Efficacy of left ventricular restoration with mitral valve surgery for endstage ischemic cardiomyopathy
http://www.100md.com
《血管的通路杂志》
a Cardiovascular Surgery, Hayama Heart Center, 1898 Shimoyamaguchi Hayama, Kanagawa, 240-0116, Japan
b The Cardiovascular Institute, Tokyo, Japan
Presented at the joint 19th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 13th Annual Meeting of the European Society of Thoracic Surgeons, Barcelona, Spain, September 25–28, 2005.
Abstract
Patients with ischemic cardiomyopathy (ICM) are at an extremely high risk of death and ischemic events. This study aims to evaluate the impact of left ventricular restoration (LVR) and mitral valve surgery on the cardiac and clinical functional status of the patients with ICM. Twenty-six patients (46–80 years, mean: 64 years) with severely dilated heart (left ventricular end-systolic volume index: LVESVI 100 ml/m2) who had coronary artery bypass grafting (2.8±1.3), mitral valve surgery, and LVR were enrolled in this study. Left ventricular end-diastolic volume index and LVESVI significantly decreased (from 169±44 to 130±41 ml/m2, P=0.0005, from 120±33 to 89±43 ml/m2, P=0.0012). Left ventricular ejection fraction showed no change. MR showed significant improvement (from 2.7±0.6 to 1.0±0.4, P<0.0001) and NYHA functional class showed improvement (from 3.2±0.8 to 1.5±0.9, P<0.0001). A 5-year survival rate was 71.2%. In conclusion, this aggressive approach with LVR aiming to treat end-stage ICM by relief of ischemia, reduction of LV wall tension by decreasing LV volume and stopping mitral leak, is effective for LV volume reduction and improvement of clinical functional status.
Key Words: Ischemic mitral regurgitation; Left ventricular restoration; Ischemic cardiomyopathy; Mitral valve annuloplasty
1. Introduction
Ischemic cardiomyopathy (ICM) with ischemic mitral regurgitation (IMR) is caused by myocardial infarction and is an ominous disease that is associated with poor long-term survival irrespective of treatment [1]. The leaflets and subvalvular apparatus are by definition normal and IMR is a manifestation of postinfarction ventricular remodeling and is a disease of the myocardium (both infarcted and normally perfused). Recent clinical [2] and laboratory studies [3,4] are beginning to improve our understanding and approach to this vexing clinical problem. Because it has been clearly shown that patients with ICM and mitral regurgitation have poor long-term prognosis [5], and patients with increased left ventricular volume have worse outcome than those with normal ventricular volume [6–8], IMR and large left ventricle are the major issues that should be solved while treating ICM. The aim of this study is to evaluate the impact of left ventricular restoration (LVR) and mitral valve surgery on the cardiac function and clinical functional status in the patients with end-stage ICM.
2. Subjects and methods
From March 2000 to August 2005, twenty-six patients (age from 46 to 80 years, mean age of 64 years, female: 3, male: 23) with severely dilated heart, namely end-stage ICM (LV end-systolic volume index: LVESVI 100 ml/m2 or left ventricular diastolic dimension: LVDd 70 mm), received LVR operation, mitral valve surgery, and coronary artery bypass grafting (CABG: 2.8±1.3 grafts).
Preoperative examinations consist of an echocardiogram with color kinesis (HP SONOS 5500, Hewlett-Pakard company, Anover, MA, USA), cardiac catheterization, coronary angiogram, cine magnetic resonance image (MRI, Imatron. Inc., South San Francisco, CA, USA), gated cardiac pool scan and quantitated gated SPECT (QGS). Myocardial viability and LV wall motion were detected by those examinations. According to the selection of surgical procedure based on the pre-operative examination and intra-operative echocardiogram as described previously [9], LVR operation was performed, which consisted of antero-septal exclusion with oval patch as endoventricular circular patch plasty (EVCPP) described by Dor [6], when the LV akinesis was severe in antero-apical wall, or with larger patch as large antero-septal ventricular exclusion (SAVE) reported by us [9], or overlapping method excluding small antero-septal region which is similar to SAVE without using patch. Exclusion part was precisely planned on the basis of pre-operative assessment of LV wall motion and viability using MRI, QGS and echocardiogram examination, and most importantly, intra-operative echocardiogram test contributed to the final decision because the wall motion and the thickness of the LV muscle changed after the reduction of LV volume during cardiopulmonary bypass (CPB). As the most akinetic part was excluded with LVR, Dor's operation, SAVE operation, or overlapping operation were appropriately chosen to make LV shape more ellipsoidal but not spherical.
Mitral regurgitation was assessed with color Doppler and severity was graded as mild (grade-1), moderate (grade-2), moderate to severe (grade-3), or severe (grade-4). During the operation, intra-operative echocardiogram was applied to detect the lesion of MR and cause of MR. After the CPB was instituted, the LV volume was reduced or overloaded (volume reduction and loading test). Rapid transfusion via arterial cannulation was initiated until systolic pulmonary artery pressure rose to the level of pre-operative pressure in cardiac catheterization value. Then the volume was reduced until the systemic pressure reached 50–60 mmHg. The degree of MR became none or mild after the reduction of the volume and it was grade 3–4 with volume loading when the cause of MR was simple mitral annular dilatation or functional MR. Thus, LV volume loading test was carefully carried out, if IMR was less than grade-2 or fluctuating, which led us to choose an aggressive approach. Standard CPB was started with 34 °C and intermittent antegrade tepid blood cardioplegia was used for cardiac arrest. After complete coronary revascularization and mitral valve surgery, the aortic cross clamp was removed to start heart beating. Under the beating heart optimal type of LV restoration was performed.
For mitral valve surgery, annular dilatation was repaired using downsizing circumferential ring (Carpentier-Edwards Physio Ring) by two sizes from the size measured in a classical way. When incomplete repair was remaining more than grade-2 MR by intra-operative echo examination, mitral valve was replaced. After weaning from the pump, cardiac echocardiogram is repeated to judge the mitral repair. Mitral annuloplasty (MAP) was judged successful when the MR became grade-0 or the area of mitral regurgitation was less than 2 cm2 under systemic pressure over 90–100 mmHg.
The LV volume and diameter were measured by LV graphy, QGS, and echocardiogram. After discharge from hospital all patients continued medical treatment and they were followed up and received re-admission for re-examination every 6 months after surgery at the patients' convenience if coming a long distance.
Statistical analysis: Values were expressed as mean±standard deviation (S.D.). Statistical analysis comparing pre- and post-operative variables was performed with paired t-test. Kaplan–Meier estimation was used to calculate cumulative survival rate. A P<0.05 was considered significant.
3. Results
Operative procedures are summarized in Table 1. Each LVR procedure including Dor, SAVE, or overlapping operation was selected according to the most akinetic area, thus the site selection was appropriately performed to make LV shape more ellipsoidal. Patients with a history of ventricular tachycardia had LV cryoablation according to the LV mapping or just on the border zone between scar and normal tissue or on the bases of both papillary muscles. Biventricular pacing wires and pacemaker were placed if QRS complex of ECG was wider than 130 ms. One mitral valve replacement was done instead of repair in this series. There was no patient who received mitral valve replacement for recurrent MR after MAP. Tricuspid valve was repaired with either modified DeVega procedure (2) or Carpentier-Edwards Classic Ring annuloplasty (5) in 7 patients if tricuspid regurgitation was greater than grade-2.
3.1. Cardiac function and changes in LV volume
Preoperative and postoperative cardiac function (Left ventricular end-diastolic volume index: LVEDVI ml/m2; Left ventricular end-systolic volume index: LVESVI ml/m2; Left ventricular ejection fraction; EF %) measured by LVgraphy, QGS and echocardiogram are shown in Table 2. Cardiac catheter data such as mean pulmonary arterial pressure (mPA), left ventricle enddiastolic pressure (LVEDP), cardiac index (CI) are shown in Table 3.
LVEDVI as well as LVESVI significantly decreased after operation. LVEF showed some improvement. However, mean PA, LVEDP, and CI did not show any improvement after operation.
3.2. Changes in BNP and NYHA functional class and MR
NYHA functional class, brain natriuretic peptide (BNP: one of the humoral factors of index for cardiac reserve and indicator of prognosis), and degree of mitral regurgitation are shown in Table 4. BNP showed significant decrease after operation.
The follow-up analysis showed that 26 patients improved NYHA functional class 1 or 2 (III/IV: 7/12 to III/IV; 1/2), while operative death was in one (3.6%), and late deaths were two (7.7%). The causes of late deaths were intractable congestive heart failure in one, and ventricular arrhythmia in one. The 5-year survival rate was 71.2%.
MR showed significant improvement after operation (from grade-0=0, grade-1=0, grade 2=9, grade 3=15, grade-4=2 to grade-0=2, grade-1=22, grade-2=2, grade-3=0, grade-4=0). Residual grade-2 MR was found in two patients without symptoms (2/26: 7.7%), who were carefully followed up without reoperation.
LV shape assessed by QGS, MR angio, and LVG revealed that 16/26 (62%) patients gained more ellipsoidal shapes after operation.
4. Discussion
In this report, ICM is defined as global akinesis of LV (LV ejection fraction was less than 30%) due to ischemia and LV remodeling. Ischemic mitral regurgitation and akinetic large ventricle are the major issues which should be solved when surgery for end-stage ICM is indicated.
There were significant improvements of LV volume (reduced systolic and diastolic volumes) and also clinical status, judging from NYHA functional class as well as BNP level after LVR with MAP. Ejection fraction showed some improvement, however, in the case with mitral regurgitation it was theoretically inappropriate to evaluate the LV function by EF, because patients with MR before operation seemed to have better contractile function than real one. Operative mortality was 3.6% and five-year survival rate showed a favorable outcome of 71.2%.
The MR is not always associated with ischemic cardiac disease, although the heart failure is rapidly deteriorated with the occurrence of MR during natural history. The mechanisms of functional mitral regurgitation have been reported [2–4]. The mechanisms are mainly LV dilatation and distortion (LV geometric distortion), systolic restriction of mitral leaflets (Carpentier type III-B) due to the tethering of mitral leaflets, annular dilatation, and papillary muscle dysfunction. Therefore, even if the papillary muscle is not involved in the ischemic region, LV dilatation and remodeling of spherical shape causes severe MR. Bolling et al. [10] reported that mitral repair was effective to improve clinical symptom in patients with dilated cardiomyopathy and severe MR. Dion et al. [11] used an intra-operative dynamic testing using transesophageal echo, and associating a loading test and an afterload test. If MR was caused by mainly geometric change and annular dilatation due to LV dilatation and severe wall tension, MR became none or less than grade-1 by volume reduction and regained more than grade-3 with volume loading with cardiopulmonary bypass as we mentioned [9]. The volume loading and reducing test was useful to decide the operative technique and whether or not functional ischemic MR could be repaired with simple annuloplasty using two downsized semi-rigid circular rings.
A considerable number of reports addressing mechanism of ischemic MR derived from clinical data [2] and ovine studies [3,4], and great suggestions for surgery to solve this important issue have come out. Ischemic MR results from remodeling of ischemic LV leading to displacement of papillary muscle, annular dilatation, and therefore, tethering of mitral leaflet, which restricts mitral leaflet coaptation. As remodeling is progressing, annular compensation for ventricular dilatation may not be durable [4,12]. Tiabian et al. [12] suggested that both an annular and aggressive subannular approach (correct lateral displacement of posterior papillary muscle) should be considered, although undersizing the septal-lateral (anterior-posterior) annulus dimension could simultaneously correct lateral displacement of the papillary muscle in certain degree. Calafiore et al. [13] reported the necessity of a more radical repair procedure (realignment of papillary muscle geometry inside the ventricle) than annuloplasty, which is required to correct extensively tethered leaflets such as LV restoration and so on, and Menicannti et al. [14] reported that the mitral annular repair was perhaps the first mechanism that relieved volume overload, but the improved LV geometry was essential to maintain the efficacy of repair. Moreover, 20% of patients show persistent or recurrent MR despite annuloplasty [13,15], which also adversely affects patients outcome after surgery [10,14]. In our series, MR was found only in 2/26 (8%), which is a very low recurrence rate for these end-stage ICM. LV ellipsoidal shape might play an important role to prevent recurrent MR. Because poor LV function is often considered an important factor for late recurrence of ischemic MR in patients after ring annuloplasty, LVR [7–9] must be indicated for those poor LV patients.
After we introduced circumferential semi-rigid ring (Carpentier-Edwards Physio Ring) with smaller size (two size down ring: 26 or 28 mm), grade-2 MR persisted in two patients without symptom and without re-operation. We believe that the benefits of LVR are firstly, reduction in LV wall tension by LV volume reduction which would lead to improved LV wall motion, secondly, ellipsoidal shape that is theoretically less energy loss for contraction, and lastly, low recurrence rate of MR. This study confirmed that our surgical strategy to treat patients of end-stage ICM with LVR as well as MAP was satisfying.
Limitation of this study is, of course, a retrospective study performed in one institution and is not a randomized study. However, randomization was difficult in this clinical study.
In conclusion, this combined radical surgical approach aiming to treat end-stage ICM with relief of ischemia, reduction of LV wall tension by decreasing LV volume and reduction of volume overload by repairing mitral valve, could contribute to the surviving patients' benefits with improving their clinical functional class thereby their QOL.
Appendix. Conference discussion
Dr Tsang: I'm very intrigued. What do you think the more important approach, the coronary artery bypass grafting, the mitral valve repair or the LV restoration, in the management of this very difficult group of patients
Dr Nomura: I believe, if the ventricle is large, left ventricle restoration must be necessary. And, if the ventricle is not large, but with mitral regurgitation, mitral repair must be done.
However, the coronary artery bypass has to be done basically. All the muscles must receive sufficient flow from the coronaries, at first, then we have to think about the second and third choice.
References
Miller DC. Ischemic mitral regurgitation redux — to repair or to replace. J Thorac Cardiovasc Surg 2001; 122:1059–1062.
Otsuji Y, Handschumacher MD, Schwammenthal E, Jiang L, Song JK, Guerrero JL, Vlahakes GJ, Levine RA. Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry. Circulation 1997; 96:1999–2008.
Langer F, Rodriguez F, Ortiz S, Cheng A, Nguyen TC, Zasio MK, Liang D, Daughters GT, Ingels NB, Miller DC. Subvalvular repair: the key to repairing ischemic mitral regurgitation. Circulation 2005; 112:1383–1389.
Tibayan FA, Rodriguez F, Zasio MK, Bailey L, Liang D, Daughters GT, Langer F, Ingels NB Jr, Miller DC. Geometric distortions of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation. Circulation 2003; 108:Suppl_1II 116–121.
Grigioni F, Enriquez-Sarano M, Zehr KJ, Bailey KR, Tajik AJ. Ischemic mitral regurgitation: long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 2001; 103:1759–1764.
Dor V, Sabatier M, Di Donato M, Montiglio F, Toso A, Maioli M. Efficacy of endoventricular patch plasty in large postinfarction akinetic scar and severe left ventricular dysfunction: comparison with a series of large dyskinetic scars. J Thorac Cardiovasc Surg 1998; 116:50–59.
Yamaguchi A, Kawahito K, Adachi H, Ino T. The outcome and criteria for mitral valve surgery in patients with ischemic mitral regurgitation. Jpn J Thorac Cardiovasc Surg 2003; 51:407–412.
Maxey TS, Reece TB, Ellman PI, Butler PD, Kern JA, Tribble CG, Kron IL. Coronary artery bypass with ventricular restoration is superior to coronary artery bypass alone in patients with ischemic cardiomyopathy. J Thorac Cardiovasc Surg 2004; 127:428–434.
Isomura T, Suma H, Horii T, Sato T, Kikuchi N. Partial left ventriculectomy, ventriculoplasty or valvular surgery for idiopathic dilated cardiomyopathy – the role of intra-operative echocardiography. Eur J Cardio-thorac Surg 2000; 17:239–245.
Bolling SF, Pagani FD, Deeb GM, Bach DS. Intermediate-term outcome of mitral reconstruction in cardiomyopathy. J Thorac Cardiovasc Surg 1998; 115:381–386. discussion 387–388.
Braun J, Bax JJ, Versteegh MI, Voigt PG, Holman ER, Klautz RJ, Boersma E, Dion RA. Preoperative left ventricular dimensions predict reverse remodeling following restrictive mitral annuloplasty in ischemic mitral regurgitation. Eur J Cardiothorac Surg 2005; 27:847–853.
Tibayan FA, Rodriguez F, Langer F, Zasio MK, Bailey L, Liang D, Daughters GT, Ingels NB, Miller DC. Annular or subvalvular approach to chronic ischemic mitral regurgitation. J Thorac Cardiovasc Surg 2005; 129:1266–1275.
Calafiore AM, Gallina S, Di Mauro M, Gaeta F, Iaco AL, D'Alessandro S, Mazzei V, Di Giammarco G. Mitral valve procedure in dilated cardiomyopathy: repair or replacement. Ann Thorac Surg 2001; 71:1146–1152. discussion 1152–1153.
Menicanti L, Di Donato M, Frigiola A, Buckberg G, Santambrogio C, Ranucci M, Santo D. Ischemic mitral regurgitation: intraventricular papillary muscle imbrication without mitral ring during left ventricular restoration. J Thorac Cardiovasc Surg 2002; 123:1041–1050.
Tahta SA, Oury JH, Maxwell JM, Hiro SP, Duran CM. Outcome after mitral valve repair for functional ischemic mitral regurgitation. J Heart Valve Dis 2002; 11:11–18. discussion 18–19.(Fumikazu Nomura, Tadashi )
b The Cardiovascular Institute, Tokyo, Japan
Presented at the joint 19th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 13th Annual Meeting of the European Society of Thoracic Surgeons, Barcelona, Spain, September 25–28, 2005.
Abstract
Patients with ischemic cardiomyopathy (ICM) are at an extremely high risk of death and ischemic events. This study aims to evaluate the impact of left ventricular restoration (LVR) and mitral valve surgery on the cardiac and clinical functional status of the patients with ICM. Twenty-six patients (46–80 years, mean: 64 years) with severely dilated heart (left ventricular end-systolic volume index: LVESVI 100 ml/m2) who had coronary artery bypass grafting (2.8±1.3), mitral valve surgery, and LVR were enrolled in this study. Left ventricular end-diastolic volume index and LVESVI significantly decreased (from 169±44 to 130±41 ml/m2, P=0.0005, from 120±33 to 89±43 ml/m2, P=0.0012). Left ventricular ejection fraction showed no change. MR showed significant improvement (from 2.7±0.6 to 1.0±0.4, P<0.0001) and NYHA functional class showed improvement (from 3.2±0.8 to 1.5±0.9, P<0.0001). A 5-year survival rate was 71.2%. In conclusion, this aggressive approach with LVR aiming to treat end-stage ICM by relief of ischemia, reduction of LV wall tension by decreasing LV volume and stopping mitral leak, is effective for LV volume reduction and improvement of clinical functional status.
Key Words: Ischemic mitral regurgitation; Left ventricular restoration; Ischemic cardiomyopathy; Mitral valve annuloplasty
1. Introduction
Ischemic cardiomyopathy (ICM) with ischemic mitral regurgitation (IMR) is caused by myocardial infarction and is an ominous disease that is associated with poor long-term survival irrespective of treatment [1]. The leaflets and subvalvular apparatus are by definition normal and IMR is a manifestation of postinfarction ventricular remodeling and is a disease of the myocardium (both infarcted and normally perfused). Recent clinical [2] and laboratory studies [3,4] are beginning to improve our understanding and approach to this vexing clinical problem. Because it has been clearly shown that patients with ICM and mitral regurgitation have poor long-term prognosis [5], and patients with increased left ventricular volume have worse outcome than those with normal ventricular volume [6–8], IMR and large left ventricle are the major issues that should be solved while treating ICM. The aim of this study is to evaluate the impact of left ventricular restoration (LVR) and mitral valve surgery on the cardiac function and clinical functional status in the patients with end-stage ICM.
2. Subjects and methods
From March 2000 to August 2005, twenty-six patients (age from 46 to 80 years, mean age of 64 years, female: 3, male: 23) with severely dilated heart, namely end-stage ICM (LV end-systolic volume index: LVESVI 100 ml/m2 or left ventricular diastolic dimension: LVDd 70 mm), received LVR operation, mitral valve surgery, and coronary artery bypass grafting (CABG: 2.8±1.3 grafts).
Preoperative examinations consist of an echocardiogram with color kinesis (HP SONOS 5500, Hewlett-Pakard company, Anover, MA, USA), cardiac catheterization, coronary angiogram, cine magnetic resonance image (MRI, Imatron. Inc., South San Francisco, CA, USA), gated cardiac pool scan and quantitated gated SPECT (QGS). Myocardial viability and LV wall motion were detected by those examinations. According to the selection of surgical procedure based on the pre-operative examination and intra-operative echocardiogram as described previously [9], LVR operation was performed, which consisted of antero-septal exclusion with oval patch as endoventricular circular patch plasty (EVCPP) described by Dor [6], when the LV akinesis was severe in antero-apical wall, or with larger patch as large antero-septal ventricular exclusion (SAVE) reported by us [9], or overlapping method excluding small antero-septal region which is similar to SAVE without using patch. Exclusion part was precisely planned on the basis of pre-operative assessment of LV wall motion and viability using MRI, QGS and echocardiogram examination, and most importantly, intra-operative echocardiogram test contributed to the final decision because the wall motion and the thickness of the LV muscle changed after the reduction of LV volume during cardiopulmonary bypass (CPB). As the most akinetic part was excluded with LVR, Dor's operation, SAVE operation, or overlapping operation were appropriately chosen to make LV shape more ellipsoidal but not spherical.
Mitral regurgitation was assessed with color Doppler and severity was graded as mild (grade-1), moderate (grade-2), moderate to severe (grade-3), or severe (grade-4). During the operation, intra-operative echocardiogram was applied to detect the lesion of MR and cause of MR. After the CPB was instituted, the LV volume was reduced or overloaded (volume reduction and loading test). Rapid transfusion via arterial cannulation was initiated until systolic pulmonary artery pressure rose to the level of pre-operative pressure in cardiac catheterization value. Then the volume was reduced until the systemic pressure reached 50–60 mmHg. The degree of MR became none or mild after the reduction of the volume and it was grade 3–4 with volume loading when the cause of MR was simple mitral annular dilatation or functional MR. Thus, LV volume loading test was carefully carried out, if IMR was less than grade-2 or fluctuating, which led us to choose an aggressive approach. Standard CPB was started with 34 °C and intermittent antegrade tepid blood cardioplegia was used for cardiac arrest. After complete coronary revascularization and mitral valve surgery, the aortic cross clamp was removed to start heart beating. Under the beating heart optimal type of LV restoration was performed.
For mitral valve surgery, annular dilatation was repaired using downsizing circumferential ring (Carpentier-Edwards Physio Ring) by two sizes from the size measured in a classical way. When incomplete repair was remaining more than grade-2 MR by intra-operative echo examination, mitral valve was replaced. After weaning from the pump, cardiac echocardiogram is repeated to judge the mitral repair. Mitral annuloplasty (MAP) was judged successful when the MR became grade-0 or the area of mitral regurgitation was less than 2 cm2 under systemic pressure over 90–100 mmHg.
The LV volume and diameter were measured by LV graphy, QGS, and echocardiogram. After discharge from hospital all patients continued medical treatment and they were followed up and received re-admission for re-examination every 6 months after surgery at the patients' convenience if coming a long distance.
Statistical analysis: Values were expressed as mean±standard deviation (S.D.). Statistical analysis comparing pre- and post-operative variables was performed with paired t-test. Kaplan–Meier estimation was used to calculate cumulative survival rate. A P<0.05 was considered significant.
3. Results
Operative procedures are summarized in Table 1. Each LVR procedure including Dor, SAVE, or overlapping operation was selected according to the most akinetic area, thus the site selection was appropriately performed to make LV shape more ellipsoidal. Patients with a history of ventricular tachycardia had LV cryoablation according to the LV mapping or just on the border zone between scar and normal tissue or on the bases of both papillary muscles. Biventricular pacing wires and pacemaker were placed if QRS complex of ECG was wider than 130 ms. One mitral valve replacement was done instead of repair in this series. There was no patient who received mitral valve replacement for recurrent MR after MAP. Tricuspid valve was repaired with either modified DeVega procedure (2) or Carpentier-Edwards Classic Ring annuloplasty (5) in 7 patients if tricuspid regurgitation was greater than grade-2.
3.1. Cardiac function and changes in LV volume
Preoperative and postoperative cardiac function (Left ventricular end-diastolic volume index: LVEDVI ml/m2; Left ventricular end-systolic volume index: LVESVI ml/m2; Left ventricular ejection fraction; EF %) measured by LVgraphy, QGS and echocardiogram are shown in Table 2. Cardiac catheter data such as mean pulmonary arterial pressure (mPA), left ventricle enddiastolic pressure (LVEDP), cardiac index (CI) are shown in Table 3.
LVEDVI as well as LVESVI significantly decreased after operation. LVEF showed some improvement. However, mean PA, LVEDP, and CI did not show any improvement after operation.
3.2. Changes in BNP and NYHA functional class and MR
NYHA functional class, brain natriuretic peptide (BNP: one of the humoral factors of index for cardiac reserve and indicator of prognosis), and degree of mitral regurgitation are shown in Table 4. BNP showed significant decrease after operation.
The follow-up analysis showed that 26 patients improved NYHA functional class 1 or 2 (III/IV: 7/12 to III/IV; 1/2), while operative death was in one (3.6%), and late deaths were two (7.7%). The causes of late deaths were intractable congestive heart failure in one, and ventricular arrhythmia in one. The 5-year survival rate was 71.2%.
MR showed significant improvement after operation (from grade-0=0, grade-1=0, grade 2=9, grade 3=15, grade-4=2 to grade-0=2, grade-1=22, grade-2=2, grade-3=0, grade-4=0). Residual grade-2 MR was found in two patients without symptoms (2/26: 7.7%), who were carefully followed up without reoperation.
LV shape assessed by QGS, MR angio, and LVG revealed that 16/26 (62%) patients gained more ellipsoidal shapes after operation.
4. Discussion
In this report, ICM is defined as global akinesis of LV (LV ejection fraction was less than 30%) due to ischemia and LV remodeling. Ischemic mitral regurgitation and akinetic large ventricle are the major issues which should be solved when surgery for end-stage ICM is indicated.
There were significant improvements of LV volume (reduced systolic and diastolic volumes) and also clinical status, judging from NYHA functional class as well as BNP level after LVR with MAP. Ejection fraction showed some improvement, however, in the case with mitral regurgitation it was theoretically inappropriate to evaluate the LV function by EF, because patients with MR before operation seemed to have better contractile function than real one. Operative mortality was 3.6% and five-year survival rate showed a favorable outcome of 71.2%.
The MR is not always associated with ischemic cardiac disease, although the heart failure is rapidly deteriorated with the occurrence of MR during natural history. The mechanisms of functional mitral regurgitation have been reported [2–4]. The mechanisms are mainly LV dilatation and distortion (LV geometric distortion), systolic restriction of mitral leaflets (Carpentier type III-B) due to the tethering of mitral leaflets, annular dilatation, and papillary muscle dysfunction. Therefore, even if the papillary muscle is not involved in the ischemic region, LV dilatation and remodeling of spherical shape causes severe MR. Bolling et al. [10] reported that mitral repair was effective to improve clinical symptom in patients with dilated cardiomyopathy and severe MR. Dion et al. [11] used an intra-operative dynamic testing using transesophageal echo, and associating a loading test and an afterload test. If MR was caused by mainly geometric change and annular dilatation due to LV dilatation and severe wall tension, MR became none or less than grade-1 by volume reduction and regained more than grade-3 with volume loading with cardiopulmonary bypass as we mentioned [9]. The volume loading and reducing test was useful to decide the operative technique and whether or not functional ischemic MR could be repaired with simple annuloplasty using two downsized semi-rigid circular rings.
A considerable number of reports addressing mechanism of ischemic MR derived from clinical data [2] and ovine studies [3,4], and great suggestions for surgery to solve this important issue have come out. Ischemic MR results from remodeling of ischemic LV leading to displacement of papillary muscle, annular dilatation, and therefore, tethering of mitral leaflet, which restricts mitral leaflet coaptation. As remodeling is progressing, annular compensation for ventricular dilatation may not be durable [4,12]. Tiabian et al. [12] suggested that both an annular and aggressive subannular approach (correct lateral displacement of posterior papillary muscle) should be considered, although undersizing the septal-lateral (anterior-posterior) annulus dimension could simultaneously correct lateral displacement of the papillary muscle in certain degree. Calafiore et al. [13] reported the necessity of a more radical repair procedure (realignment of papillary muscle geometry inside the ventricle) than annuloplasty, which is required to correct extensively tethered leaflets such as LV restoration and so on, and Menicannti et al. [14] reported that the mitral annular repair was perhaps the first mechanism that relieved volume overload, but the improved LV geometry was essential to maintain the efficacy of repair. Moreover, 20% of patients show persistent or recurrent MR despite annuloplasty [13,15], which also adversely affects patients outcome after surgery [10,14]. In our series, MR was found only in 2/26 (8%), which is a very low recurrence rate for these end-stage ICM. LV ellipsoidal shape might play an important role to prevent recurrent MR. Because poor LV function is often considered an important factor for late recurrence of ischemic MR in patients after ring annuloplasty, LVR [7–9] must be indicated for those poor LV patients.
After we introduced circumferential semi-rigid ring (Carpentier-Edwards Physio Ring) with smaller size (two size down ring: 26 or 28 mm), grade-2 MR persisted in two patients without symptom and without re-operation. We believe that the benefits of LVR are firstly, reduction in LV wall tension by LV volume reduction which would lead to improved LV wall motion, secondly, ellipsoidal shape that is theoretically less energy loss for contraction, and lastly, low recurrence rate of MR. This study confirmed that our surgical strategy to treat patients of end-stage ICM with LVR as well as MAP was satisfying.
Limitation of this study is, of course, a retrospective study performed in one institution and is not a randomized study. However, randomization was difficult in this clinical study.
In conclusion, this combined radical surgical approach aiming to treat end-stage ICM with relief of ischemia, reduction of LV wall tension by decreasing LV volume and reduction of volume overload by repairing mitral valve, could contribute to the surviving patients' benefits with improving their clinical functional class thereby their QOL.
Appendix. Conference discussion
Dr Tsang: I'm very intrigued. What do you think the more important approach, the coronary artery bypass grafting, the mitral valve repair or the LV restoration, in the management of this very difficult group of patients
Dr Nomura: I believe, if the ventricle is large, left ventricle restoration must be necessary. And, if the ventricle is not large, but with mitral regurgitation, mitral repair must be done.
However, the coronary artery bypass has to be done basically. All the muscles must receive sufficient flow from the coronaries, at first, then we have to think about the second and third choice.
References
Miller DC. Ischemic mitral regurgitation redux — to repair or to replace. J Thorac Cardiovasc Surg 2001; 122:1059–1062.
Otsuji Y, Handschumacher MD, Schwammenthal E, Jiang L, Song JK, Guerrero JL, Vlahakes GJ, Levine RA. Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry. Circulation 1997; 96:1999–2008.
Langer F, Rodriguez F, Ortiz S, Cheng A, Nguyen TC, Zasio MK, Liang D, Daughters GT, Ingels NB, Miller DC. Subvalvular repair: the key to repairing ischemic mitral regurgitation. Circulation 2005; 112:1383–1389.
Tibayan FA, Rodriguez F, Zasio MK, Bailey L, Liang D, Daughters GT, Langer F, Ingels NB Jr, Miller DC. Geometric distortions of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation. Circulation 2003; 108:Suppl_1II 116–121.
Grigioni F, Enriquez-Sarano M, Zehr KJ, Bailey KR, Tajik AJ. Ischemic mitral regurgitation: long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 2001; 103:1759–1764.
Dor V, Sabatier M, Di Donato M, Montiglio F, Toso A, Maioli M. Efficacy of endoventricular patch plasty in large postinfarction akinetic scar and severe left ventricular dysfunction: comparison with a series of large dyskinetic scars. J Thorac Cardiovasc Surg 1998; 116:50–59.
Yamaguchi A, Kawahito K, Adachi H, Ino T. The outcome and criteria for mitral valve surgery in patients with ischemic mitral regurgitation. Jpn J Thorac Cardiovasc Surg 2003; 51:407–412.
Maxey TS, Reece TB, Ellman PI, Butler PD, Kern JA, Tribble CG, Kron IL. Coronary artery bypass with ventricular restoration is superior to coronary artery bypass alone in patients with ischemic cardiomyopathy. J Thorac Cardiovasc Surg 2004; 127:428–434.
Isomura T, Suma H, Horii T, Sato T, Kikuchi N. Partial left ventriculectomy, ventriculoplasty or valvular surgery for idiopathic dilated cardiomyopathy – the role of intra-operative echocardiography. Eur J Cardio-thorac Surg 2000; 17:239–245.
Bolling SF, Pagani FD, Deeb GM, Bach DS. Intermediate-term outcome of mitral reconstruction in cardiomyopathy. J Thorac Cardiovasc Surg 1998; 115:381–386. discussion 387–388.
Braun J, Bax JJ, Versteegh MI, Voigt PG, Holman ER, Klautz RJ, Boersma E, Dion RA. Preoperative left ventricular dimensions predict reverse remodeling following restrictive mitral annuloplasty in ischemic mitral regurgitation. Eur J Cardiothorac Surg 2005; 27:847–853.
Tibayan FA, Rodriguez F, Langer F, Zasio MK, Bailey L, Liang D, Daughters GT, Ingels NB, Miller DC. Annular or subvalvular approach to chronic ischemic mitral regurgitation. J Thorac Cardiovasc Surg 2005; 129:1266–1275.
Calafiore AM, Gallina S, Di Mauro M, Gaeta F, Iaco AL, D'Alessandro S, Mazzei V, Di Giammarco G. Mitral valve procedure in dilated cardiomyopathy: repair or replacement. Ann Thorac Surg 2001; 71:1146–1152. discussion 1152–1153.
Menicanti L, Di Donato M, Frigiola A, Buckberg G, Santambrogio C, Ranucci M, Santo D. Ischemic mitral regurgitation: intraventricular papillary muscle imbrication without mitral ring during left ventricular restoration. J Thorac Cardiovasc Surg 2002; 123:1041–1050.
Tahta SA, Oury JH, Maxwell JM, Hiro SP, Duran CM. Outcome after mitral valve repair for functional ischemic mitral regurgitation. J Heart Valve Dis 2002; 11:11–18. discussion 18–19.(Fumikazu Nomura, Tadashi )