Double row of overlapping sutures for downsizing annuloplasty decreases the risk of residual regurgitation in ischaemic mitral valve repair

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1 European Journal of Cardio-Thoracic Surgery 49 (2016) doi: /ejcts/ezv291 Advance Access publication 8 September 2015 ORIGINAL ARTICLE Cite this article as: Nappi F, Spadaccio C, Chello M, Lusini M, Acar C. Double row of overlapping sutures for downsizing decreases the risk of residual regurgitation in ischaemic mitral valve repair. Eur J Cardiothorac Surg 2016;49: Double row of overlapping sutures for downsizing decreases the risk of residual regurgitation in ischaemic mitral valve repair Francesco Nappi a,b, Cristiano Spadaccio a, Massimo Chello a, Mario Lusini a and Christophe Acar c, * a Department of Cardiovascular Surgery, University Campus Bio-Medico, Rome, Italy b Department of Cardiac Surgery, Centre Cardiologique du Nord, Saint Denis, France c Department of Cardiothoracic Surgery, Hôpital Pitié-Salpétrière, Paris, France * Corresponding author. Department of Cardiac Surgery, Hôpital de la Salpétrière, Bd Vincent Auriol, Paris, France. Tel: ; fax: ; c.acar@psl.aphp.fr (C. Acar). Received 17 March 2015; received in revised form 14 July 2015; accepted 22 July 2015 Abstract OBJECTIVES: The aim of this study was to evaluate a novel insertion technique of the prosthetic ring that would further magnify the degree of annulus narrowing, thereby reducing the potential for a residual leak in ischaemic mitral valve repair. METHODS: Thirty-six patients with ischaemic mitral regurgitation (MR) were randomly assigned into two groups. In 18 patients, the prosthetic ring was inserted in the conventional manner with a single row of sutures (control group). In the remaining 18 patients, the ring was attached using a double row of sutures tied both on the inner and on the outer part of the sewing cuff. Both groups had similar preoperative clinical and echocardiographic characteristics with severe leaflet tethering: mean tenting area >2.5 cm 2, mean anterior leaflet angle >25 and posterior leaflet angle >45. The mean prosthetic ring sizes inserted in both groups were identical (mean: 27.3 mm). RESULTS: At 12 months, there was no clinical event except for 1 rehospitalization in the control group. The mean mitral regurgitation grade was higher in the control group than in the group with the double row of sutures at 1.6 ± 0.9 vs 0.7 ± 0.3 (P = ). Annulus diameter reduction was less pronounced in the control group when compared with the group with the double row of sutures, both in the parasternal long-axis: 29.3 ± 3 vs 26.3 ± 3 mm (P = ) and in apical four-chamber views: 31 ± 3 vs 28 ± 2 mm (P = 0.003). Leaflet tethering indices were greater in the control group than in the group with the double row of sutures: tenting area: 1.42 ± 0.3 vs 1.1 ± 0.5 cm 2 (P = 0.002), anterior leaflet angle: 33 ± 3 vs 28 ± 5 (P = ) and posterior leaflet angle: 110 ± 13 vs 80 ± 11 (P = ). Left ventricular function parameters were not statistically different among the two groups. CONCLUSION: A double row of overlapping sutures for attaching the prosthetic ring in downsizing is more efficient in narrowing the mitral annulus than the conventional technique in ischaemic mitral repair. Even in high-risk patients whose leaflets were severely tethered on echocardiography, it almost eliminated the risk of MR recurrence in this study. Keywords: Ischaemic mitral valve insufficiency Mitral valve repair Mitral INTRODUCTION Mitral valve repair of ischaemic mitral insufficiency using downsizing is still flawed by a risk of failure in specific subgroups in which leaflet tethering is particularly severe [1 3]. The aim of this study was to describe a novel technique for attaching the prosthetic ring that would further magnify the degree of annulus narrowing, thereby reducing the potential for a residual leak. METHODS Inclusion and exclusion criteria Between 2009 and 2011, 36 patients with severe (grade 3 or 4) ischaemic mitral valve insufficiency were randomly assigned in an 1 : 1 ratio into two groups according to the technique of used for inserting the prosthetic ring (n = 18 in each group). Patients with leaflet prolapse-related papillary muscle rupture or elongation, as well as those presenting with chordal rupture or elongation due to an associated myxomatous disease, were excluded. Only patients whose primary mechanism of valve regurgitation was leaflet tethering combined with annulus dilatation were considered. Patients requiring an additional surgical procedure besides coronary bypass grafting due to a coexisting aortic valve disease or another cardiac disorder were excluded. The local ethical committee approved the protocol, and all individuals provided informed consent to enter the study. The study conforms to the Declaration of Helsinki. The study was not supported by any external source of funding. No valve manufacturer had any role in the study. The Author Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

2 F. Nappi et al. / European Journal of Cardio-Thoracic Surgery 1183 Table 1: Patients characteristics Conventional Double row of sutures P-value Preoperative clinical data Age (years) 57.6 ± ± Male ratio 14 (78%) 15 (83%) 0.24 Family history of coronary disease 4 (22%) 2 (19%) 0.12 Systemic hypertension 4 (22%) 2 (19%) 0.12 Dyslipidaemia 10 (55%) 11 (61%) 0.76 Diabetes 7 (39%) 8 (44%) 0.18 Atrial fibrillation 6 (33%) 7 (39%) 0.23 Angina pectoris 11 (61%) 9 (50%) 0.23 Myocardial infarction 18 (100%) 18 (100%) 0.9 Anteroseptal 1 (5%) 2 (10%) 0.58 Lateral 4 (22%) 5 (28%) 0.48 Inferior 13 (73%) 11 (62%) 0.76 Mean NYHA class 3.4 ± ± Preoperative echocardiography Mitral regurgitation grade 3.64 ± ± Effective regurgitant orifice area (mm 2 ) 39 ± ± Annulus diameter: parasternal long axis (mm) 38 ± 6 37 ± Annulus diameter: four-chamber apical (mm) 41 ± 6 40 ± Tenting area (cm 2 ) 3.1 ± ± Anterior mitral leaflet angle ( ) 33 ± 4 33 ± Posterior mitral leaflet angle ( ) 60 ± ± Left ventricular ejection fraction (%) 42 ± ± Left ventricular end-systolic volume index (ml/m 2 ) 62 ± ± Systolic pulmonary pressure (mmhg) 50 ± ± Intraoperative variables Prosthetic ring intercommissural distance (mm) 27.3 ± ± Mean number of coronary bypass grafts 2.1 ± ± Ischaemic time (min) 68 ± ± Cardiopulmonary bypass time (min) 77 ± ± Data are given as mean ± SD or n (%). Preoperative clinical patient characteristics are presented in Table 1. Preoperative echocardiographic study All patients underwent preoperative transthoracic echocardiographic assessment within 2 weeks before the operation. The grade of mitral valve regurgitation was assessed by the extent of the regurgitant jet and the effective regurgitant orifice area was measured. The diameter of the mitral annulus was measured in mid-systole using both a parasternal long-axis view and a four-chamber apical view. Deformation of the mitral valve secondary to leaflet tethering was quantified in the long-axis parasternal view in mid-systole by measuring, the tenting area, the angle between the anterior leaflet and the plane of the mitral annulus as well as the angle between the posterior leaflet and the plane of the annulus. Left ventricular function was evaluated by measuring the ejection fraction and the end-systolic volume (LVESV) according to the modified biplane Simpson s method. Systolic pulmonary artery pressure was extrapolated from Doppler study of the tricuspid flow. Surgical procedure The mitral valve was approached using the standard interatrial groove incision and exposed using the Carpentier retractor. Leaflet restriction due to excess traction on the leaflets leading to a lack of coaptation was diagnosed in all patients (Fig. 1A). No other technique besides downsizing prosthetic ring was used for repairing the mitral valve in this study. The anterior leaflet area was calibrated using a prosthetic ring obturator, and a Carpentier Physioring (Edwards Lifescience, Irving, CA, USA) two sizes smaller that of the obturator was inserted (Fig. 1A). The prosthetic ring was fixed using 2/0 braided sutures placed 1 mm away from the leaflets hinge on the atrial wall. Sutures were placed circumferentially starting as usual at the level of the posterior commissural area in a counterclockwise fashion. Larger bites were used at the posterior part of the annulus from trigone to trigone in order to accentuate the downsizing effect at this level. All sutures were then passed through the prosthetic ring cuff. The ring was lowered into position and the sutures were tied. Intraoperative variables including prosthetic ring sizes are noted in Table 1. Annuloplasty with single row of sutures (control group) (n = 18). A conventional technique of ring insertion using a single row of sutures as described above was achieved. All sutures were passed through the external part of the prosthetic ring cuff. Annuloplasty with double row of sutures (n = 18). First, one row of sutures was placed circumferentially as usual, starting at the level of the posterior commissural area in a counterclockwise fashion. These were then passed through the ADULT CARDIAC

3 1184 F. Nappi et al. / European Journal of Cardio-Thoracic Surgery Figure 1: Surgical procedure. (A) Ischaemic mitral insufficiency related to leaflet tethering together with annulus dilatation. The anterior leaflet area is measured using an obturator and a ring two sizes smaller is selected. The circumference of the annulus following prosthetic ring is shown by the dotted line so as to emphasize the amount of downsizing. (B) The first row of sutures (blue) is tied circumferentially in the inner part of the prosthetic ring. The second row of stitches with different colours (green) is placed from one commissural area to the other overlapping the first row of sutures and then passed through the outer portion of the ring. inner part of the prosthetic ring. Then, using the same type of suture with different colours (Fig. 1B), a second row of stitches was placed so as to overlap the first row of sutures from one trigone to the other, starting with the posterior commissure in a clockwise fashion. Those were then passed through the outer portion of the prosthetic ring cuff (Fig. 1B). Hence, there were twice as many sutures placed posteriorly from trigone to trigone when compared with the conventional technique. The ring was then lowered into position; at that time, some resistance could occur due to the great number of sutures on a small ring and these should be moistened with saline to avoid excess traction on the atrial tissue. The use of different colours made it easier to recognize the inner and the outer row when tying the sutures. Follow-up There was no perioperative death. One-year follow-up was obtained for all patients and cardiac events were noted. In addition, transthoracic echocardiography was performed in all cases at 12 months. The same parameters using the same method as in the preoperative study were recorded: regurgitation grade, tenting area as well as anterior and posterior leaflet angles. Concerning annulus measurements, the prosthetic ring itself was disregarded, and only the anatomical annulus diameter, i.e. the distance separating the attachment of the leaflets in mid-systole was considered in both parasternal long-axis and four-chamber apical views. Left ventricular function was again evaluated using the same parameters: ejection fraction, LVESV and systolic pulmonary artery pressure. Statistical analysis To estimate the total number of patients required to demonstrate a statistical significant influence of the proposed novel technique on primary and secondary endpoints, an inverse power analysis was performed. For this purpose, data generated by Gelfand et al. [4] were applied in which, to detect a 20% improvement of the variable assuming two-sided 5% significance level at 80% power, 16 patients were needed. This was increased to a recruitment target of 18 patients assuming up to 10% non-compliance with the study protocol. Continuous data are presented as mean ± standard deviation; categorical data are presented as a count (percentage). Continuous variables were compared using unpaired Student s t-test and categorical data with Fisher s exact test. Analysis of binary endpoints was accomplished using contingency table analysis. Significance of results was assessed with the χ 2 test uncorrected for continuity. To control for the errors that resulted from possible deviations of the continuous variables from a normal distribution, this analysis was verified by the Mann Whitney U test, which produced similar results. P-values of <0.05 (two-tailed) were taken to indicate statistical significance. Analysis was performed with the SPSS version 20.0 software for Mac. RESULTS Preoperative data There was no statistical difference between the two groups among preoperative variables (Table 1) including age, risk factors for atheroma, presence of angina pectoris and signs of congestive heart failure (NYHA class). All patients had suffered a preoperative myocardial infarction with no difference among groups concerning the localization of the infarct. Likewise, the two groups had similar echocardiographic characteristics (Table 1): same amount of mitral regurgitation and same degree of left ventricular function impairment. Leaflet tethering was equally severe in both groups, with a mean tenting area exceeding 2.5 cm 2 and a mean anterior and posterior leaflet angle above 25 and above 45, respectively. The annulus was markedly dilated to a same extent with values exceeding 37 mm in the two groups in both long-axis parasternal and apical four-chamber views. Intraoperative data Intraoperative variables were also similar in the two groups (Table 1). Prosthetic ring dimensions sized according to the

4 F. Nappi et al. / European Journal of Cardio-Thoracic Surgery 1185 Table 2: Twelve-month echocardiographic follow-up Conventional Double row of sutures P-value Mitral regurgitation grade 1.6 ± ± Annulus diameter: parasternal long axis (mm) 29 ± 3 26 ± Annulus diameter: four-chamber apical (mm) 31 ± 3 28 ± Tenting area (cm 2 ) 1.42 ± ± Anterior mitral leaflet angle ( ) 33 ± 3 28 ± Posterior mitral leaflet angle ( ) 110 ± ± Left ventricular ejection fraction (%) 41 ± 8 46 ± Left ventricular end-systolic volume index (ml/m 2 ) 56 ± ± Systolic pulmonary artery pressure (mmhg) 47 ± 8 42 ± intercommissural distance (Carpentier Physioring) were identical in both groups: 28 mm (n = 12) and 26 mm (n = 6), mean: 27.3 mm for a mean internal intercommissural diameter: 27.3 mm and a mean anteroposterior diameter: 19.3 mm (equal in both groups). Twelve-month follow-up There was no death and no reoperation during the follow-up period. All patients were clinically improved and were in functional NYHA class I II. The only reported cardiac event was 1 rehospitalization for a transient episode of congestive heart failure with moderate mitral regurgitation in the control group. Twelve-month echocardiographic data are reported in Table 2. The number of patients with recurrence of a mild-to-moderate mitral regurgitation at 12 months was significantly higher in the control group, with a mean regurgitation grade of 1.6 ± 0.9 vs 0.7 ± 0.3 in the group with the double row of sutures (P = ). Annulus diameters were markedly decreased when compared with preoperative values, but remained larger in the control group when compared with the group with the double row of sutures according to both parasternal long-axis and apical four-chamber views (P = and 0.003, respectively). Leaflet tethering indices measurements showed that the tenting area and both the anterior and the posterior leaflet angles were greater in the control group than in the group with the double row of sutures (P = 0.002, and , respectively). Left ventricular ejection fraction values were not statistically different among the two groups and remained unchanged when compared with their preoperative values. At 12 months, the LVESV index was slightly lower in the group with the double row of sutures when compared with the control group (P = 0.04). The 12-month systolic pulmonary artery pressure decreased when compared with its preoperative measurement: from 50 ± 11 to 47 ± 8 mmhg in the control group (P < 0.001) and from 49 ± 11 to 42 ± 10 mmhg in the group with the double row of sutures (P < 0.001) with no difference among those two groups. DISCUSSION Valvular leakage in ischaemic mitral valve insufficiency results from leaflet tethering induced by segmental left ventricular and papillary muscle dysfunction combined with a variable extent of annulus dilatation [5, 6]. Various techniques directly applied to the subvalvular apparatus, such as chordal cutting [7], papillary muscle re-approximation [8, 9] and attempt at correcting leaflet tethering, have been described, but none of them have proved to be capable of restoring normal leaflet motion. Although these can offer useful adjuncts, the fundamental basic technique for repairing ischaemic mitral valve insufficiency has remained prosthetic ring [10, 11]. To treat annulus dilatation and more importantly to counteract leaflet tethering and to force the coaptation of the restricted leaflets, the use of a markedly undersized ring is mandatory. Unfortunately, in spite of downsizing, surgical repair of ischaemic mitral valve insufficiency is still flawed by a significant risk of residual regurgitation that can worsen with time and significantly impair long-term prognosis [1 3]. Recently, different parameters measured by echocardiography have been reported so as to anticipate the failure of downsizing : those include mitral annulus diameter as well as various indices allowing quantifying leaflet tethering [12 14]. The present randomized study was designed so as to improve, if possible, the efficacy of undersizing by reinforcing the attachment of the prosthetic ring using a double row of sutures in comparison with the conventional single-row technique. Baseline clinical and echocardiographic characteristics in the two groups were similar (Table 1). Of note, the patient population in this study had a severe form of ischaemic mitral valve insufficiency and belonged to a cohort of patients in which the risk of mitral insufficiency recurrence has been reported to be high according to the predictive echocardiographic parameters mentioned above: mean annulus diameter >37 mm, tenting area >2.5 cm 2 [12] aswellas anterior and posterior leaflet angles above 25 [13] and 45 [14], respectively (Table 1). In fact, recurrence of a mild-to-moderate insufficiency was occasionally observed at 12 months when using the conventional repair. In contrast, all patients in the group with the double row of sutures had no or trivial mitral regurgitation, and the mean grade of residual regurgitation was significantly lower. Although the sizes of the prosthetic rings were identical in both groups, the diameter of the anatomical mitral annulus measured in between the attachment of the leaflets was significantly smaller in the group with the double row of sutures when compared with the control group. Moreover, the intercommissural internal diameter of the prosthetic rings inserted in this series (27.3 mm) perfectly matched that of the anatomical annulus diameter measured in the apical four-chamber view in the group with the double row of sutures (28 ± 2 mm) as opposed to the control group in which ADULT CARDIAC

5 1186 F. Nappi et al. / European Journal of Cardio-Thoracic Surgery Figure 2: Superiority of double row of sutures annuloplaty: proposed mechanisms. In both cases (A and B), the posterior leaflet appeared to be motionless with a widely open posterior leaflet angle. (A) Conventional undersizing mitral with a single row of sutures tied on the outer part of the sewing cuff. It can be hypothesized that, due to the stress applied on the sutures, localized tearing of the atrial tissue occurred, resulting in places with loose attachment of the ring. Consequently, the ring lay at the base of the leaflets rather than on the atrial wall itself. It accounted for its internal diameter being slightly smaller than that of the anatomical annulus (distance in between the attachment of the leaflets). Accordingly, the tenting area (TA) was larger and the anterior mitral leaflet angle was wider when compared with a double row of sutures (B). (B) Same prosthetic ring size using a double row of sutures tied both in the inner and in the outer part of the sewing cuff. The ring lay firmly attached to the atrial wall and its internal diameter was equal to that of the anatomical annulus. Annulus narrowing was more pronounced than in a conventional, resulting in a large surface of leaflet coaptation. the annulus diameter was larger (31 ± 3 mm). The parasternal long-axis view should theoretically allow an estimate of the anteroposterior diameter (i.e. the smaller diameter) of the mitral valve. When using this incidence in this study, annulus narrowing again appeared more pronounced in the group with the double row of sutures compared with the control group (26 ± 3 vs 31 ± 3 mm, respectively, P = ; Fig. 2). However, there was a discrepancy between these values and that of the actual anteroposterior internal diameter of the prosthetic rings used in this series (mean expected value: 19.3 mm). We believe that this bias was probably related to the fact that echocardiographic measurements were made in an oblique rather than in a strictly anteroposterior crosssection of the mitral orifice. The use of a ring whose area is two sizes smaller than that of the anterior leaflet calibrated with an obturator has been recommended in ischaemic mitral valve repair [9, 10], and this rule was applied in all patients in the present study. Whereas ring for degenerative mitral valve insufficiency usually restores the dimensions of the mitral annulus within its physiological range [15], the need for a pronounced undersized ring in ischaemic repair narrows the dimensions of the annulus far below those of a normal adult mitral orifice [15]. Hence, the traction forces exerted on the sutures attaching the ring are much greater. The ring being smaller, the number of theses sutures is less which further aggravates the physical stress exerted on each individual stitch. This is particularly true in the posterior part of the annulus in which larger bites have been placed as recommended in since this is the area where most of annulus distension takes place. It can be hypothesized that, in the control group, due to the shear stress exerted on the atrial tissue that is occasionally friable, localized tearing occurred when lowering the ring into position or when tying the suture knots and was responsible for multiple microdehiscences, resulting in a partly loose attachment of the ring. In addition, with the sutures being passed in the external part of the sewing cuff, the body of the prosthetic ring lay at the base of the leaflets rather than on the atrial wall itself (Fig. 2A). Conversely, distributing the tension on a double row of sutures allowed releasing the stress on individual stitches and tightly anchored the ring. Owing to the sutures being passed through the inner part of the sewing cuff, the ring lay firmly against the atrial wall slightly away from the leaflet hinge (Fig. 2B). Thus, the lesser degree of residual mitral regurgitation at midterm (12 months) obtained by using a double row of sutures seems to be related to a more efficient annulus reduction. Analysis of the echocardiographic indices of leaflet tethering further corroborated this finding (Table 2). As frequently observed following mitral valve repair, the posterior leaflet was motionless and the posterior leaflet angle was widely open in all patients (Table 2 and Fig. 2). However, in the control group, the anterior leaflet angle did not change when compared with its preoperative value, whereas it significantly decreased in the double row of sutures group. Consequently, the tenting area was larger in the control group, which could account for the higher grade of residual insufficiency in the latter (Fig. 2). In conclusion, the double row of sutures technique described in this study allowed one to precisely decrease the diameter of the anatomical mitral annulus to the internal diameter of the prosthetic ring. Besides ischaemic mitral valve repair, the method could be applied in all situations requiring downsizing such as mitral regurgitation resulting from idiopathic dilated cardiomyopathy. Conflict of interest: none declared. REFERENCES [1] McGee EC Jr, Gillinov AM, Blackstone EH, Rajeswaran J, Cohen G, Najam F et al. Recurrent mitral regurgitation after for functional ischemic mitral regurgitation. J Thorac Cardiovasc Surg 2004;128: [2] Hung J, Papakostas L, Tahta SA, Hardy BG, Bollen BA, Duran CM et al. Mechanism of recurrent ischemic mitral regurgitation after : continued LV remodeling as a moving target. Circulation 2004;110(Suppl 1):II [3] Zhu F, Otsuji Y, Yotsumoto G, Yuasa T, Uneno T, Yu B et al. 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