| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
ORIGINAL ARTICLE |
Department of Cardiothoracic Surgery,
1 Department of Cardiac Anesthesiology,
2 Department of Cardiology, CARE Hospital, The Institute of Medical Sciences, Hyderabad, India
Lokeswara R Sajja, MCh, Tel: +91 40 30418151, Fax: +91 40 23327025, Email: sajjalr{at}yahoo.com, CARE Hospital, The Institute of Medical Sciences, Road No.1, Banjara Hills, Hyderabad – 500 034, AP, India.
ABSTRACT
Mitral regurgitation is a frequent complication of ischemic heart disease. A retrospective study was performed on 127 patients with significant ischemic mitral regurgitation (regurgitant jet area 
6.0 cm2 and/or vena contracta width 0.70 cm) who underwent elective mitral valve repair between January 2001 and October 2007. Concomitant myocardial revascularization was carried out in all except one patient, and left ventricular restoration in 8. All patients had ring annuloplasty, with release of posterior mitral leaflet tethering in 21, leaflet resection in 7, chordal transfer in 3, and chordal shortening in 2. There were 4 (3.1%) hospital deaths. Two patients underwent successful mitral valve replacement for repair failure in the immediate postoperative period, and one had an unsuccessful valve replacement at 3 months. During a mean follow-up of 19.65 ± 13.21 months in 121 patients, 111 had trivial or no residual regurgitation, and 10 had mild regurgitation. Mitral valve repair for chronic ischemic mitral regurgitation is a reproducible technique with satisfactory early and mid-term outcomes and freedom from valve-related complications.
Key Words: Coronary Artery Bypass • Coronary Artery Disease • Heart Valve Prosthesis Implantation • Mitral Valve Insufficiency
INTRODUCTION
Mitral regurgitation (MR) is a frequent complication after acute myocardial infarction (MI) due to coronary artery disease.1–3 The impact of uncorrected significant MR on late outcomes after coronary artery bypass grafting (CABG) is well recognized. Most surgeons would attempt to correct ischemic mitral regurgitation (IMR) of moderate or greater severity by repairing or replacing the mitral valve.4,5 Surgical treatment of IMR is associated with high operative mortality and poor long-term survival. Choosing the most appropriate surgical treatment to maximize survival is made difficult by inconsistent classifications, a paucity of long-term data to compare alternatives, and lack of randomized trials of valve repair versus replacement. Gillinov and colleagues4 demonstrated that mitral valve repair was effective (at least in the short-term) in 97% of patients undergoing elective surgery for chronic IMR. Ring annuloplasty was employed in 98% of repairs, and was the sole valve maneuver in >80%.
PATIENTS AND METHODS
Data of 127 patients with significant chronic IMR (MR jet area 6.0 cm2 and/or vena contracta width 0.70 cm) who underwent CABG combined with mitral valve repair at a single institution from January 2001 through October 2007 were retrospectively analyzed. All patients had grade 3/4 or 4/4 MR on preoperative transthoracic echocardiography. Ischemic disease was characterized by at least one previous MI, associated regional wall motion abnormality, and normal leaflets. All patients had a regurgitant jet area 6.0 cm2 and/or vena contracta width 0.7 cm. Patients with functional IMR with Carpentier type IIIb and type I disease were included in the study. Preoperative characteristics are shown in Table 1
. The mean vena contracta width was 0.70 ± 0.28 cm.
|
4 cm2, moderate (2/4) with jet area 4–6 cm2, moderately severe (3/4) with jet area 6–8 cm2, and severe (4/4) with jet area >8 cm2.6 Echocardiographic characteristics of IMR included poor mitral leaflet coaptation and anterior and posterior leaflet tethering causing restriction of the leaflet with or without concomitant wall motion abnormalities, particularly at the posterolateral wall (Figure 1).7 The etiology of valve disease was determined from direct visual inspection of the mitral valve leaflets, annulus, chordae tendineae, and papillary muscles. Ischemic etiology was concluded if the mitral leaflet and chordae appeared normal but there were findings of papillary muscle infarction or thinning, or mitral annular dilatation associated with left ventricular (LV) dilatation and healed MI.8
|
. All except one patient underwent concomitant CABG. The left internal thoracic artery was used in 120 patients who needed revascularization of the left anterior descending coronary artery.
|
RESULTS
Postoperative outcomes are given in Table 3. Three of the 4 patients who died had combined mitral valve repair, CABG, and LV restoration. Two patients had moderate to severe MR in the immediate postoperative period and subsequently underwent successful mitral valve replacement during the same hospital admission. Two patients who had a standard left atriotomy and 7 who had a superior septal approach developed new-onset atrial fibrillation and were converted to sinus rhythm with antiarrhythmic medication before leaving the intensive care unit. Four patients who had atrial fibrillation preoperatively were also converted to sinus rhythm in the intensive care unit. Of 123 hospital survivors, 121 were followed up at regular intervals in outpatient clinics and by telephone interview. Pre-discharge transthoracic echocardiography was performed in 121 patients and revealed no or trivial MR in 111 patients and mild MR in 10 patients (Figure 2). One patient had mild MR at the time of discharge, which progressed to severe MR at 3 months and required mitral valve replacement; this patient died in the postoperative period. In patients with more than 1 year of echocardiographic follow-up,> mild MR was present in only one. None of the patients had bacterial endocarditis during the follow-up period.
|
|
The performance of mitral valve repair improved significantly from 1990 to 1999.10 The advantages of mitral valve repair compared with replacement have been well documented. These include maintenance of ventricular geometry and function, reduced requirement for chronic anticoagulation, excellent long-term durability, and reduced incidence of endocarditis. However, mitral valve repair beyond simple annuloplasty requires additional skills. An understanding of the 3-dimensional structure of the mitral valve, conceptualization of the effects of various repair techniques, and the ability to integrate and combine these techniques are necessary for successful repair.10 Mitral valve repair is more often undertaken with concomitant CABG than as an isolated procedure.10 Mitral valve repair has been shown to be superior to valve replacement in terms of 5-year survival.2 The mortality rate in our study is comparable to that in other series of repair for IMR.2,4,5 IMR results from remodeling of the ischemic LV, leading to displacement of the papillary muscles, annular dilatation, and therefore tethering of the mitral leaflets. This restricts mitral leaflet closure, preventing proper coaptation at the annulus.11 Mitral valve repair with an undersized annuloplasty ring works satisfactorily in most cases of functional IMR, but attention must be paid in interpreting the genesis and duration of the MR leak. If simple annular dilatation with incomplete mitral leaflet coaptation and Carpenter type I leaflet motion is the main culprit, and the leak is centrally directed due to "pseudo-prolapse" of the anterior mitral leaflet, which reflects restriction of the posterior leaflet, then it is likely that simple ring annuloplasty will work well and be fairly durable. Conversely, if the pattern of the IMR leak is complex, or substantial apical tenting of the leaflets is identified (Carpentier type IIIb restricted leaflet motion), or a lateral wall infarct is present, then simple ring annuloplasty may not be the most prudent course of action. The most important goal in valve repair is to reduce and fix the annular dimension in the anterior-posterior (or septal-lateral) axis, not the commissure-commissure axis. Although partially or completely flexible rings perform satisfactorily, this goal may be best accomplished using a rigid ring in patients with IMR.12
In chronic IMR, valve repair was reported to be possible in 90% of cases, and freedom from reoperation was high.13 Combined mitral downsizing and CABG gave excellent results: only minimal residual MR, significantly reduced left atrial dimensions, and increased LV contractility due to reverse remodeling.14 We repaired the mitral valve in 127 of 142 patients (89%) with chronic IMR. Mortality was higher in patients who underwent combined valve repair and LV restoration (3/8). A similar high mortality rate was reported by Sartipy and colleagues15 in patients with mild to severe MR undergoing mitral valve repair in conjunction with surgical ventricular restoration. Mitral valve repair is superior to replacement when associated with coronary artery disease, in terms of perioperative morbidity and hospital mortality. Although preservation of the subannular apparatus with mitral valve replacement has a theoretical advantage in terms of ventricular function, mitral repair clearly adds a survival benefit in patients with concomitant ischemic disease.16 We found the incidence of grade 3 or 4 MR was higher after inferior than anterior or anteroseptal MI, as noted by others.2 Inferior MI causes less extensive ischemia but direct involvement of important components of the mitral valve apparatus, including the basal inferior LV wall adjacent to the posterior papillary muscle and mitral valve annulus.
Although mid-term results of ring annuloplasty are encouraging, concern has been raised over the progression of MR after repair, and the associated poor prognosis. Crabtree and colleagues17 reported that 28% of patients in whom follow-up echocardiographic data were available had 3+ to 4+ MR after 20 ± 25 months, with actuarial 5-year survival of 36% in this group. Tahta and colleagues18 in a large single-center surgical series, reported recurrent moderate or greater MR in 30% after 3 years. Hung and colleagues19 hypothesized that recurrent MR after ring annuloplasty relates to continued LV remodeling, and emphasized the dynamic relationship of MR to the LV. They found that MR increased from mild to moderate in early to late postoperative stages, without a significant change in LV ejection fraction, and demonstrated that changes in MR paralleled increases in LV volume and sphericity index in end-systole and end-diastole, although the only independent predictor of late postoperative MR was LV sphericity index at end-systole. Kuwahara and colleagues20 showed that increased posterior leaflet tethering was the primary determinant of late MR after anuloplasty, and thus recommended further downsizing of the anuloplasty device.20 With the availability of long-term outcomes of ring annuloplasty, we need to follow up our patients closely by echocardiography. As recurrent MR after ring anuloplasty relates to LV remodeling, approaches that also alleviate ventricular remodeling could potentially be part of a more comprehensive and effective management strategy for IMR. More than 90% of our patients had no or trivial MR at discharge, and we expect them to have a durable repair because residual MR is a risk factor for late failure.
This study had many of the limitations reported in other retrospective studies (non-randomized, single-institution). It addressed only patients who underwent mitral valve repair for IMR and did not compare them to those treated medically or by CABG alone. The study did not compare the outcomes with those of contemporaneous patients who underwent mitral valve replacement for IMR, and the long-term outcomes are not yet available because mean follow-up was only 19.65 months. However, it was concluded that mitral valve repair for chronic IMR is a reproducible technique with satisfactory early and mid-term outcomes and freedom from valve-related complications. Remodeling annuloplasty was the sole procedure in three-quarters of the patients. Release of tethering of the posterior mitral leaflet, when indicated, reduced residual MR after repair. Prospective randomized studies are required to confirm the superiority of the mitral valve repair over valve replacement.
ACKNOWLEDGMENTS
We sincerely thank A Nadamuni Naidu, MSc (Stat), Head, Department of Statistics, (Rtd), National Institute of Nutrition, ICMR, Hyderabad, for statistical advice and analysis, and G Arun Babu MBA, of STAR Hospitals, Hyderabad, for the help in preparing the manuscript.
Presented at the 16th Annual Meeting of the Asian Society for Cardiovascular and Thoracic Surgery, Singapore, March 13–16, 2008.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:29-34
© 2009 by SAGE Publications
DOI: 10.1177/0218492309102508
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
