Ann Thorac Surg 2006;81:42-46
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Coapsys Mitral Annuloplasty for Chronic Functional Ischemic Mitral Regurgitation: 1-Year Results
Yugal K. Mishra, MD, PhD
a
,
*
,
Sanjay Mittal, MD
b
,
Pravesh Jaguri, MD
b
,
Naresh Trehan, MD
a
a Department of Cardiac Surgery, Escorts Heart Institute and Research Centre, New Delhi, India
b Department of Cardiology, Escorts Heart Institute and Research Centre, New Delhi, India
Accepted for publication June 8, 2005.
* Address correspondence to Dr Mishra, Department of Cardiac Surgery, Escorts Heart Institute and Research Centre, Okhla Rd, New Delhi, India (Email: dryugal{at}yahoo.com).
Presented at the Poster Session of the Forty-first Annual Meeting of The Society of Thoracic Surgeons, Tampa, FL, Jan 24–26, 2005.
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Abstract
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BACKGROUND: Untreated functional ischemic mitral regurgitation (MR) leads to reduced survival in patients undergoing coronary artery bypass grafting (CABG). However, mitral repair or replacement increases mortality and morbidity over CABG alone. The Myocor Coapsys annuloplasty system potentially reduces these risks by facilitating MR reduction on a beating heart without atriotomy. We present data from the first 11 patients completing 1-year follow-up of a total of 34 implanted patients.
METHODS: Patients referred for CABG with preoperative grade 2 or greater ischemic functional MR were included in this study. Patients with structural valve defects or who demonstrated MR less than grade 2 after CABG, despite hemodynamic challenge, were intraoperatively excluded. Coapsys consists of two epicardial pads connected by a flexible chord implanted by passing the chord across the left ventricle with special instruments without cardiopulmonary bypass. The system was sized to reduce critical valve dimensions and MR. Serial clinical and echocardiographic data were collected out to 1 year.
RESULTS: Mean age was 58.1 ± 6.6 years and mean ejection fraction, 38.5% ± 7.1%. From baseline to 1-year follow-up, effect on MR grade, MR jet area (cm2), and New York Heart Association class were, respectively, 2.9 ± 0.5 to 1.1 ± 0.8, 7.4 ± 2.9 to 3.0 ± 1.6, and 2.5 ± 0.5 to 1.2 ± 0.4 (all p < 0.05 versus baseline). During follow-up, there were no deaths, device failures, reemergence of grade 3 or 4 MR, heart failure readmission, or valve reoperations.
CONCLUSIONS: The Coapsys annuloplasty system is effective in reducing functional ischemic MR and improving NYHA class. The initial data are encouraging and suggest that the device is safe and benefits are sustained at 1 year.
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Introduction
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Ischemic mitral regurgitation (MR) remains one of the most challenging management problems in cardiac surgery and is associated with suboptimal results. Although most surgeons would agree that severe MR should be corrected at the time of coronary artery bypass grafting (CABG) and that trace to mild MR can probably be left alone, the optimal management of moderate ischemic MR remains controversial [1, 2]. Functional MR results from loss of coaptation of the valve leaflets characterized by dilatation of the mitral valve annulus or papillary muscle displacement with chordal tethering. This valve remodeling results from ventricular enlargement in dysfunctional left ventricles (LV). Mitral regurgitation is commonly considered to be one of the initiators of heart failure, as well as an ongoing impetus of progression of the disease [3, 4]. Annuloplasty is a widely used means of mitral valve repair [5]. However, it does not treat papillary muscle displacement, which may explain why recent reports indicate a high incidence of MR recurrence in annuloplasty-treated patients within 1 year of surgery. Moreover, the nature of the surgical procedure requires cardiopulmonary bypass (CPB), aortic cross-clamping, and atriotomy, all factors that contribute to morbidity and mortality in the dysfunctional LV patient.
The Coapsys device (Myocor, Maple Grove, Minnesota) was designed to treat mitral annular dilatation and the papillary muscle displacement. It has the advantages of being placed on a beating heart without CPB, and the ability to be adjusted under echocardiography guidance.
We have been treating ischemic MR patients using the Coapsys device [6] in a feasibility study. The purpose of the feasibility study is to evaluate the safety and efficacy of the Coapsys device for the treatment of ischemic functional mitral regurgitation through serial follow-up out to 1 year after implantation.
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Material and Methods
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The Coapsys Design
The Coapsys device was developed to treat patients with clinically significant MR and LV dysfunction. The treatment is intended to be at least as effective as currently available treatments for MR reduction, with the following added benefits: (1) the ability to affect and stabilize both the mitral annulus and papillary muscles, (2) off-pump implantation, (3) simple implantation procedure, (4) intraoperatively assessable, (5) reversible implantation, and (6) a repair that does not impede annular dynamics.
The Coapsys device consists of epicardial posterior and anterior pads connected by a flexible, expanded polytetrafluoroethylene–coated, braided polyethylene subvalvular chord (Fig 1). The two pads are located on the epicardial surface of the heart with the load-bearing subvalvular chord passing through the left ventricle. The posterior pad has a superior head and an inferior head configured to create shape change at the mitral annular level and papillary muscle level, respectively. This configuration also allows the device to pass between the papillary muscles and below the valve leaflets, ensuring that the device does not interact negatively with these structures. The device is sized by drawing the anterior and posterior pads together. The polyester covered anterior pad is adjustable and is fixed to the subvalvular chord after sizing the device.
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Fig 1. The Coapsys implant consisting of (A) anterior epicardial pad, (B) posterior epicardial pad with superior head (B(i)) and inferior head (B(ii)), and (C) subvalvular chord.
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Patient Selection
This study was approved by the Institutional Review Board of the Escorts Heart Institute and Research Centre, New Delhi, India. All patients provided informed consent for inclusion in the trial prior to surgery. Patients referred for CABG with preoperative grade 2 or greater ischemic functional MR were included in this study. Cases in which preoperative echocardiography showed structural abnormality of mitral apparatus were excluded from the study. Structural exclusions typically included rheumatic heart disease, leaflet prolapse, chordal rupture, mitral annular calcification, and calcified leaflets. During surgery and after completion of all grafts, patients were evaluated by transesophageal echocardiography for MR status. Patients who demonstrated intraoperative reduction of MR to grade less than 2, despite hemodynamic challenge, were not implanted with Coapsys. Patients with post-CABG regurgitation of grade 2 or more received the Coapsys.
Operative Technique
The entire operation [7] was performed on all patients through a median sternotomy on a beating heart without CPB. Distal coronary anastomoses were performed first with the help of the Octopus system (Medtronic, Minneapolis, Minnesota). After completion of the proximal anastomosis, transesophageal echocardiographic MR evaluation was performed. If MR was grade 2 or greater, the Coapsys device was surgically implanted. The appropriate sites for Coapsys device placement were identified through a combination of external landmarks and two-dimensional epicardial echocardiographic visualization of internal structures, utilizing a custom-designed delivery instrument (Fig 2) with anterior and posterior locators fixed to the heart with vacuum assistance (–400 mm Hg). Device placement avoided papillary muscle interference, the internal mitral apparatus, and main coronary artery branches. The posterior subvalvular chord position was approximately 2.0 cm from the atrioventricular groove and midway between the papillary muscles, with the superior head of the pad directly opposed to the posterior annulus. The anterior position was at the base of the right ventricular outflow tract, approximately 2 cm on the right ventricular side of the left anterior descending coronary artery. After site identification, the Coapsys device was placed using the delivery instrument to guide a thin blunt-tipped needle through the left ventricle from the anterior pad locator to the posterior pad locator. The Coapsys subvalvular chord, with the attached posterior pad, was then threaded through the needle and drawn until the posterior pad rested on the left ventricular wall. The anterior pad was threaded over the chord until it rested on the epicardial surface.
The Coapsys device, with both anterior and posterior pads in position, and with the chord attached to the posterior pad, is initially placed with no tension. Device size, hemodynamics, and echocardiographic measurements were recorded at this time as the presizing data point. The Coapsys device was then sized by drawing the posterior pad toward the anterior pad using a specially designed sizing instrument, which reduces the subvalvular chord length. The MR jet area was assessed on transesophageal echocardiography throughout the process of tightening in the viewing plane showing the maximum MR jet. Final device size was selected when MR was minimized or eliminated. Hemodynamic and echocardiographic measurements were repeated at this after-sizing data point. Subsequently, the anterior pad was fixed to the subvalvular chord and excess chord was trimmed and removed. Long-axis intraoperative transesophageal echocardiograms, which demonstrate final Coapsys device size after the subvalvular chord has been tightened by 20%, are shown in Figure 3.
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Fig 3. Preimplant (left) and postimplant (right) transesophageal echocardiograms, showing the Coapsys subvalvular chord stretched across the left ventricle. The arrow points to the subvalvular chord.
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Follow-Up and Statistical Analysis
Postoperative care was equivalent to that of patients undergoing mitral valve repair or coronary artery bypass grafting procedures. Patients with the Coapsys device were treated with anticoagulation (coumadin) for 3 months postoperatively. All patients were assessed at predischarge, 1 month, 3 months, and then annually with history, physical examination, and transthoracic echocardiography. The 
2 and Fisher exact tests were applied for comparison of categorical data when applicable. Student's t test was applied for comparison of mean values. Unless otherwise stated, aggregate data are presented as mean ± SD.
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Results
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Data for the first 11 patients completing their 12-month follow-up are included. Preoperative characteristics of the 11 patients are shown in Table 1. Most of the patients had advanced coronary artery disease with 73% having documented prior myocardial infarction. The patients without a documented history of myocardial infarction demonstrated baseline electrocardiographic and echocardiographic findings that were consistent with past infarction. This high incidence of prior ventricular damage is consistent with the presence of significant MR, ventricular dysfunction (mean ejection fraction) 38.5% ± 7.1%, and New York Heart Association (NYHA) class II or III status.
Perioperative Results
Perioperative data are shown in Table 2. All patients underwent elective surgery. The mean number of bypass grafts was 2.8 ± 0.9. Left internal mammary artery was used in 64% of cases. None of the 11 patients required perioperative intra-aortic balloon pump for hemodynamic instability. One patient had ventricular tachycardia in postoperative phase and required cardioversion and cardarone infusion.
Clinical and Echocardiographic Follow-Up
The results at baseline, discharge, 1-month, 3-month, and 12-month follow-up are summarized in Table 3. The MR was significantly reduced as compared with baseline at all follow-up points. Baseline MR grade of 2.9 ± 0.5 was reduced to 1.1 ± 0.6 at 12 months, demonstrating the sustained benefit of the Coapsys device. Figure 4
shows color Doppler transthoracic echocardiograms indicating the decrease in MR grade over the 12-month follow-up period. Clinical assessment of NYHA functional status demonstrated significant improvement from 2.5 ± 0.5 to 1.2 ± 0.4 at baseline and 12 months, respectively.
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Fig 4. Color Doppler transthoracic echocardiograms showing decrease of mitral regurgitation in a Coapsys-implanted patient at baseline (left), 3 months postimplant (middle), and 12 months postimplant (right).
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In a subset of patients (n = 8), the mitral inflow pattern was measured at baseline and 12 months to assess the effect of the Coapsys device on diastolic function. The mitral E-wave and A-wave velocities (cm/s) were 86.0 ± 10.9 and 55.0 ± 15.4 at baseline, and 74.8 ± 21.7 and 64.0 ± 19.5 at 12 months. The E/A ratio was then calculated as 1.66 ± 0.46 at baseline and 1.22 ± 0.38 at 12 months (p = 0.06 versus baseline), suggesting movement from a pseudonormal to a more normal diastolic filling pattern.
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Comment
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In most patients with ischemic functional MR, discrete structural alterations are normally absent. This supports the notion that the pathophysiologic mechanism probably involves a combination of valvular-subvalvular dysfunction related to annular dilatation, papillary muscle displacement, myocardial dysfunction, and ventricular remodeling. Currently accepted repair techniques most often involve annular reduction with rigid or semirigid rings. Although ring annuloplasty is a widely used means of MV repair and gives predictable early results, it only addresses annular septal lateral dimension [8], but not other mechanisms of functional MR [9]. McGee and colleagues [10] have reported a series where 28% of annuloplasty patients treated for ischemic functional MR have 3+ or 4+ MR 6 months after surgical repair. There have been several reports that emphasize the importance of treating the displacement of papillary muscles [11–13]. Additionally, ring annuloplasty adds operative risk with quoted operative mortality ranges of 4% to 15% [14, 15]. Invasive and mechanistic disadvantages of ring annuloplasty have led some investigators to attempt new methods of repair [16–19].
In this present series, we used the Coapsys mitral annuloplasty device to correct ischemic mitral regurgitation as an adjunct to CABG. Coapsys deployment and CABG were performed without CPB in all cases. The advantages of MV repair on a beating heart without CPB or an open heart procedure are significant. The possible complications associated with the use of CPB in a dysfunctional LV can be avoided. Additionally, it gives the advantage over ring annuloplasty of intraoperative evaluation of MR as the device is being sized.
In the present study, all patients had the Coapsys device placed after CABG because post-CABG MR grade determined whether or not the device was implanted. However, there is no inherent limitation to implanting the Coapsys device before, during, or after on-pump or off-pump CABG procedure. Coapsys positioning was considered when determining graft location and routing to ensure optimal device placement and eliminate graft interference.
Experimental work by Fukamachi and associates [20, 21] showed that the Coapsys device treats both: annular dilatation and displacement of papillary muscles. The Coapsys device was designed with a posterior pad that has superior and inferior heads. The superior head imparts shape change to the mitral annulus, while the inferior head, located between the papillary muscles, repositions the papillary muscles. This mechanistic function of the Coapsys may contribute to the sustained reduction of MR and clinical benefit on NYHA classification reported here. Therefore, the Coapsys device may provide significant advantages in the treatment of functional mitral regurgitation. There are few such devices reported in the literature [22, 23].
A limitation of this study is that it is a feasibility study with its inherent small number of patients in the analysis. Another significant limitation is the lack of a comparative prosthesis for MR reduction.
In conclusion, treatment with Coapsys is effective in significantly reducing ischemic mitral regurgitation and improving NYHA class in patients undergoing coronary artery bypass grafting. This reduction in mitral regurgitation and improvement in NYHA class in these patients is sustained at 12-month follow-up.
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Abstract
Introduction
