Early and long-term results of mitral valve repair for mitral regurgitation due to isolated posterior leaflet prolapse - Tran Ngoc Vu

Journal of military pharmaco-medicine n o 7-2018 177 EARLY AND LONG-TERM RESULTS OF MITRAL VALVE REPAIR FOR MITRAL REGURGITATION DUE TO ISOLATED POSTERIOR LEAFLET PROLAPSE Tran Ngoc Vu*; Le Ngoc Thanh** SUMMARY Objectives: To evaluate the long-term results of mitral valve repair in patients with mitral regurgitation caused by isolated posterior leaflet prolapse at Danang Hospital. Subjects and methods: A retrospective, descriptive study combined with a prospective study. Thirty two patients with chronic severe mitral regurgitation due to isolated posterior leaflet prolapse were treated by new surgical techniques in Danang Hospital from February 2010 to October 2017. Preoperative, pre-discharge and follow-up findings were recorded. Postoperative echocardiography was performed in all patients at predischarge and during clinical follow-up. Late survival and freedom from adverse events including hemorrhage, endocarditis, reoperation, and residual severe mitral regurgitation were estimated by using the Kaplan-Meier survival analysis. Results: Ages ranged from 12 to 68 years (mean 43.06 ± 15.78 years). According to New York Heart Association (NYHA) functional classification: 3.12% (1/32) of patients were in class I; 90.63% (29/32) were in class II; 6.25% (2/32) were in class III, and no patient was in class IV; 32 patients (100%) had severe mitral valve regurgitation (3+). Twenty- six patients were treated by triangular resection of posterior leaflet; five patients by chordal replacement and one patient by both techniques. Echocardiography was carried out in all patients before discharged from hospital; 96.88% of patients had no or mild regurgitation, and 3.12% of patients had moderate regurgitation (2+), no one had severe regurgitation; no in- hospital mortality. Late mortality occurred in only one patient at 3 months after discharge because of severe heart failure. The mean follow-up time of patients was 36.44 ± 26.09 months (from 3 to 94 months), all the 31 surviving patients were in NYHA class I. Echocardiographic examination during follow-up revealed that mitral insufficiency was none or mild (≤ 1+) in 100% of patients. No patient had moderate or severe mitral regurgitation. Kaplan-Meier survival analysis estimates were 96.9 ± 3.1% for late survival and 96.9 ± 3.1% for freedom from recurrent severe mitral regurgitation at 7 years. Conclusion: Mitral repair for mitral regurgitation due to isolated posterior leaflet prolapse is a feasible and safe procedure with an excellent surgical long-term outcomes. * Keywords: Mitral valve; Isolated posterior prolapse mitral regurgitation; Mitral repair. INTRODUCTION Mitral regurgitation (MR) is a very common valvular disease. Surgical treatment improves patients' prognosis and quality of the life [1]. Posterior leaflet prolapse is the most common lesion seen in degenerative mitral valve disease [2]. Quadrangular resection, first proposed by * Danang Hospital ** Hanoi E Hospital Corresponding author: Tran Ngoc Vu (tngocvu@gmail.com) Date received: 10/07/2018 Date accepted: 30/08/2018 Journal of military pharmaco-medicine n o 7-2018 178 Alain Carpentier, has progressed to become the gold standard modality to repair posterior leaflet prolapse. Although this “resection technique” is safe, reproducible, and offers favorable long- term results, it presents major drawbacks [3]. Tri-angular leaflet resection of the mitral valve produces durable results and can be safely and efficiently performed with minimal morbidity and mortality [4]. The use of artificial chordae to correct the leaflet prolapse restores the normal anatomy and physiology of the mitral valve, thus producing an optimal surface of coaptation [3]. Our research aims to: Evaluate the long-term results of mitral valve repair in patients with mitral regurgitation caused by isolated posterior leaflet prolapse. SUBJECTS AND METHODS 1. Subjects. This study was carried out at Danang Hospital from February 2010 to October 2017. Thirty-two consecutive patients with chronic severe MR due to isolated posterior leaflet prolapse underwent mitral valve repair. Patients with tricuspid insufficiency were included. 2. Methods. Retrospective combined with prospective study, cross-sectional descriptive analysis without control group. * Preoperative assessment: Clinical assessment by NYHA class. Severity of MR was defined by Doppler echocardiography (grade 1+, 2+, 3+, and 4+) by semiquantitative method. The etiology of MR was identified by surgeon during operation. * Surgical indications: Indications for mitral surgery, as expressed in the guidelines, were based on levels of evidence B [5]. * Surgical technique: All operations were performed through a full median sternotomy and under cardio-pulmonary bypass with ascending aortic and bicaval canulation and aortic cross-clamping for the entire valve repair time. Myocardial protection was accomplished with intermittent cold blood cardioplegia given down the aortic root. The mitral valve was exposed through transseptal or left atrial approach. The mitral valve was then inspected in detail and the prolapsed area was identified. We used the triangular resection and chordal replacement techniques or combined both techniques for repair the prolapsed area of posterior leaflet. Finally, a complete flexible ring or a pericardial band was applied for mitral annuloplasty. * Postoperative assessment: All patients had a transthoracic echocardiography study before hospital discharge. Follow-up investigations included clinical examination, electrocardiography, and Doppler echocardiography. Doppler echocardiography was carried out every 3 months in the first postoperative year and every 6 months thereafter. Results were recoded at the latest follow-up examination. Journal of military pharmaco-medicine n o 7-2018 179 * Statistical analysis: Descriptive statistics are reported as the mean ± standard deviation for continuous variables and compared by a student t-test or Wilcoxon Signed Ranks test. Categoric variables are reported as frequencies and percentages and were compared using Chi-square tests. For statistical analysis, the statistical software SPSS version 22.0 for Windows was used, and p value less than 0.05 was considered statistically significant. RESULTS 1. Preoperative and intraoperative characteristics. Table 1: Preoperative baseline characteristics. Variable Value Age (year) 42.84 ± 15.83 Gender (male/female) 24/8 NYHA functional status: NYHA I 3.12% NYHA II 90.63% NYHA III 6.25% Atrial fibrillation 21.88% Cardiothoracic ratio 0.57 ± 0.07 Mean systolic pulmonary arterial pressure (mmHg) 53.13 ± 15.12 Mean left ventricle end-systolic diameter (mm) 35.97 ± 6.40 Mean left ventricle end-diastolic diameter (mm) 58.91 ± 7.70 Mean left atrium diameter (mm) 46.63 ± 9.41 Mean ejection fraction (%) 67.41 ± 8.31 Grade 3 MR (3+) 100% There were 24 men (75.0%) and 8 women (25.0%). Mean age ranged from 12 to 68 years (mean age 43.06 ± 15.78 years). The patients were of NYHA functional class I 3.12%, class II 90.63%, class III 6.25%, and no patient in class IV. The cardiothoracic ratio ranged from 0.45 to 0.66 (mean 0.57 ± 0.07). 100% of patients had severe MR (grade 3+) on Doppler echocardiograhy. * Etiology of MR: The most frequent cause of non- ischemic structural MR was degenerative mitral valve disease (24 patients = 75.0%), and low incidence was rheumatic valvular disease (1 patients = 3.12%). Other etiology was endocarditis (4 patients = 12.5%) and congenital (3 patients = 9.38%). Journal of military pharmaco-medicine n o 7-2018 180 Table 2: Procedures. Procedures No. of patients % Ring annuloplasty 31 96.88 Posterior annuloplasty band 1 3.13 Triangular resection of posterior leaftet 26 81.25 Chordal replacement 5 15.63 Triangular resection and chordal replacement 1 3.13 Tricuspid annuloplasty 6 18.75 Coronay artery bypass graft 1 3.13 Table 2 describes the predominant repair technique for isolated posterior leaflet prolapse. Triangular resection was the most common technique in our series (81.25%) and the annulus dilatation was treated with prosthetic ring remodeling annuloplasty in 31 patients (96.88%). Prosthetic ring sizes ranged from 26 to 32 (mean 29.42 ± 1.57). Chordal replacement in 15.63% and one patient having a combination of both leaflet resection and chordal implanted (3.13%). Concomitant operation performed was tricuspid valve repair in 6 patients (18.75%). 2. Before discharge results. Table 3: Early postoperative results. Outcome Value Intensive care unit stay (day) (mean) 2.16 ± 1.25 Hospital stay (day) (mean) 11.03 ± 3.57 Neurological complications 0,0% Mediastinitis 0,0% Acute renal failure 0,0% Low cardiac output syndrome 6.25% Surgical site infections 6.25% Pneumonia 3.12% Central venous catheter infection 3.12% MR severity: None to 1+ MR 96.88% 2+ MR 3.12% In-hospital mortality 0,0% The mean hospital stay was 11.03 ± 3.57 days (range 6 - 22 days). The mean intensive care unit stay was 2.16 ± 1.25 days (range 1 - 6 days). The postoperative complications were low in our series. Journal of military pharmaco-medicine n o 7-2018 181 All patients had undergone a postoperative pre-discharge transthoracic echocardiography, 96.88% of patients had no or mild regurgitation and 3.12% of patients had moderate regurgitation (2+), no one had severe regurgitation; no in- hospital mortality. 3. Long-term results. Table 4: Long-term postoperative results. Variable Preop (n = 32) Postop (n = 31) p NYHA class: NYHA I 3.13% 100% NYHA II 90.63% 0,0% NYHA III 6.25% 0,0% NYHA (mean) 2.03 ± 0.31 1.0 ± 0.0 < 0.05 Electrocardiographic findings: Sinus rhythm 78.12% 96.77% Atrial fibrillation 21.88% 3.23% < 0.05 Echocardiographic findings: LVESD (mm) 35.97 ± 6.40 31.10 ± 5.23 LVEDD (mm) 58.91 ± 7.70 47.06 ± 6.60 LAD (mm) 46.63 ± 9.41 34.68 ± 11.34 SPAP (mmHg) 53.13 ± 15.12 30.65 ± 2.15 < 0.001 Grade MR on echocardiography: 1+(1/4) 0.00% 100% 2+(2/4) 0,0% 0,0% 3+(3/4) 100% 0,0% Grade (mean) 3.0 ± 0.0 1.0 ± 0.0 < 0.001 (LVESD: Left ventricular end-systolic diameter; LVEDD: Left ventricular end-diastolic diameter; LAD: Left atrial diameter; SPAP: Systolic pulmonary artery pressure; EF: Ejection fraction; MR: Mitral regurgitation) Table 4 summarizes the preoperative and long-term postoperative data of mitral valve repair. The mean follow-up period of patients was 36.44 ± 26.09 months (from 3 to 94 months). No patient need to reoperation, no patient had anticoagulation related hemorrhage and endocarditis during the follow-up. Late mortality occurred in only one patient at 3 months after operation because of severe heart failure due to severe recurrent MR. All the 31 surviving patients were in NYHA class I. Echocardiographic examination during follow-up revealed that mitral insufficiency was none or mild (≤ 1+) in 100% of patients. Journal of military pharmaco-medicine n o 7-2018 182 DISCUSSION Mitral regurgitation is a very common valvular disease. Mitral repair is a method of choice in treatment of significant MR [1]. Mitral valve repair techniques were pioneered by Alain Carpentier with a rigid annuloplasty ring in his publication the “French Correction” [6]. Surgical techniques have continuously developed over the past five decades [7]. There are many techniques to correct the prolapsing leaflet, and there has been a move away from the traditional posterior leaflet resection (quadrangular resection/sliding technique) to leaflet preservation techniques with Gore-Tex neochordae [8]. The classic quadrangular resection technique became the gold standard for isolated posterior leaflet prolape. This method has several disadvantages like lack of height of leaflet coaptation, deformation of the sub-annular region of the left ventricle and the risk of king-king of the circumflex artery. Triangular resection reduced some disadvantages of quadrangular resection. In our practice, no quadrangular resections were employed. We relied mostly on triangular resections of posterior leaflet (81.25%). It is quicker and easier to perform than standard quadrangular resection. Chordal replacement has also been used occasionally to correct the prolapse of the posterior leaflet (15.63%). On the other hand, in the case, after the greatest area of prolapse is resected, there still remains areas of chordal elongation where the posterior leaflet requires additional artificial chordae support (3.12%). George K.M et al [9] reported that triangular resection represents a simple and effective technique for the management of segmental posterior leaflet prolapse. Ibrahim M et al [10] concluded that the clinical outcomes of artificial chordae for the repair of the mitral valve are comparable with classical techniques and it may have some physiological advantages and provides a good long-term results. Our study demonstrates that the both techniques (triangular resection and neochord replacement) for isolated posterior leaflet prolapse repair had excellent results with 100% of patients having none or mild (≤ 1+) MR and no adverse complications after operation. CONCLUSION Isolated posterior leaflet prolapse is the most common lesion seen in degenerative mitral valve disease. Triangular posterior leaflet resection is an easy, effective and durable method for correcting posterior leaflet prolapse. Artificial chordal replacement has been shown to be effective and durable outcomes too. The combination of triangular resection and annuloplasty is an excellent option for mitral valve repair in most patients with isolated posterior leaflet prolapse. REFERENCES 1. Němec P, Ondrášek J. Surgical treatment of mitral regurgitation. Cor Vasa. 2017, 59 (1), pp.e92-e96. 2. Varghese R, Adams D.H. Techniques for repairing posterior leaflet prolapse of the mitral valve. Oper Tech Thorac Cardiovasc Surg. 2011, 16 (4), pp.293-308. Journal of military pharmaco-medicine n o 7-2018 183 3. Perier P, Hohenberger W, Lakew F et al. Prolapse of the posterior leaflet: Resect or respect. Ann Cardiothorac Surg. 2015, 4 (3), pp.273-277. 4. Gazoni L.M, Fedoruk L.M, Kern J.A et al. A simplified approach to degenerative disease: Triangular resections of the mitral valve. 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