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Eur J Cardiothorac Surg 2003;23:552-559
© 2003 Elsevier Science NL
a Cardiac Surgery Department, National Research Council, Ospedale G. Pasquinucci CNR-CREAS, v Massa, Italy
b Cardiovascular Department, Ospedali Riuniti, Bergamo, Italy
Received 5 September 2002; received in revised form 16 December 2002; accepted 22 December 2002.
* Corresponding author. Tel.: +39-0585-4936-04; fax: +39-0585-4936-14
e-mail: bevilacqua{at}ifc.cnr.it
| Abstract |
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3+/4+ was significantly higher in the prosthetic ring group (90.1% CL90%: 81.998.3%) compared with the pericardial ring group (62.6% CL90%: 43.182.1%; P=0.027). Prosthetic ring implantation (P=0.004; RR=0.11) and preoperative New York Heart Association (NYHA) class
II (P=0.011; RR=0.16) were independently related to a lower risk of reoperation and recurrence of mitral regurgitation
3+/4+, by multivariate analysis. Five-year overall survival was 91.4% (CL90%: 87.9.795%). A higher preoperative left ventricular end-diastolic diameter (P=0.006; RR=1.17) and the severity of associated coronary artery disease (P=0.021; RR=2.00) were independent predictive factors for poor survival by multivariate analysis. Conclusions: Posterior pericardial annuloplasty can jeopardize reproducibility and durability of MVR for degenerative regurgitation.
Key Words: Mitral valve repair Pericardial ring annuloplasty Reoperation
| 1. Introduction |
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Therefore, we compared the durability of PPA with prosthetic ring annuloplasty in a group of consecutive patients undergoing MVR for degenerative mitral regurgitation at our institution.
| 2. Patients and methods |
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2.2. Preoperative assessment
The medical charts of the patients fulfilling the inclusion criteria were retrospectively reviewed and processed in a structured database, consisting of demographic data, preoperative clinical data, echocardiographic parameters, operative and postoperative data. All patients received transthoracic echocardiography and cardiac catheterization with selective coronary angiography before the operation. Intra-operative trans-esophageal echocardiography (TEE) was routinely performed to confirm the pathology and assess the repair outcome.
2.3. Surgical procedure
Standard moderate hypothermic (2832°C) cardiopulmonary bypass with aortic and bicaval cannulation was used in all cases, with a conventional approach through a median sternotomy. Antegrade hyperkalemic tepid blood cardioplegia was administered at 15-min intervals. There were only two operating surgeons. The surgical repair was accomplished with the "French correction" technique, as described by Carpentier and colleagues, exposing the valve through a left atriotomy [4]. Chordal replacement with Gore-Tex sutures was not performed in any case. Chordal transposition, chordal shortening by embedding chordae into the papillary muscle (Carpentier technique) or by papillary muscle sliding plasty (Duran technique), were all used to correct anterior leaflet prolapse. Prosthetic ring annuloplasty was performed with CarpentierEdwards Classic and CarpentierEdwards Physio ring implantation (Baxter Healthcare Corp., Deerfield, IL, USA). PPA was performed with a gutaraldehyde-treated strip of autologous pericardium, as previously described [9,10]. Just after sternotomy a rectangular patch of autologous pericardium (about 4x5 cm2) was harvested, cleaned of adipose tissue and fixed in a 0.65% glutaraldehyde-buffered solution for 15 min. Afterward it was rinsed with saline solution for 15 min in three separate bowls. Just before implantation, a pericardial ring (0.50.7 cm wide, C-shaped strip) was cut from the patch. Pericardial ring length was proportioned to the anterior leaflet free edge extension by means of Carpentier obturators. The size of the Carpentier obturator, used for pericardial ring modeling, was properly selected according to patient's body surface area (BSA). The size was determined according to the following rules: 30 mm obturator for BSA
1.5 m2; 32 mm obturator for BSA ranging from 1.6 to 1.8 m2; 34 mm obturator for BSA ranging from 1.8 to 2 m2; 36 mm obturator for BSA >2 m2. The pericardial ring was fixed with mattress sutures along the posterior annulus, just beyond the anatomic commissures.
Annuloplasty techniques varied during the study period and in most of cases the choice was not patient-related. Since August 1995 through June 1997, the CarpentierEdwards Classic ring was the device of choice (20/26 patients 76.9%). Afterward, from July 1997 to April 1999, the procedure of choice was PPA (47/60 patients 78.3%). In the last period, from May 1999 through December 2000 we implanted mostly CarpentierEdwards Physio rings (37/47 patients 78.7%). There was a significant difference, among the three periods, regarding the distribution of different annuloplasty techniques (P<0.0001).
2.4. Postoperative outcomes and follow-up
Operative death was defined as any death occurring within 30 days after surgery, without any regard for the place where it occurred. Postoperative complications were defined according to current guidelines [17]. All patients received a transthoracic echocardiography before hospital discharge. Follow-up was conducted during a 2-month interval ending in February 2002 by telephone interview and visit, including physical examination and echocardiography.
Deaths attributed to acute myocardial infarction (AMI), congestive heart failure (CHF), arrhythmia and sudden deaths without any other specific cause were considered as cardiovascular deaths. Deaths related to acute endocarditis were also deemed as cardiovascular deaths. Cause of death was established from hospital charts, autopsy reports when available or from a family physician interview. Non-fatal complications such as AMI, stroke, thromboembolism, anticoagulation-related hemorrhage, endocarditis and CHF episodes were all recorded at follow-up.
2.5. Echocardiography
Two-dimensional and Doppler echocardiography was performed using a Sonos 5500 ultrasound system (HewlettPackard). Left ventricular ejection fraction (LVEF) was assessed by the volumetric method [18]. Left ventricular end-diastolic (LVEDD) and end-systolic (LVESD) diameters were calculated by M-mode measurements, guided by 2D images. The grade of mitral regurgitation was evaluated with color-Doppler, using a four-grade, semi-quantitative scale according to the extension of the regurgitant jet in relation to the left atrium [19]. Mitral valve area was calculated by Doppler echocardiography using the pressure half time method.
Functional and segmental mitral valve analysis were carried out by intraoperative TEE. The risk of systolic anterior motion (SAM) was estimated on the basis of mitro-aortic angle and the ratio of the mitral valve annulus diameter to the anterior mitral leaflets length [20]. TEE was repeated at the end of repair to assess the grade of residual mitral insufficiency and evaluate the occurrence of SAM.
2.6. Statistical analysis
Categorical variables were compared between groups by the
2 test for independence or by the Fisher's exact test, when appropriated. For the comparison of continuous variables, independent samples t-test was performed when the variable distribution was found to be normal by the KolmogorovSmirnov test, otherwise a non-parametric MannWhitney test was used. Group data were summarized by mean and standard deviation (SD) or by frequency percentages. Confidence limits of percentages were computed by means of a quadratic approximation to binomial distribution and continuity correction. Overall survival and freedom from reoperation were estimated by KaplanMeier analysis. Comparison between unadjusted overall group survival and freedom from reoperation and mitral regurgitation
3+/4+, relative to baseline characteristics, were assessed by the logrank test. The multivariate relationships of potential predictive factors for late death, for reoperation and mitral regurgitation
3+/4+ were evaluated by multivariable Cox regression analysis. Those variables with an univariate P value
0.1 or those of known biological significance but failing to meet the critical
level were submitted for consideration to multivariable Cox analysis. A stepwise technique was used to enter the selected variables in the analysis. Variables included in the multivariable analysis are listed in Appendix A.
Statistical analysis was performed with StatView software version 5.0.1 (SAS Inc., Cary, NC, USA).
| 3. Results |
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3.2.1. Durability of the repair
Eleven patients required reoperation for recurrent mitral regurgitation at 16.7±15.6 months, with no operative deaths (prosthetic ring group 2/74 2.7%; pericardial ring group 9/54 16.7%: P=0.005). Most of these patients underwent mitral valve replacement but in two cases a re-repair was feasible. Most of repair failures were procedure-related (Table 5). In the pericardial ring group the most frequent finding at reoperation was suture dehiscence of posterior annulus plication and posterior leaflet reconstruction with partial ring detachment (Table 5). Five-year freedom from reoperation was 95% (CL90%: 90.699.4%) for the prosthetic ring group and 79.5% (CL90%: 71.887.2%) for the pericardial ring group (P=0.016).
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Five-year freedom from reoperation and recurrence of mitral regurgitation
3+/4+ was significantly higher in the prosthetic ring group (90.1% CL90%: 81.998.3%) compared with the pericardial ring group (62.6% CL90%: 43.182.1%; P=0.027) (Fig. 1a
). Prosthetic ring implantation and preoperative NYHA class
II were independently related to a lower risk of reoperation and recurrence of mitral regurgitation
3+/4+, by multivariate analysis (Table 6). The operating surgeon had no influence on repair durability (P=0.706).
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There was a significant reduction of LVEDD (mean difference=7.8 mm CL90%: 6.98.7 mm; P<0.0001) and LVESD (mean difference=7.3 mm CL90%: 6.48.2 mm; P<0.0001) at follow-up, compared with preoperative values. On the contrary, LVEF at follow-up (56.1±8.4%) was unchanged compared with preoperative values. A significant reduction of left atrium dimension was also observed (mean difference=8.8 mm CL90%: 7.510.2 mm; P<0.0001). There were no differences between the groups in terms of LVEDD, LVESD and LVEF variation at follow-up.
Mitral valve area was 2.8±0.3 cm2 with no difference between the two groups. At follow-up no patients showed SAM with significant LVOT obstruction.
Thirteen patients among 30-day survivors had non-fatal complications requiring hospitalization during follow-up. One patient (0.8%) had AMI, three patients (2.5%) had a stroke, one patient (0.8%) had peripheral thromboembolism, three patients (2.5%) had anticoagulation-related hemorrhage, and five patients (4.2%) had CHF.
Event-free survival at 5 years (freedom from death, reoperation or MR
3+/4+, endocarditis, thromboembolism, stroke, hemorrhage, CHF and AMI) was 60.6% (CL90%: 50.570.8%), with no difference between the two groups (prosthetic ring group: 66.2%; CL90%: 53.878.7% PPA group: 50.4%; CL90%: 32.668.1%; P=0.484), as showed in Fig. 1c.
| 4. Discussion |
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Several annuloplasty techniques have been described with the support of both prosthetic and biological devices. Up to date, the ideal annuloplasty ring is a matter of debate. PPA, introduced by Salati and coworkers [9], has been shown to provide more physiological mitral annulus dynamics and to preserve ventricular performance during stress, compared to rigid prosthetic rings [11], with 5-year freedom from reoperation of 89.7%. In a large retrospective study Gillinov and coworkers [1] found that, even if failure to add an annuloplasty to posterior leaflet resection increased the risk of late reoperation, the type of annuloplasty (prosthetic ring or PPA) did not show any impact on long-term durability of repair. Nevertheless, in the same article, it is noteworthy that the Cleveland group, during the last years, did not perform PPA, but preferred prosthetic ring annuloplasty as the procedure of choice [1]. On the other hand, Lorusso and colleagues found that PPA was independently related to late repair failure in patients who underwent double orifice MVR [12]. The current study identified PPA as an independent risk factor for MVR failure and reoperation, confirming the results of previous reports [12,13]. In our opinion the use of autologous pericardium does not provide a sufficiently stable and durable fixation and remodeling of the annulus that, by worsening leaflet coaptation, directly contributes to the reoccurrence of mitral regurgitation. Furthermore, as previously demonstrated in an animal model for double orifice repair [22], the absence of a stable annular support could indirectly increase the systolic stress on the repaired structures (transposed or shortened chordae, reconstruction of posterior leaflet resection, etc.), leading to an increased risk of procedure-related failures. This concept, that relates annular diameter and shape with tension on leaflets edges, and consequently, on repair sutures, was confirmed with a mathematical model by Arts et al. [23]. Previous reports by Gillinov et al. [1,24], including also patients treated with PPA, showed that 3070% of MVR failures for degenerative disease were procedure-related, with 1022% of cases due to suture dehiscence of annuloplasty ring or posterior leaflet repair site. Chauvaud et al. [25] analyzing 73 reoperations after MVR with Carpentier rings, similarly found 11 cases (15.1%) of prosthetic ring dehiscence. In our series nine of 11 late failures (81.9%) were procedure-related and eight of these (88.9%) were observed in patients who underwent PPA. In the pericardial ring group five of nine (55.6%) reoperated patients showed partial suture dehiscence of ring or posterior leaflet reconstruction, whereas no patients in the prosthetic ring group showed these findings at reoperation. Although the small number of analyzed patients and some particular aspects of our PPA technique could limit the value of our results, it is conceivable to rise some doubts about durability, and especially, reproducibility of PPA. As underlined by Gillinov et al. PPA does not permit to achieve "a measured plication" of the mitral annulus and for this reason, in the last years, they actually abandoned this technique in favor of flexible prosthetic ring annuloplasty [1,24].
The present analysis did not endorse the theoretical advantages of PPA related to the avoidance of foreign material implantation; the type of implanted ring had no impact on endocarditis and thromboembolism incidence. Even if no data are available, it is reasonable that flexible prosthetic rings can offer similar advantages in term of mitral annulus dynamics compared to PPA. Consequently, we have drastically reconsidered the role of PPA in MVR for degenerative disease, moving to CarpentierEdwards Physio ring as the annular support of choice.
4.2. Late survival
Adjunctive results concerning the correlation between higher preoperative NYHA class and increased risk of reoperation, together with the negative prognostic impact of larger preoperative LVEDD on late survival clearly confirm the importance of early indication for surgery in improving long-term outcome of MVR for degenerative disease, as currently recommended. Furthermore, our report showed that the association of CAD has an important impact on long-term survival of patients with degenerative mitral disease.
4.3. Limitations of the study
The present study is a retrospective review of the clinical outcome of MVR at a single institution. The kind of implanted annuloplasty ring was not randomly assigned but varied during the study period. Thus, it must be taken into account that biases related to the learning curve could have influenced the results. The etiology of mitral valve disease was not supported by operative specimen histopathology, and this could have introduced confounding heterogeneity of the study population. Furthermore, technical aspects regarding glutaraldehyde fixation (time and concentration), pericardial ring modeling and implantation could be related to the unsatisfactory durability of PPA shown by our results. The follow-up time could be too short and the study population not large enough to reach a conclusive assessment of the two different techniques.
| 5. Conclusions |
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| Acknowledgments |
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| Appendix A |
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A.1. Preoperative data
Age, gender, preoperative NHYA class, hypertension, diabetes, peripheral vascular disease, preoperative serum creatinine
2 mg/dl, chronic obstructive pulmonary disease, preoperative atrial fibrillation, chronic heart failure, associated CAD, preoperative LVEF, preoperative left ventricular diameters, preoperative annulus diameter (echocardiographic data), anterior leaflet prolapse, annular calcification.
A.2. Operative and postoperative data
Operating surgeon, associated tricuspid valve repair, associated CABG, type of annuloplasty, chordal shortening (Carpentier technique), chordal transposition, papillary muscle sliding plasty, sliding leaflet repair, annular decalcification, mitral regurgitation at hospital discharge.
| References |
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