Tricuspid Annuloplasty Using the MC 3 Ring for Functional Tricuspid Regurgitation

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1 Circulation Journal Official Journal of the Japanese Circulation Society ORIGINAL ARTICLE Cardiovascular Surgery Tricuspid Annuloplasty Using the MC 3 Ring for Functional Tricuspid Regurgitation Dong Seop Jeong, MD, PhD; Kyung-Hwan Kim, MD, PhD* Background: A recently introduced tricuspid annuloplasty ring, the MC 3 ring, has a 3-dimensional form that is designed to remodel the tricuspid valve annulus. The aim of this study was to investigate its clinical performance. Methods and Results: From December 2004 to April 2008, 103 patients underwent tricuspid annuloplasty using the MC 3 ring (mean age, 52±13 years; 63.6% women). The average preoperative tricuspid regurgitation (TR) grade was 2.5±0.8, and the mean preoperative systolic pulmonary artery pressure was 48.4±15.0 (24 88) mmhg; the mean follow-up was 26.7±11.2 (0 52) months. One patient died after surgery (1.0%), because of cor pulmonale. No MC 3 ring-related complications, such as, atrioventricular block, ring dehiscence or thromboembolism, were encountered. Predischarge echocardiography showed a significant decrease in the TR grade (2.5±0.8 to 0.8±0.8, respectively; P<0.001). After a median 15 months, the mean TR grade was stable (0.9±0.8). The mean systolic pulmonary artery pressure was also lower than its preoperative value (33.9±7.9 vs 48.4±15.0 mmhg, respectively; P<0.001). Conclusions: The MC 3 ring provides good mid-term clinical and echocardiographic results for TR. However, long-term follow-up is mandatory to confirm the stability of this procedure. (Circ J 2010; 74: ) Key Words: Regurgitation; Valves; Valvuloplasty Functional tricuspid regurgitation (TR) is increasingly being recognized as a significant cause of morbidity and mortality in cardiac disease, and when severe can considerably reduce long-term survival. 1 3 Echocardiographic studies have suggested that significant changes in tricuspid valve geometry occur during functional TR, such as annular dilatation and tethering of leaflets. 4 6 Moreover, after the tricuspid valve annulus has become dilated, TR inevitably progresses to clinical relevance, 7 and uncorrected moderate or severe TR may persist or deteriorate after left-sided cardiac surgery, potentially leading to progressive heart failure and death. 8,9 Furthermore, reoperation for residual TR is known to be a high-risk procedure, and most studies on the subject have reported a poor prognosis. 10 For this reason, tricuspid valve repair is now recommended for the treatment of functional TR at the time of cardiac surgery, rather than a conservative approach, in the hope that spontaneous regression will occur after correcting the original cardiac disease. 11 However, surgical treatment of functional TR is challenging because of several unsolved questions, such as accurate diagnosis, surgical indications, the optimal surgical procedure, and late results after surgical treatment. In terms of surgical procedures, several basic types of tricuspid annuloplasty have been described, and of these, the De Vega type suture annuloplasty and the ring annuloplasty are representative. However, advice in the literature concerning the merits of these techniques is contradictory Nevertheless, recent clinical studies suggest that moderate to severe TR remains in 10% of patients after tricuspid valve repair using current techniques. 14 In 2004 the Edwards MC 3 annuloplasty ring (Edwards LifeScience, Irvine, CA, USA) for tricuspid annuloplasty was introduced to improve the clinical results of tricuspid annuloplasty for functional TR in this situation. The MC 3 has a saddle-shaped configuration, similar to the tricuspid valve annulus The aim of this study was to evaluate the clinical and echocardiographic results after tricuspid annuloplasty using the MC 3 ring. Methods From December 2004 to April 2008, 103 consecutive patients underwent tricuspid valve annuloplasty for functional TR using the Edwards MC 3 annuloplasty system at Seoul National University Hospital by a single surgeon (K-H Kim). All patients underwent transthoracic echocardiography and cardiac catheterization, except patients with an atrial septal defect. The severity of TR was graded from 1+ to 4+ (1+ mild, 2+ moderate, 3+ moderate to severe, 4+ severe). 17 Received April 6, 2009; revised manuscript received August 22, 2009; accepted September 6, 2009; released online December 15, 2009 Time for primary review: 32 days Department of Thoracic and Cardiovascular Surgery, Seoul National University Boramae Medical Center, *Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Jongno-gu, Seoul, Korea Mailing address: Kyung-Hwan Kim, MD, PhD, Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, 28 Yeongeon-dong, Jongno-gu, Seoul , Korea. kkh726@snu.ac.kr ISSN doi: /circj.CJ All rights are reserved to the Japanese Circulation Society. For permissions, please cj@j-circ.or.jp

2 Tricuspid Annuloplasty Using MC 3 Ring 279 Table 1. Patient Demographics Age (years) 52±13 M/F 37/66 NYHA function class II 50 (49) III 29 (28) IV 6 (6) Preoperative TR grade Mild 52 (50) Moderate 31 (30) Severe 13 (13) Af 60 (58.3) Mean LVEF (%) 56.0±7.5 spap (echo, mmhg) 48.4±15.0 spap (cardiac cath, mmhg) 45.1±13.8 mpap (cardiac cath, mmhg) 29.8±9.8 Preoperative CTR 0.61±0.07 Previous cardiac surgery 4 (4) NYHA, New York Heart Association; TR, tricuspid regurgitation; Af, atrial fibrillation; LVEF, left ventricular ejection fraction; spap, systolic pulmonary artery pressure; echo, echocardiography; mpap, mean pulmonary artery pressure; cardic cath, cardiac catheterization; CTR, cardiothoracic ratio. The indications for tricuspid annuloplasty were (1) TR of grade 1+ or more with annular dilatation, and (2) pulmonary hypertension (systolic pulmonary artery pressure >50 mmhg) with annular dilatation irrespective of the TR grade. Clinical data were analyzed retrospectively and all patients were followed up. The preoperative characteristics of the 103 patients are summarized in Table 1; 34.0% (35/103) were in New York Heart Association (NYHA) functional class III or IV preoperatively, and 59.2% (61/103) had atrial fibrillation (Af); 18.4% (19/103) had left ventricular dysfunction (left ventricular ejection fraction <35%) and 58 (56.3%) had pulmonary hypertension (mean pulmonary artery pressure >25 mmhg); 81.6% (84/103) had grade II or III TR and 58.3% (60/103) had significant cardiomegaly (cardiothoracic ratio >0.6). Five patients had undergone previous cardiac surgery: 4 mitral valve replacements and 1 mitral valvuloplasty. The majority of patients (77.7%, 80/103) had a diagnosis of mitral valve disease with functional TR. The causes of mitral valve disease were rheumatic (70%, 56/80), degenerative (14.4%, 15/80), endocarditic (3.8%, 4/80), and prosthetic valve failure (4.8%, 5/80). Concomitant aortic valve disease with mitral valve disease was present in 30 patients and the etiology was predominantly rheumatic. Atrial septal defect was the cause of functional TR in 23 patients. Preoperative diagnoses are summarized in Table 2. All patients were followed by echocardiography (mean duration, 14.2±9.7 months). All 103 patients completed the follow-up (mean follow-up 26.7±11.2 (0 52) months) and their data were obtained from outpatient medical records. The study protocol was reviewed by the Institutional Review Board of Seoul National University Hospital and approved as a minimal risk retrospective study (Approval Number H ), and as such did not require patient consent. Operative Procedures Intraoperative anesthetic management was performed using Table 2. Etiology of Functional TR Mitral valve disease 80 (77.7) Rheumatic 56 Degenerative 15 Prosthetic valve failure 5 Infective endocarditis 4 Combined with aortic valve disease 30 Rheumatic aortic valve 19 Degenerative aortic valve 3 Bicuspid aortic valve 7 VSD (subaortic type) 1 Congenital heart disease 22 (21.4) ASD 22 Pulmonary embolism 1 (1) Total 103 ASD, atrial septal defect; VSD, ventricular septal defect. Other abbreviation see in Table 1. the same technique in all patients. All operations were performed via median sternotomy. The superior and inferior venae cavae and ascending aorta were cannulated separately for cardiopulmonary bypass. Heparin (3 mg/kg body weight) was administered to maintain an activated clotting time >400 s during cardiopulmonary bypass. In addition to moderate systemic hypothermia, cold crystalloid cardioplegic solution was administered continuously via the aortic root or the coronary sinus. Oxygenation was performed using a membrane oxygenator. Left-sided valve disease or congenital anomalies were corrected first. In patients with Af, a modified Cox maze IV procedure was performed using a cryoablator and bipolar radiofrequency ablator prior to left-sided valve surgery. Typically, after right atriotomy, the tricuspid annulus was measured. We regarded the annulus as dilated when preoperative echocardiography showed TR because of annular dilatation, and/or the annulus was larger than the maximum sizer of the MC 3 ring, and/or the intercommissural distance was >70 mm. 7 When dilated, we performed ring annuloplasty using the Edwards MC 3 annuloplasty system. The ring size was based on the distance between the anteroseptal and septoposterior commissures or on the surface area of the anterior leaflet, then downsized by at least 1 size (Table 3); 30-mm and 32- mm rings were used in more than 60% of the 103 patients. It took less than 20 min to perform tricuspid annuloplasty with this system. Protamine sulfate was administered at a ratio of 1:1 to total heparin to neutralize the effects of heparin following the termination of cardiopulmonary bypass. TR was absent or minimal in all 103 patients after annuloplasty. Mitral valve surgery was performed in 84 patients, aortic valve replacement in 27, the Cox maze IV procedure in 60 and coronary artery bypass in 2 (Table 3). Statistical Analysis Statistical analysis was performed using the SPSS software package (version 11.0, SPSS Inc, Chicago, IL, USA). Intergroup comparisons were performed using the unpaired Student s t-test for continuous variables and the χ2 test (Pearson s χ2 and Fisher s exact tests) for categorical variables. Repeated measures ANOVA was used to compare values at the 3 time points (preoperative, predischarge, and after 3.5 years of follow-up). When differences were found,

3 280 JEONG DS et al. Table 3. Operative Procedures Ring size (mm) (13.6) (34.0) (26.2) (14.6) (11.7) Concomitant procedures Mitral valve repair 17 (16.5) Mitral valve replacement 67 (65.0) Aortic valve repair 1 (1.0) Aortic valve replacement 26 (25.2) Maze procedure 60 (58.3) Surgery for ascending aorta 6 (5.8) Coronary artery bypass graft 2 (1.9) Pulmonary embolectomy 1 (1.0) ASD closure 22 (21.4) Abbreviation see in Table 1. Table 4. Clinical Outcomes Mortality 1 (1.0) Early 1 (1.0) Late 0 Morbidity Low cardiac output 3 (2.9) Atrial fibrillation 17 (16.5) Bleeding 4 (3.9) Neurologic complication 2 (1.9) Pericardial effusion 1 (1.0) Ring-related complications 0 Bonferroni s corrections were applied to find the significance between groups. Linear regression analysis was used to detect correlation between variables of interest, and multivariate analysis was used to identify factors associated with residual TR. Variables from the univariate analysis that were entered into the model were age, sex, rheumatic etiology, mitral valve replacement, postoperative sustained Af, and predis- Figure. Serial changes in the severity of (A) systolic pulmonary artery pressure and (B) tricuspid regurgitation. Table 5. Serial Changes in Echocardiographic Results Preoperative Predischarge Follow-up P value LVESd (mm) 35.0± ± ±5.3** LVEDd (mm) 52.0± ± ± LVEF (%) 56.0± ± ±7.2** LAd (mm) 56.3± ±9.0* 49.7± spap (mmhg) 48.4± ±8.4* 33.9± Preoperative TR > % 1%* 2.9% Residual TR >2+ 1% 2.9% NYHA class 2.2± ± CTR 0.61± ± *P<0.05 between preoperative and predischarge parameters; **P<0.05 between predischarge and follow up parameters. LVESd, left ventricular end-systolic dimension; LVEDd, left ventricular end-diastolic dimension; LAd, left atrial dimension. Other abbreviations see in Table 1.

4 Tricuspid Annuloplasty Using MC 3 Ring 281 charge residual TR. The Kaplan-Meier method was used to determine freedom from residual TR at last follow-up visit. All results are expressed as mean ± standard deviation or as proportions. P<0.05 was considered statistically significant. Results Mortality and Morbidity One patient died on the 8 th postoperative day of cor pulmonale related to coal worker s pneumoconiosis. No late deaths occurred, and overall mortality was 1% (1/103). Postoperative complications included new onset or post-maze Af (n=17), bleeding requiring exploration (n=4), neurologic complications, which resolved completely during follow-up (n=2), and low cardiac output (n=3) (Table 4). There were no ring-related complications such as atrioventricular block, ring dehiscence, endocarditis or thromboembolic events. Table 6. Relationship Between Clinical Parameters and Residual TR After Annuloplasty Uing the MC 3 Ring Parameter r Univariate Multivariate P value P value General Age (years) MC 3 ring size Preoperative period CTR spap (mmhg) mpap (mmhg) Follow-up period CTR LVESd (mm) LVEDd (mm) LVEF (%) LAd (mm) mpap (mmhg) Abbreviations see in Tables 1,5. Serial Changes in Clinical and Echocardiographic Results At their last follow-up visit (mean duration, 17.5±11.3 months), 87 of the 103 patients (84.5%) underwent transthoracic echocardiography. The left ventricular end-systolic dimension reduced and the left ventricular ejection fraction improved during follow-up. The left ventricular end-diastolic dimension was unchanged. The left atrial dimension and systolic pulmonary artery pressure were markedly reduced after surgery compared with their preoperative values, and stable during follow-up (Figure A). NYHA functional class and the cardiothoracic ratio improved during follow-up (Table 5). Preoperative TR grade improved in all patients during the immediate postoperative period (Figure B). Moderate TR was detected in 3 patients during follow-up. One of them had had progressive moderate TR at last follow-up and suffered from ischemic heart disease combined with aggravated dilated cardiomegaly and functional mitral regurgitation. The patient underwent percutaneous coronary intervention and then conservative management of the residual TR. Another developed moderate TR at last follow-up (2 years later), despite trivial TR during the immediate postoperative period, but suffered from postoperative Af. The third patient developed moderate TR combined with dilated cardiomegaly at 5 months postoperatively. He had trivial TR during the immediate postoperative period and normal sinus rhythm until his last follow-up visit. The overall freedom from moderate TR at 4.5 years was 89.9±6.0%. Clinical and Echocardiographic Findings Related to Residual TR Univariate analysis revealed that residual TR (>mild) at last Table 7. Predictors of Residual TR at Last Follow-up Visit Parameter Univariate Multivariate P value P value OR 95%CI General Old age (>65 years) Female Hypertension Reoperation Preoperative Af Pulmonary hypertension LV dysfunction Operative Rheumatic MVD Degenerative MVD Mitral valve replacement Mitral valve repair Aortic valve replacement Follow-up Af Early residual TR LV dysfunction LV, left ventricle; MVD, mitral valve disease; OR, odds ratio; CI, confidence interval. Other abbreviations see in Table 1.

5 282 JEONG DS et al. follow-up visit was significantly related to age, cardiothoracic ratio, left atrial dimension and systolic pulmonary artery pressure at the last follow-up. When the variables that were significant in the univariate analysis were subjected to multiple regression analysis, cardiothoracic ratio and systolic pulmonary artery pressure at last follow-up were found to significantly predict the presence of residual TR (Table 6). Univariate analysis of risk factors showed that preoperative Af (P=0.018), postoperative sustained Af (P=0.002), and residual TR during the immediate postoperative period (P=0.001) were associated with residual TR progression at last follow-up visit. Subsequent multivariate analysis showed that postoperative sustained Af (P=0.032, odds ratio (OR)= 5.657) and residual TR during the immediate postoperative period (P=0.006, OR=7.703) were independent predictors of late TR (Table 7). Discussion This study produced 3 main findings. First, tricuspid annuloplasty using the MC 3 ring for functional TR is effective and its mid-term durability is good. Second, residual TR during follow-up is related to postoperative heart size and systolic pulmonary artery pressure. Third, predischarge residual TR and sustained Af during follow-up are risk factors for residual TR. TR has often been neglected in patients undergoing leftsided cardiac surgery, because it was considered that this secondary type of TR decreases after surgical correction of left-sided lesions. 18,19 However, when left untreated, a significant number of patients develop severe symptomatic TR over time. 6,9 Furthermore, development of significant late functional TR jeopardizes long-term outcomes. 10 Currently, it is well recognized that moderate to severe TR should be corrected at the time of surgical treatment of cardiac diseases such as mitral regurgitation. 4,14,15 However, the surgical indications for the correction of mild to moderate TR remain controversial. Dreyfus et al demonstrated that decisions to perform tricuspid annuloplasty are based on tricuspid annular dilatation rather than on the degree of TR at the time of surgery. 7 Matsunaga et al also reported that preoperative tricuspid annular dilatation is related to the development of late functional TR, especially in patients with ischemic mitral regurgitation. 20 Although several annuloplasty techniques have been developed to correct functional late TR caused by annular dilatation, unfortunately the success of tricuspid annuloplasty is not certain, especially with respect to suture repair techniques, such as the Kay and De Vega methods, which have been widely used. Moreover, residual or recurrent TR after De Vega s suture annuloplasty has been reported as moderate or severe in 16.2% 21 and 33.8% 22 of cases, respectively. The idea of remodeling the annulus using a ring was developed by Carpentier et al. 23 Ring annuloplasty remodels the annulus, decreases tension on suture lines, increases leaflet coaptation, and prevents recurrent annular dilatation. Gatti et al reported good short-term and mid-term results for tricuspid annuloplasty using a Cosgrove-Edwards ring in the tricuspid position. 24 However, Onoda et al measured postoperative TR after Carpentier ring annuloplasty and reported moderate TR in 29% of 31 patients. 25 According to 1 of the largest series on tricuspid valve repair reported by McCarthy et al, the prevalence of 3+ or 4+ residual TR was 14% in 790 patients and the reoperation risk was 4.2% per year at 30 days, fell to 0.08% per year by 3 years, and increased to 2.9% per year by 10 years. 14 As has been shown by other studies, the authors demonstrated the superiority of ring annuloplasty over suture techniques, but found tricuspid annuloplasty by any method did not consistently eliminate functional TR. Some surgeons consider that the use of an annuloplasty ring achieves better results than suture repair. 26 Most of the rings currently being used for tricuspid annuloplasty were originally devised for the mitral valve, and are formed in a single plane. However, the tricuspid annulus has a nonplanar, saddle-shaped, 3-dimensional (D) structure. 27 Experimental 28 and clinical 29 studies have confirmed the complex tricuspid geometry and motion during the cardiac cycle. The 3-D profile of the annuloplasty MC 3 ring is based on the geometry of the normal tricuspid annulus, so for the present study we performed tricuspid annuloplasty using the MC 3 ring in the hope that it would improve results for tricuspid valve repair in cases of functional TR. According to our study results, moderate TR was observed in only 1% of patients during the early postoperative period and in 2.9% at more than 3.5 years after surgery. This result is comparable or perhaps better than those reported previously by Rivera et al 15 and Onoda et al, 25 who reported residual TR in approximately 20% of patients after Carpentier-ring annuloplasty. With regard to ring size selection in tricuspid annuloplasty, there is no golden rule. We chose to use a ring that was 1 size down from the size of the annulus in most patients with functional TR related to left heart disease. In such cases, the annulus was usually less than 34 mm in our series, so 1 size down was enough to eliminate regurgitation. In cases of huge annular dilatation (>36 mm) combined with right atrial enlargement (such as atrial septal defect), we chose a ring that was 2 or more sizes down. In the present study, residual TR was associated with postoperative cardiomegaly and increased systolic pulmonary artery pressure. Cardiomegaly because of right heart failure with pulmonary hypertension might cause leaflet tethering, which is a recognized risk factor for an unfavorable result after tricuspid annuloplasty. 4,19 Our findings indicate that tricuspid annuloplasty alone might not be sufficient to eliminate functional TR in patients with preoperative advanced right heart failure. In addition, we found that early residual TR and Af are risk factors for significant residual TR after annuloplasty, which concurs with the findings of previous investigations of other methods of tricuspid annuloplasty and suggests that patients with persistent right ventricular dysfunction or Af may require additional repair or other types of procedures to correct the abnormalities of the ventricle, despite the use of the new 3-D annuloplasty ring. There are 2 remarkable studies of the short-term results of tricuspid annuloplasty using the MC 3 ring and both reported that the new ring was effective according to both the clinical and echocardiographic results. 30,31 We are among the first to present midterm results of tricuspid annuloplasty performed using the MC 3 ring. The clinical and echocardiographic results were good, and reoperation was not required for residual TR. Furthermore, the TR grade in all cases of residual TR was moderate and the patients were asymptomatic during follow-up. Only one death occurred, and it was related to cor pulmonale. Long-term follow-up results are not yet available, but are required to determine the durability and long-term effectiveness of this 3-D ring annuloplasty technique. Study Limitations First, other disease entities, such as atrial septal defect and

6 Tricuspid Annuloplasty Using MC 3 Ring 283 pulmonary embolism, were included and these can cause right ventricular failure, right heart dilatation, and functional TR because of annular dilatation. We consider that these causes of functional TR were not very different in left-sided cardiac disease. Second, this study was retrospective and descriptive in nature, and it would have been better to have compared the outcomes of the MC 3 ring with other techniques, such as De Vega s suture repair, in a prospective, randomized manner. However, it is difficult to obtain patient consent for such studies. Third, no consensus has been reached concerning the indications for tricuspid annuloplasty. We performed it even in patients with trivial TR if annular dilatation was present at the time of surgery, and this might have caused us to overestimate of the merits of the technique. 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