Preservation of the chordopapillary apparatus is mandatory

Mitral Valve Replacement With and Without Chordal Preservation in a Rheumatic Population: Serial Echocardiographic Assessment of Left Ventricular Size and Function Ujjwal K. Chowdhury, MCh, A. Sampath Kumar, MCh, Balram Airan, MCh, Dinesh Mittal, MS, K. Ganapathy Subramaniam, MS, Ram Prakash, DM, Sandeep Seth, DM, Rajvir Singh, MSc(Stat), PhD, and Panangipalli Venugopal, MCh Departments of Cardiothoracic and Vascular Surgery, Cardiology, and Biostatistics, Cardiothoracic Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India Background. The aim of this study is to investigate the feasibility of chordal-sparing mitral valve replacement procedures in a rheumatic population, and to determine the early and late effects of different chordal preservation procedures on the clinical outcome and left ventricular mechanics. Methods. Various techniques of chordal preservation during mitral valve replacement for rheumatic heart disease in 451 patients between 1996 and 1999 are described. The mean age was 35.6 19.0 years (range, 15 to 55 years). Seventy patients had complete excision of the subvalvular apparatus (group I), 124 had preservation of the posterior chordopapillary apparatus (group II), and 257 had total chordal preservation (group III). Echocardiography was performed preoperatively, at discharge, at 1 year, and at 4 years. Results. Chordal preservation groups (II and III) demonstrated significant improvement (p < 0.05) in left ventricular function immediately and late postoperatively. Reduction of left ventricular end-systolic and end-diastolic volume was significant in the chordal preservation groups (II and III) as compared to the nonchordal group (group I; p < 0.005). The total chordal group demonstrated greater fractional change of left ventricular end-systolic volume as compared to the posterior chordal and nonchordal group. The left ventricular ejection fraction and fractional shortening continued to decline over time in the nonchordal cohort (p 0.05 and p 0.001, respectively) and did not improve by 4 years. Statistically significant change in ejection fraction occurred in the chordal preservation groups as compared to the nonchordal group. Conclusions. We conclude that total chordal preservation is possible in the large majority of rheumatic patients and confers significant long-term advantage by preserving left ventricular function. The surgical technique should be individualized. (Ann Thorac Surg 2005;79:1926 33) 2005 by The Society of Thoracic Surgeons Preservation of the chordopapillary apparatus is mandatory in patients undergoing mitral valve replacement (MVR). Between 1996 and 1999, we used different chordal preservation techniques during MVR on an individualized basis. The possibility of prosthetic valve entrapment by the retained subvalvular apparatus, creation of left ventricular outflow tract obstruction (LVOTO), and implantation of a smaller sized prosthesis for the patient have been of major concerns to all investigators advocating the chordal-sparing MVR [1 5]. This prospective, nonrandomized study was designed to evaluate the immediate and late effects of different chordal preservation techniques on the clinical outcome and left ventricular size and function. Accepted for publication Oct 4, 2004. Address reprint requests to Dr Chowdhury, Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India; e-mail: ujjwalchow@rediffmail.com. Patients and Methods Assessment of the Mitral Valve and Selection Criteria for Chordal Preservation Decision to perform mitral valve surgery was made by physicians and was based on clinical, echocardiographic, and angiocardiographic criteria. Intraoperative transesophageal echocardiography was performed on all patients using a Hewlett-Packard Sonos 1500 or 5500 ultrasound system (Hewlett-Packard Co, Andover, MA). We attempted valve repair whenever possible [6]. The following criteria were taken into consideration for MVR with or without chordal preservation. 1. If the valve was heavily calcified or considered unsuitable for valve repair due to extensive scarring, shortening with severe subvalvular fusion, MVR was performed. 2. In patients who had undergone previous closed mitral valvotomy or mitral valve repair, MVR was preferred. 2005 by The Society of Thoracic Surgeons 0003-4975/05/$30.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2004.10.029

Ann Thorac Surg CHOWDHURY ET AL 2005;79:1926 33 MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 1927 Fig 1. Bar graph showing the number of each type of operation for each year of the study. (Black bar group I; grey bar group II; white bar group III.) 3. Conventional MVR was considered when the leaflets and subvalvular apparatus were thick with fusion of chordae tendinae and foreshortening of the chordal apparatus. All tissue had to be resected to allow the implantation of an appropriate sized valve for any given patient. The majority of patients in this group had predominantly stenotic lesions. 4. If the condition of the valve leaflet and subvalvular tissue was deemed worthy of preservation, every attempt was made to ensure that the preserved chordopapillary apparatus allowed implantation of an appropriate sized prosthesis and did not interfere with prosthetic valve function or create LVOTO. 5. Calcified mitral leaflets with annular extension were dealt with by squeezing or milking out the calcified debris from the annulus, segmental excision of the calcified segment with the involved chordae tendinae. Patients were excluded from the study if they had significant aortic valve disease, coronary artery disease, and active rheumatic fever. All patients with isolated mitral regurgitation underwent reconstructive procedures and have not been included in this study. Patient Characteristics Institutional review board approval for this study protocol was available and informed consent was obtained from all patients. Four hundred and fifty-one consecutive patients undergoing MVR for rheumatic heart disease from January 1996 through December 1999 at All India Institute of Medical Sciences, New Delhi, India, were included in this prospective study (Fig 1). Their demographic and clinical profiles are depicted in Table 1. Dyspnea on exertion was the predominant symptom, and 447 patients (99.1%) were in New York Heart Association (NYHA) functional class III or IV. Congestive cardiac failure was present in 167 (37.0%) patients. Two per cent (9 of 451) of patients had associated atrial septal defect, and 7.5% (34 of 451) had left atrial thrombus. Atrial fibrillation was present in 307 (68%) patients. Fifty-five patients (12.1%) had prior closed mitral valvotomy, 62 patients (13.7%) had previous balloon mitral valvuloplasty, and 25 patients (5.5%) had undergone prior mitral valve repair. During this period, 315 patients with mitral regurgitation underwent mitral valve reconstruction by the techniques described by us earlier [6]. The technique for preservation of the chordopapillary Table 1. Demographic Details of the Study Group Profile Nonchordal I Postchordal II Total III p Value No. of patients, n (%) (n 451) 70 (15.6) 124 (27.8) 257 (56.9%) Male population, n (%) 282 (62.5%) 42 (60%) 80 (64.5%) 160 (62.2%) 1.000 Age in years (mean SD) 39 15 33 19 35 23 0.896 NYHA class n (%) II 0 0 4 (1.5%) 0.005 III 50 (71.4%) 73 (58.8%) 157 (61.0%) 0.56 IV 20 (28.6%) 51 (41.2%) 96 (37.3%) 0.94 Pathology, n (%) Predominant-MS 26 (37.1%) 53 (42.7%) 84 (32.7%) 0.002 Mixed lesion (MS MR) 44 (62.9%) 71 (57.3%) 173 (67.3%) 0.000 Size of valve, n (%) No. 33 8 (11.4%) 21 (16.9%) 75 (29.1%) 0.001 No. 31 21 (30%) 51 (41.2%) 101 (39.2%) 0.06 No. 29 28 (40%) 42 (33.8%) 44 (17.1%) 0.000 No. 27 7 (10%) 5 (4.0%) 21 (8.1%) 0.005 No. 25 6 (8.6%) 5 (4.0%) 16 (6.2%) 0.78 Atrial fibrillation Preoperative 44 (62.8%) 77 (62.0%) 186 (72.3%) 0.078 Postoperative 28 (40%) 58 (46.7%) 109 (42.4%) 0.61 Postoperative inotrope requirement 68 (97.1%) 94 (75.8%) 58 (22.5%) 0.000 MR mitral regurgitation; MS mitral stenosis; NYHA New York Heart Association; SD standard deviation.

1928 CHOWDHURY ET AL Ann Thorac Surg MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 2005;79:1926 33 Fig 2. Diagrammatic representation of the various steps of total chordal preservation. (A) Incision along the anterior mitral ring from the anterior to posterior commissure. (B) The anterior mitral leaflet is divided in the center (broken line) to inspect the subvalvular apparatus. The central segment, which is devoid of chordal insertion, is resected. (C) The separated anterior and posterior segments are resuspended to the annulus at the respective commissures. (D) The middle scallop of the posterior leaflet is divided towards the annulus. The posterior mitral leaflet in between scallops is divided at two or three points, when necessary. Stitches for reaffixation are tied. apparatus was made after intraoperative visual assessment of the mitral valve. The patients were allocated to three groups: group I (n 70), MVR with complete excision of the native valve including the subvalvular apparatus (nonchordal group); group II (n 124), MVR with excision of the anterior mitral leaflet and its attached chordae tendinae. The posterior mitral leaflet with chordopapillary apparatus was preserved (posterior chordal group); group III (n 257), MVR with complete preservation of chordae tendinae and papillary muscles of the anterior and posterior leaflet (total chordal group). There was no statistically significant difference in the patient population among the three groups (Table 1). The severity of symptoms and type and number of medications given preoperatively were comparable. Valve Pathology Two hundred and eighty-eight patients (63.8%) had combined mitral stenosis and regurgitation, and 163 (36.1%) had predominant mitral stenosis. All patients of the nonchordal and posterior chordal group had either a mixed type of lesion or predominant mitral stenosis. Total chordal preservation was possible in 60% of patients with mixed mitral valve disease and in 51.5% of patients with mitral stenosis. Overall, 43.0% (194 of 451 patients) had mitral valvular calcification. Surgical Techniques A median sternotomy (n 416) or a right anterolateral thoracotomy (n 35) was used. Moderately hypothermic (28 32 C) cardiopulmonary bypass was established by ascending aortic and bicaval cannulation. Antegrade cold blood cardioplegia and topical hypothermia were used for myocardial preservation. The mitral valve was approached through a left atrial incision behind the interatrial groove in 442 patients. Transseptal approach was employed in patients with associated atrial septal defect (n 9). Prosthetic valves were inserted using 2 0 Ethibond sutures (Ethicon, Cincinatti, OH) over polytetrafluoroethylene pledgets. The St Jude (St Jude Medical, Inc, St Paul, MN) mechanical prostheses (SJM 33 mm, 104 patients; 31 mm, 173; 29 mm, 114; 27 mm, 33; 25 mm, 27) (Table 1) was used in all patients. Disc movement was checked for interference by the preserved chordae tendinae. Fifteen patients (3.3%) underwent concomitant tricuspid annuloplasty. The mean aortic cross-clamp time was 36.0 11.2 minutes (range, 24 to 70 minutes), and the cardiopulmonary bypass time was 44.6 12.8 minutes (range, 38 to 88 minutes). Techniques of Chordal Preservation TOTAL CHORDAL PRESERVATION. The valve was analyzed intraoperatively in a systematic manner to allow the optimal techniques to be chosen (Fig 2A D). The subvalvular apparatus was preserved using the technique described by Miki and colleagues [7]. After incising the anterior mitral leaflet in the center from edge to base, it was separated 3 to 4 mm from the annulus and a central ellipse-shaped portion was excised, leaving a5to10mm rim of leaflet free edge attached to the primary first order or marginal chordae tendinae. The anterior and posterior mitral commissures were incised and the papillary muscles were split. Excessive cuspal tissue was sliced to make it thin. The fibrous and calcific nodules were excised. The anterior Fig 3. Actuarial survival curve (Kaplan-Meier) of three groups of patients undergoing mitral valve replacement.

Ann Thorac Surg CHOWDHURY ET AL 2005;79:1926 33 MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 1929 paramedial chorda, or anterior and posterior paramedial chordae tendinae, or paracommissural chordae tendinae were excised along with splitting and partial shaving of the papillary muscle tip on an individualized basis. The separated anterior and posterior segments of the anterior mitral leaflet were shifted and reattached to the mitral ring near the anterior and posterior commissures, respectively. The midportion of the posterior mitral leaflet was incised in the center from free edge to base. In order to accommodate a large size prosthesis, when necessary, the posterior mitral leaflet was incised from edge to base at two or three additional points between the scallops of the posterior mitral leaflet supported by cleft chordae. The papillary muscles were split down to their base. While securing the prosthetic valve on the annulus, the posterior valve sutures were tied first. Excessive tissue within these chordal buttons that cannot be safely excised was pulled out of the subvalvar area using a nerve hook. The chordopapillary buttons were held on the atrial side (outside the sewing ring) when the valve was seated and the sutures were tied, thus preventing outflow tract obstruction or mechanical obstruction. If the posterior leaflet was excessively redundant or the chordae tendinae were elongated, the leaflet was imbricated into the mitral annulus using pledgeted sutures. POSTERIOR CHORDAL PRESERVATION. In this technique, the anterior mitral leaflet with its attached chordae tendinae was completely excised. The posterior leaflet with the chordopapillary support mechanism was retained. The posterior mitral leaflet was incised at two or three points in between scallops from edge to base, when necessary. Annulus Decalcification and Reconstruction In most instances, the calcification process involved the commissures and was limited to the annulus with variable extension to the posterior myocardial wall, basal and intermediary chords, and head of one or several papillary muscles. Calcification was dealt with by excision of the calcified segment, shaving off the calcified leaflet margin, squeezing or milking out the calcific debris from the mitral annulus, and partial excision of the posterior mitral leaflet with the involved chordae tendinae. Decalcification was done by using a knife to incise the atrial endothelium at the margin of the calcified bar. Then the base of the mural leaflet was incised at the edge of the calcium bloc and retracted. Keeping the edge of the dissecting knife against the calcium, the fibrous capsule overlying the calcium was incised. A thick hemostat and a peanut swab were used to milk out the calcific debris from within the capsule. No patient required en-bloc resection of the calcium deposit or sliding atrioplasty of the left atrium. Nonchordal Group The mitral valve was completely excised, including the leaflets and the subvalvular apparatus in cases of severe subvalvular fusion or calcified mitral leaflets with annular extension. One or two chordal buttons-pillars of the posterior mitral leaflet were retained in some cases. Extensive scarring, shortening, and thickening of the chordopapillary apparatus precluded the use of artificial Gore-Tex sutures (WL Gore and Associates, Flagstaff, AZ) to resuspend the remnant papillary muscle base to the mitral annulus. The technique of valve insertion was the same in all groups. An everting mattress suture (ie, pledgets on the atrial side) was used in all cases. The left atrial appendage was routinely ligated. No surgical procedure was performed for atrial fibrillation. Postoperative Studies These included six-month clinical examinations, electrocardiograms, chest radiographs, cinefluoroscopy, and echocardiography. The functional class at follow-up was noted. Results were reported according to prescribed criteria [8]. All patients received warfarin and aspirin (100 mg/d) for anticoagulation to maintain an international normalized ratio (INR) between 3.0 and 3.5. A minimum of 48 months follow-up was mandatory for this study. Echocardiographic Studies and Measurements Transthoracic two-dimensional (2D), color flow and Doppler echocardiography was performed using a Hewlett-Packard-Sonos-5500 with 2.7 or 3.5 MHz transducer. Prosthetic valve function was assessed on 2D apical four-chamber view, and M-mode parasternal long-axis view. Left ventricular outflow tract obstruction was assessed on an apical five-chamber view, and by Doppler study. A Doppler velocity of greater than 2 m/s was considered significant for LVOTO. Preoperative studies were performed within 7 days before surgery. Postoperatively, all survivors were followed echocardiographically at the time of discharge from hospital, at 1 year, and at 4 year follow-up. All late echoes have been grouped into one time period (48 months) with a range no greater than 6 months. Echocardiographic data were measured according to American Society of Echocardiography criteria [9]. Statistical Analysis Data were analyzed with Biomedical Data Processing Statistical Software (University of California Press, Berkeley, CA) and SPSS 7.0 statistical package (SPSS Inc, Chicago, IL). Descriptive statistics were calculated for continuous and categorical variables. Student s t test was used to identify significant differences between two groups of continuous variables. Repeated measures twoway analysis of variance (ANOVA) with the Bonfferoni posthoc test was used to assess the influence of time (preoperatively vs postoperatively vs 4 years) for type of operative procedure on all echocardiographically derived variables. Percentage change between the preoperative and postoperative values were calculated and compared by oneway ANOVA with posthoc (LSD) analysis for the three groups. The 2 test was used to identify association among the groups for categorical variables. A p value less than 0.05 was considered significant. Mortality rates were calculated depending on the total number of years of follow-up for each patient. Actuarial

1930 CHOWDHURY ET AL Ann Thorac Surg MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 2005;79:1926 33 Table 2. Test of Between-Subject Effects by Two-Way Analysis of Variance (n 426) End-Systolic Volume End-Diastolic Volume Group Preoperative At Discharge At 4 Years p Value Preoperative At Discharge At 4 Years p Value I(n 59) 52.92 16.75 53.58 20.53 48.18 23.11 0.944 90.46 23.19 84.54 25.64 84.64 26.72 0.001 II (n 117) 50.88 23.40 48.44 20.68 45.94 14.12 0.006 94.44 54.15 83.24 40.92 76.17 15.61 0.000 III (n 250) 49.85 15.06 42.82 14.23 37.00 9.57 0.000 86.82 20.57 76.48 18.52 57.84 11.46 0.000 Between group p value 0.041 0.000 estimates were calculated using the Kaplan-Meier technique and the log-rank test was performed to analyze statistically the difference of survival among the three groups [10]. Valve-related events were reported as per the standard published criteria [8]. Results Early Results There were 11 early deaths (2.4%) due to low-output syndrome (group I: n 5; group II: n 2), malignant ventricular arrhythmias (group III: n 2), and cerebrovascular accidents (group III: n 2). Nine patients were in NYHA functional class IV preoperatively. All patients were administered oral angiotensin converting enzyme (ACE) inhibitors after extubation (0.5 to 1.0 mg/kg; every 8 hours) before weaning from inotropic agents. Digoxin, diuretics, and ACE inhibitors were weaned at varying time intervals. Amiodarone was used for intractable atrial fibrillation. Late Outcomes There were 14 late deaths (3.1%: group I, n 6; group II, n 5; group III, n 3) due to ventricular arrhythmias (n 2), anticoagulant hemorrhage (n 2), congestive heart failure (n 2), and viral hepatitis (n 1). Five patients had valve thrombosis. Two of these developed major cerebrovascular accidents after streptokinase administration and subsequently died. Three patients had successful thrombolysis. Thromboembolic Complications Fifteen patients had thromboembolic complications. Three of them died, 6 recovered with residual weakness, and 4 recovered completely. In 2 patients, the deficit was transient. No single factor was found to be associated with incidence of thromboembolism. Prosthetic Valve Endocarditis Five patients developed prosthetic valve endocarditis. They were treated conservatively and two of these died. Four hundred and twenty-six survivors (94.46%) achieved the mandatory 48-month postoperative followup. Their preoperative and postoperative records were reviewed. Follow-up was 100% complete (range, 1 to 96 months) and yielded 3327.06 patient-years of data with a mean follow-up time of 93.72 months (standard error [SE 0.86]; 95% confidence interval [CI] 92.02 to 95.41 months). The actuarial survival at 96 months was 84.29 0.04% in group I, 94.17 0.02% in group II, and 96.01 0.01% in group III (Fig 3). By log-rank test, the difference of survival was statistically significant among the three groups (p 0.0002). All survivors of group II and III (n 361) were in NYHA functional class I or II at their last follow-up. A 92.3% (60 of 65) of survivors of group I are in NYHA functional class I and II. A 63.5% (195 of 307) of patients who had preoperative atrial fibrillation continue to remain in atrial fibrillation. Chordopapillary preservation techniques did not affect the outcome of postoperative atrial fibrillation (p 0.61). There were no structural deteriorations or reoperations. Preoperative and Postoperative Echocardiographic Data Tables 2 and 3 provide the between group and the within group comparative data of echocardiographically (preoperative, at discharge from hospital, and at 48 months) measured variables among different groups of patients. To further evaluate the changes in variables between groups, the differences were expressed as fractional change; ie, percentage change between the preoperative and postoperative values. Two way repeated-measures analysis of variance revealed. 1. Left ventricular end-systolic volume (LVESV) decreased slightly from the preoperative level in group I in the immediate postoperative period. Although there was gradual improvement at 1 to 4 years of follow-up, the improvement was not statistically significant (p 0.944). The remaining groups (II and III) demonstrated statistically significant reduction of LVESV (p 0.05) in the immediate as well as late postoperative period. The total chordal group (group III) demonstrated greater fractional change of LVESV as compared to the posterior chordal and nonchordal group. 2. Left ventricular end-diastolic volume (LVEDV) decreased by comparable degrees in all three groups in the immediate postoperative period and on follow-up (p 0.000). Only group III had statistically significant percentage reduction of LVEDV at 4 years of follow-up. 3. Preoperatively, there were no significant differences in left ventricular ejection fraction and fractional shortening among the groups. Both variables

Ann Thorac Surg CHOWDHURY ET AL 2005;79:1926 33 MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 1931 Table 2. Continued Ejection Fraction Fractional Shortening Group Preoperative At Discharge At 4 Years p Value Preoperative At Discharge At 4 Years p Value I(n 59) 53.30 6.67 45.17 8.16 44.63 8.58 0.051 31.29 6.94 27.20 8.39 20.08 8.03 0.001 II (n 117) 52.40 8.10 44.33 8.41 51.88 8.72 0.289 29.84 5.80 20.43 39.73 27.08 7.59 0.480 III (n 250) 86.82 20.57 76.48 18.52 57.84 11.46 0.066 30.97 9.37 30.18 8.72 30.15 11.41 0.878 Between group p value 0.031 0.048 Echo data: mean standard deviation. continued to decline over time in the nonchordal group (group I; p 0.05 and p 0.001, respectively) and returned to preoperative levels after the initial decline in the chordal preservation groups. At the end of 4 years, the fractional change of ejection fraction was statistically significant only in the chordal preservation groups (II and III). Comment Bileaflet Versus Posterior Chordal Preservation: Possibilities and Limitations The importance of bileaflet preservation in patients undergoing mitral valve replacement remains controversial [1 4, 11]. Many surgeons continue to retain only the posterior leaflet with chordae tendinae because of concerns over greater technical complexity, longer operating time, potential interference with mechanical leaflet motion, need to undersize the mitral prosthesis, and the possibility of creating left ventricular outflow tract obstruction [1 5, 11]. To overcome the limitations of bileaflet preservation, a variety of techniques have been introduced [7, 12 14]. These differ primarily in the location where the anterior leaflet chordae are inserted in the mitral annulus. The tension of the preserved main anterior leaflet chordae may act on the posterior annulus (Feike s technique), the trigonal area (Miki s technique), on the anterior annulus (Khonsari s I and II technique), or on a point half-way between these locations (Hetzer s technique) [7, 12 14]. Magnetic resonance studies of annulus motion have indicated interesting phenomena characteristic of the respective techniques, such as parallel prosthetic movement with Khonsari s technique and tilting of the prosthesis in Feike s technique [14]. There are differences in the tension on chordae during the cardiac cycle in various techniques but there is no established method for predefining chordal length at the time of prosthetic implantation, nor for determining the required length according to the various types of mitral disease, left ventricular dimensions, or location of chordal reattachment. The use of artificial Gore-Tex chordae during MVR has been popularized by some; we have not used the same [15, 16]. There is a possibility of thickening and hardening of the preserved chordae tendinae because of restricted physiologic movement by the prosthetic valve [13, 14]. We believe that a divided, shifted, and reaffixed anterior leaflet with chordae tendinae may not interfere with the left ventricular outflow tract (LVOT) [16]. No chordal structure obstructed the LVOT with this technique. Doppler echocardiographic examination did not show any evidence of LVOTO in any patient with preserved anterior mitral leaflet. Technically, total chordal preservation was feasible in 60% of our patients with mixed mitral valve disease and in 51.5% of patients with predominant mitral stenosis. An argument against preservation of the anterior leaflet was that only undersized valve prosthesis could be implanted [1 4]. However, we have implanted a 29 to 33 mm prosthesis in 85.6% of patients with total chordal preservation, suggesting that preservation of the anterior mitral leaflet does not preclude implantation of a large prosthesis. Complete Versus Partial Chordal-Sparing MVR: Effects on Left Ventricular Volume and Function Preserving the subvalvular mitral apparatus has been recognized as necessary for improvement of left ventricular systolic function, exercise capacity, and better survival after MVR [1 4, 11, 16, 17]. It has been shown to preserve regional left ventricular mechanics and threedimensional contraction synergy, and may prevent myocardial rupture [1 4, 11, 16, 17]. Reports addressing the issue of left ventricular mechanics with bileaflet or posterior leaflet MVR are limited [2 4, 11, 17]. Although Hannein and colleagues [3] and Rozich and colleagues [17] demonstrated the superiority of chordal-sparing MVR over conventional MVR, no significant differences were noted between patients receiving either posterior or bileaflet chordal preservation. Our study demonstrates that MVR with bileaflet or posterior chordal preservation is associated with a lesser incidence of postoperative low output syndrome (p 0.000) and better long-term survival than conventional MVR (p 0.0002; Fig 3). Also, patients undergoing bileaflet-preserving MVR derived greater functional benefit than patients undergoing MVR without chordal preservation. Echocardiographically, the total chordal-preservation group demonstrated statistically significant improvement of left ventricular diastolic and systolic dimensions over posterior and nonchordal groups (Tables 2 and 3). Similar results were reported by others [2 4, 11, 16, 17]. This supports the observation that chordopapillary pres-

1932 CHOWDHURY ET AL Ann Thorac Surg MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 2005;79:1926 33 Table 3. Pairwise Comparisons by Posthoc Analysis (n 426) End-Systolic Volume End-Diastolic Volume Ejection Fraction Fractional Shortening At Discharge At 4 Years At Discharge At 4 Years Preoperative At Discharge At 4 Years Preoperative At Discharge At 4 Years Preoperative Preoperative I v/s II (p-value) NS NS NS NS NS 0.04 NS NS 0.02 NS NS 0.001 II v/s III (p value) NS 0.04 0.000 NS NS 0.005 NS 0.001 0.01 NS 0.00 0.05 I v/s III (p value) NS 0.04 0.001 NS 0.01 0.008 NS 0.05 0.00 NS 0.05 0.004 NS not significant. ervation is an important determinant of postoperative left ventricular function, and the increased afterload produced by a competent valve is of less consequence. Limitations of This Study This study was not randomized. Given the mounting evidence favoring conservative mitral valve surgery, a prospective, randomized controlled trial may no longer be considered ethical. Our methods of measuring left ventricular function may be criticized for inaccuracy, because these are operator dependent. However, all echo measurements were performed by experienced cardiologists. We have not assessed global and regional systolic stress, which is increased after chordal transection. Conclusions We conclude that total chordal preservation is possible in the majority of patients undergoing MVR for rheumatic heart disease. An appropriate sized prosthesis can be implanted despite bileaflet preservation. This technique provides superior results compared to non and partial chordal preservation. We hope these technical modifications will be useful to surgeons attempting to emulate this approach on an individual basis. We are grateful to Shankar Sharma for preparation of the manuscript. References 1. Lillehei CW. New ideas and their acceptance as it has related to preservation of chordae tendinae and certain other discoveries. J Heart Valve Dis 1995;4(suppl 2):S106 14. 2. Le Tourneau T, Grandmougin D, Foucher C, et al. Anterior chordal transection impairs not only regional left ventricular function but also regional right ventricular function in mitral regurgitation. Circulation 2001;104(suppl 1):141 6. 3. Hannein HA, Swain JA, McIntosh CL, et al. Comparative assessment of chordal preservation versus chordal resection during mitral valve replacement. J Thorac Cardiovasc Surg 1990;99:828 37. 4. Kayacioglu I, Ates M, Sensoz Y, et al. Comparative assessment of chordal preservation versus chordal resection in mitral valve replacement for mitral stenosis (long-term follow-up: 8 years). Tohoku J Exp Med 2003;200:119 28. 5. Thomson LE, Chen X, Greaves SC. Entrapment of mitral chordal apparatus causing early postoperative dysfunction of a St. Jude mitral prosthesis. J Am Soc Echocardiogr 2002;15:843 4. 6. Choudhary SK, Talwar S, Dubey B, Chopra A, Saxena A, Kumar AS. Mitral valve repair in a predominantly rheumatic population long-term results. Tex Heart Inst J 2001;28:8 16. 7. Miki S, Kusuhara K, Ueda Y, et al. Mitral valve replacement with preservation of chordae tendinae and papillary muscles. Ann Thorac Surg 1988;45:28 34. 8. Edmunds LH Jr, Clark RE, Cohn H, Grunkemeier GL, Miller DC, Wiesel RD. Guidelines for reporting morbidity and mortality after cardiac valvular operations. Ann Thorac Surg 1996;62:932 5. 9. Cheitlin MD, Armstrong WF, Aurigemma GP, et al. Guideline update for the clinical application of echocardiography: summary article. J Am Soc Echocardiogr 2003;16:1091 110.

Ann Thorac Surg CHOWDHURY ET AL 2005;79:1926 33 MVR, CHORDAL PRESERVATION, RHEUMATIC MV DISEASE, AND LV FUNCTION 1933 10. Kaplan EL, Meier P. Non-parametric estimation from incomplete observations. J Am Stat Assoc 1958;53:457 81. 11. Yun Kl, Sintek CF, Miller DC, et al. Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: effects on left ventricular volume and function. J Thorac Cardiovasc Surg 2002;123:707 14. 12. Feikes HL, Daugharthy JB, Perry JE, et al. Preservation of all chordae tendinae and papillary muscle during mitral valve replacement with a tilting disc valve. J Cardiac Surg 1990;5: 81 5. 13. Sintek CF, Pfeffer TA, Kochamba GS, Khonsari S. Mitral valve replacement: technique to preserve the subvalvular apparatus. Ann Thorac Surg 1995;59:1027 9. 14. Hetzer R, Drews T, Siniawski H, Komoda T, Hofmeister J, Weng Y. Preservation of papillary muscles and chordae during mitral replacement: possibilities and limitations. J Heart Valve Dis 1995;4(suppl 2):S115 23. 15. Komeda M, DeAnda A Jr, Glasson JR, et al. Improving methods of chordal sparing mitral valve replacement. Part III: Optimal direction for artificial chordae. J Heart Valve Dis 1996;5:484 90. 16. Wasir H, Chaudhary SK, Airan B, et al. Mitral valve replacement with chordal preservation in a rheumatic population. J Heart Valve Dis 2001;10:84 9. 17. Rozich JD, Carabello BA, Usher BW, et al. Mitral valve replacement with and without chordal preservation in patients with chronic regurgitation: mechanism for differences in postoperative ejection performance. Circulation 1992;86:1718 26. Notice From the American Board of Thoracic Surgery The 2005 Part I (written) examination will be held on Monday, December 5, 2005. It is planned that the examination will be given at multiple sites throughout the United States using an electronic format. The closing date for registration is August 1, 2005. Those wishing to be considered for examination must apply online at www.abts.org. To be admissible to the Part II (oral) examination, a candidate must have successfully completed the Part I (written) examination. A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 6333 N St. Clair St, Suite 2320, Chicago, IL 60611; telephone: (312) 202-5900; fax: (312) 202-5960; e-mail: info@abts.org. 2005 by The Society of Thoracic Surgeons Ann Thorac Surg 2005;79:1933 0003-4975/05/$30.00 Published by Elsevier Inc