular calcification must be referred to the more experienced valve surgeons. In case that the surgeon is not comfortable with the reconstructive technique, it is better to proceed to the more straightforward mitral valve replacement. Characteristically, the calcification involves the posterior annulus, giving a radiologic and anatomic appearance of a semilunar structure (Figs 3 and 4).
In some cases, calcification may extend to the subvalvular apparatus or can be circumferential, incorporating additionally the anterior annulus. Sequelae of extensive debridement of those calcified mitral annuli can be heart block, injury of the circumflex artery, atrioventricular disruption, or ventricular rupture with a fatal outcome.
To approach the difficult problem of mitral valve surgery after decalcification, several techniques have been published, with varying results. Left ventricular rupture, hemorrhagic complications, and thromboembolic events can be associated with valve replacement in patients with extensive annular calcification [2–4]. To avoid these risks associated with mitral valve replacement, El Asmar and coworkers [18] described a technique of mitral valve repair in the extensively calcified mitral valve annulus. Mitral valve repair was performed by en bloc resection of the annular calcium deposits, and annular reconstruction was performed using pledgeted supported sutures, with good results. A reconstructive procedure with partial decalcification in the area of leaflet resection followed by repair and reconstruction of the mitral leaflet was described by Grossi and associates [19]. This technique is limited by the requirements of a repairable valve and calcification that must not be extensive. Radical decalcification results mostly in poor quality tissue for holding sutures and atrioventricular fistula. In these cases, mitral annulus reconstruction has to be performed with either fresh autologous pericardium or glutaraldehyde-fixed bovine pericardium. In 1986, Carpentier [20] introduced a technique of annulus reconstruction for extensive mitral annulus calcification. This technique has considerably increased the possibilities of mitral valve reconstruction after extensive decalcification. In an actuarial publication, Carpentier and colleagues [8] showed that complete annulus decalcification and valve repair can be done safely with good long-term results (survival rate to 7 years, 93.1% ± 7.5%). Nevertheless, fibrotic calcified and immobile leaflets or calcification of the whole annulus and deformed subvalvular apparatus are generally considered as contraindications to mitral valve repair. In those cases, mitral valve replacement has to be performed.
The preferred technique in our series was reconstruction of the mitral valve, as left ventricular function improves over the long term when the native valve is preserved [21]. Further reasons for our preference for mitral valve repair were the decreased operative mortality rate and the better long-term survival after mitral valve reconstruction that have also been reported in previous studies [22–24]. Furthermore, Enriquez-Sarano and coworkers [22] showed that although mitral valve repair does not reduce the incidence of valve failure, it is univariately associated with a lower incidence of postoperative congestive heart failure due to myocardial failure. Mitral valve reconstruction was achieved in 42 of our patients (52%). Mitral valves were repairable when leaflets were spared from calcifications and when the subvalvular apparatus was not calcified.
Our approach involving aggressive and complete annulus decalcification and reconstruction of the mitral annulus by pericardial patch showed acceptable both short- and long-term results. In our series, the hospital mortality was 8.7% (7 patients), which was similar to the mortality reported in previous studies [19, 25, 26]. Our midterm follow-up showed actuarial survival rates at 5 years of 79% ± 3%. Feindel and coworkers [25] reported survival rates at 5 years of 78% ± 6% in a series of 54 patients with severe calcification of the mitral annulus who underwent mitral valve surgery and reconstruction of mitral annulus using the same technique. In our series, 93.4% of the survivors are currently in NYHA class I or II. Despite the high risk of heart block after a severe mitral valve decalcification, the incidence of permanent heart block in our study was low (n = 3, 3.7%). This, however, is not a universal finding [25]. The freedom from reoperation reported in literature varies from 87.1% ± 10.6% [4] to 91% ± 5% [25] at 9 and 8 years, respectively. We can confirm these results. In our series, the freedom from reoperation due to valve-related causes at 5 years was 90.5% ± 2%.
In conclusion, it appears from our data that patients with severe mitral valve disease with extensive calcification of the annulus represent an elderly and challenging group of patients who have many comorbidities. We found that despite an increased perioperative risk and the difficult approach to the pathology in this patient group, decalcification, patch-reconstruction of the mitral annulus, and mitral valve surgery (mitral valve reconstruction/replacement) can be safely performed with satisfying and stable clinical midterm results.
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Abstract
Introduction
