|Year : 2017 | Volume
| Issue : 1 | Page : 10-16
Management of moderate ischemic mitral regurgitation: revascularization alone versus revasularization and mitral valve repair
Mohamed K Abd El Naby1, Youssry Al-Saeed2, Ali H Taher3, Hany M El-Rakhawy1, Medhat N Riad Moussa3
1 Department of Cardiothoracic Surgery, Faculty of Medicine, Benha University, Benha, Egypt
2 Department of Cardiac Surgery, Faculty of Medicine, Benha University, Benha, Egypt
3 Department of Cardiac Surgery, National Heart Institute, Cairo, Egypt
|Date of Submission||10-Nov-2016|
|Date of Acceptance||28-Nov-2016|
|Date of Web Publication||24-May-2017|
Medhat N Riad Moussa
42 B Khesrou street, Helwan, Cairo, postal code 114214
Source of Support: None, Conflict of Interest: None
Ischemic mitral regurgitation (IMR) is a frequent condition post-myocardial infarction. Management of moderate myocardial infarction is still debatable, with adding mitral valve repair (MVR) to coronary artery bypass grafting (CABG) being questionable.
To compare echocardiographic and clinical outcome of moderate IMR treated by revascularization alone versus another group of patients treated by revascularization and MVR.
Patients and methods
Forty consecutive patients with ischemic heart disease with moderate IMR undergoing on-pump CABG are randomly selected. They were divided into two groups: group I (20) had CABG+MVR, group II (20) had only CABG; echocardiography was done postoperatively and after 6 months for both groups.
Our study revealed improvement in the grade of mitral regurgitation (MR) in both groups which was more evident and significant in group I than II with 11 (61%) of group I showing complete resolution of MR versus 0 patients in group II which was highly statistically significant (P=0.0001). Follow-up after 6 months, there were significant reduction in the New York Heart Association functional class as well as the mean grade of MR in group I versus group II, (P=0.004), with nine (50%) patients in group I against two (11%) patients in group II had complete resolution (P=0.004). We found also significant reduction in left ventricular dimensions and function.
MVR can be performed safely, concomitantly with coronary artery bypass grafting in patients who have moderate IMR.
Keywords: coronary artery bypass grafting+mitral valve repair, ischemic heart disease, ischemic mitral regurgitation, mitral valve repair, moderate ischemic mitral regurgitation
|How to cite this article:|
Abd El Naby MK, Al-Saeed Y, Taher AH, El-Rakhawy HM, Riad Moussa MN. Management of moderate ischemic mitral regurgitation: revascularization alone versus revasularization and mitral valve repair. Benha Med J 2017;34:10-6
|How to cite this URL:|
Abd El Naby MK, Al-Saeed Y, Taher AH, El-Rakhawy HM, Riad Moussa MN. Management of moderate ischemic mitral regurgitation: revascularization alone versus revasularization and mitral valve repair. Benha Med J [serial online] 2017 [cited 2017 Sep 19];34:10-6. Available from: http://www.bmfj.eg.net/text.asp?2017/34/1/10/206901
| Introduction|| |
Ischemic mitral regurgitation (IMR) is a common complication (∼20%) after myocardial infarction (MI), following more frequently an inferior MI (38%) rather than an anteroseptal one (10%) .
IMR is associated with diminished survival compared with non-IMR. Its increased risk is related to the grade of mitral regurgitation (MR) .
The management of moderate IMR (+2 and +3) is still debatable, as some studies have shown that uncorrected MR leads to increased postoperative morbidity and mortality, while others claim that mitral valve surgery may add to the operative risk when combined with revascularization .
| Patients and methods|| |
This is a prospective randomized study done at the Cardiothoracic Surgery Department, in National Heart Institute, as well as in Benha University Hospitals in Egypt, in the period between January 2014 and June 2014. Our materials and methods were approaved by the ethical committee of our local organization. The study was conducted on 40 consecutive patients with ischemic heart disease (IHD) undergoing coronary artery bypass grafting (CABG) with moderate IMR, and they are randomly selected. The patients were divided into two groups:
Group I: 20 patients with IHD and moderate IMR had on-pump CABG for revascularization and mitral valve repair (MVR).
Group II: 20 patients with IHD and moderate IMR had only on-pump CABG for revascularization.
Patients were eligible for enrollment in the study if they had referred for on-pump CABG and had moderate IMR measured by echocardiography at rest.
Moderate IMR was defined by the presence of at least two of three criteria recommended by the American Society of Echocardiography: an effective regurgitant orifice area of 0.2 to less than 0.4 cm 2, a vena contracta width of 3 to less than 7 mm, and a ratio of the MR jet area to the left atrial (LA) area of 20% to less than 40%.
Baseline characteristics of the study population are presented in [Table 1] (results).
|Table 1 Preoperative patient, clinical and echocardiographic characteristics of the two surgical groups (revascularization combined with mitral valve repair and revascularization alone)|
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Each patient signed an informed consent form.
Clinical study end point
The end point of the study was to evaluate the effect of adding MVR to CABG on the clinical status of patients measured based on New York Heart Association (NYHA) functional class and on postoperative reversal of left ventricular (LV) remodeling measured based on LV end-systolic diameter (ESD), LV end-diastolic diameter (EDD),and LV ejection fraction (EF) and also to assess the effect of adding MVR to CABG on postoperative residual MR of grade 2+ or less.
Echocardiography was performed early postoperatively and 6 months after surgery for all patients in both study groups. The severity of IMR was assessed by means of transthoracic echocardiography, M-mode, two-dimensional, and Doppler echocardiography. Different dimensions of the cardiac chambers were measured, as well as EF, regional wall motion abnormalities, evaluation of other valves, and the grade of MR.
All patients underwent conventional multivessel CABG through a full midline sternotomy on normothermic cardiopulmonary bypass under general anesthesia, and myocardial protection achieved using intermittent antegrade warm blood cardioplegia. In patients randomized to CABG plus MVR, the mitral valve was inspected to confirm the absence of any structural abnormalities. The type of repair is decided dedicated according to the surgeon’s discretion. All the cases had undersized ring annuloplasty using a rigid incomplete annuloplasty ring. The recommended ring was Carpentier–Edwards ring. Ring sizing was based on the size of the anterior leaflet or based on the intercommissural or intertrigonal distance, and the ring was downsized by two sizes when possible to correct for annular dilatation, However, two patients received additional Alfieri stitch as decided by the surgeon after finishing applying the ring. Surgical data are summarized in [Table 2] (Results). Postoperative ICU management was standardized for all patients.
Clinical and echocardiographic follow-up
All the patients were followed up at our outpatient clinic after 6 months by assessment of NYHA class and echocardiography performed by the same cardiologists. Follow-up was 100% complete.
Data were analyzed by Microsoft Office 2003 (excel) (Microsoft Compagny, Redmond-Washington, USA) and statistical package for the social science (SPSS), version 16. Parametric data were expressed as mean±SD, and nonparametric data were expressed as the number and percentage of the total, the mean and SD. Comparing the mean±SD of two groups was done using the paired Student’s t-test. Determining the extent to which a single observed series of proportions differs from a theoretical or expected distribution was done using the χ2 test. P value up to 0.05 is considered significant, P value up to 0.01 is considered highly significant.
| Results|| |
The preoperative demographics, clinical, and echocardiographic characteristics of the two surgical groups are shown in [Table 1] with the only significant variable being the LA dimension. Segmental wall motion abnormality with 25 (62.5%) patients had been posteroinferior, while only 12 (30%) had anterolateral wall motion abnormality (P<0.01). Segmental wall motion abnormality with 25 (62.5%) patients had been posteroinferior, while only 12 (30%) had anterolateral wall motion abnormality (P<0.01).
The operative time including total pump time and aortic cross clamp time was significantly higher in the repair group (P<0.01), while the mean number of grafts per patient was statistically higher in the revascularization-only group (P<0.05) as depicted in [Table 2].
Total period of mechanical ventilation and mean values of the total ICU stay in hours were statistically higher in group I; as regards postoperative complications, one patient had perioperative MI and severe deterioration in LV EF in immediate postoperative echocardiography. We had a total of three in-hospital mortality (<30 days), two (10%) patients in the repair group and one (5%) patient in the revascularization-only group; however, the difference was statistically insignificant ([Table 3]).
Immediate postoperative echocardiographic data
The postoperative echocardiographic data were collected from the surviving patients (18 out of 20 patients in group I and 19 out of 20 patients in group II), with improvement in the MR grade which was highly statistically significant in group I than II ([Table 3]).
Follow-up data at 6-month interval were collected from all surviving patients (18 out of 20 patients in group I and 19 out of 20 patients in group II), with the mean grade of MR which was significantly higher in revascularization-only group (P=0.004) ([Table 4]).
To evaluate the effect of each procedure we studied the course of variables’ change in each group over function of time; the reduction of LV EF and LV ESD was significant in both groups while the reduction EDD was highly significant in group I but was nonsignificant in group II, both LA dimension, mean grade of MR, and NYHA functional class decreased highly significant in both groups over time ([Table 5]).
|Table 5 Variable change over function of time: preoperative, postoperative and 6 months follow-up|
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We study the effect of improved EF by comparing patients who had significant improvement in EF with those who did not, in both study groups, then we found that in those patients who had improved EF in both groups there were highly significant improvement in all other variables including LV dimensions and grade of MR as well as the NYHA functional class, while in those without improvement in EF, all the variables were not improved significantly in both groups except in group I, where both MR grade and NYHA functional class improved significantly.
| Discussion|| |
IMR develops in ∼50% of patients post-MI, with in moderate degree occuring in more than 10% of patients; it is associated with poor outcome regardless of management .
While there is general consensus regarding management of mild and severe degree of IMR the optimal management for moderate (II and III) remains controversial. .
The opponents of CABG alone for the treatment of moderate IMR argue that revascularization may improve LV function, reducing the LV size, restoring the functional integrity of the subchordal mitral-valve apparatus, improving MR degree; however, combined with revascularization may add to the operative risk. In addition to poor long-term outcome , while advocators for adding mitral repair to CABG cite the adverse consequences of persistent MR, especially for patients with LV dysfunction, in whom mitral repair may prevent progressive adverse remodeling, improving cardiac function, reducing risk of heart failure . The optimal strategy for treatment of moderate IMR is not known .
According to the last edition (the 7th edition) of FEIGENBAUM’S Echocardiography , MR has been classified to mild class I, moderate class II and III, severe class IV; consequently, in our study we subclassify moderate IMR into two: categories II and III.
Therefore, we conducted this study to track the course of moderate IMR after CABG surgery alone and after combining surgery with MVR on the immediate and early outcome of IHD patients undergoing CABG.
Both study groups were homogeneous regarding the preoperative demographic data with no statistically significant differences as regards age, sex, risk factors for ischemic heart disease, history of previous MI, and the NYHA functional class.
Despite anginal pain being the main presenting symptoms with majority of patients, 29 (72.5%) had a positive history of previous MI, only one hypertensive female patient on full medical treatment had presented with recurrent attacks of acute pulmonary edema and dyspnea, giving a history of previous percutaneous transluminal coronary angiography to the right coronary artery with in-stent restenosis, although she had completely normal left anterior descending operation done for correction of the functional IMR and grafting of the right coronary artery, both high systolic blood pressure with dynamic nature of IMR might have contributed to the exacerbation of MR and consequently pulmonary edema .
Segmental wall motion abnormality (SWMA) in the form of dyskinesia or hypokinesia was a constant finding in all our patients, with most of them [25 (62.5%) patients] having undergone inferior/posterior SWMA wall versus only 12 (30%) of the patients having undergone anterior and/or lateral wall SWMA, in addition to three (7.5%) of the patients having had global hypokinesia.
This validates data that although anterior infarctions are common in IHD patients, the IMR is more common after a posteroinferior MI, as the posteromedia papillary muscle is more vulnerable to ischemia than the anterolateral one due to its single blood supply and due to direct involvement of important components of the mitral apparatus, the basal inferior LV wall adjacent to the posterior posteromedia and mitral annulus .
Our study revealed that operative time including total pump time and aortic cross clamp were more prolonged in group I than in group II with highly significant difference between both groups: P (<0.01); this could be attributed to the extra time needed for the mitral valve procedure in the first group. This is comparable with the results obtained by Goland et al.  and Harris et al. ; however, both studies showed higher mean times in both parameters than in ours due to the increased mean number of grafts in both studies than in ours.
Postoperative complications in the form of reopening, although higher in group I five (25%) versus three (15%) in group II, was statistically insignificant, which could be explained by the longer bypass time and aortic cross clamp in the combined group (group I) in addition to the obligatory cardiotomy needed for MVR.
In addition, there was no significant difference between the two groups as regards the mortality with in-hospital (30 days mortality rate) it was three patients, two (10%) in the repair group, and one (5%) patient in the revascularization-only group, with the difference being statistically insignificant. We had two intraoperative mortalities, one in each group, due to failure of weaning of cardiopulmonary bypass: the first in group I was a diabetic woman of 53 years with bad target vessels, and in group II the patient was a 76 year-old man with global hypokinesia and left main disease. Another one in group I died in ICU, he was 75 years old with delayed recovery and prolonged ventilation; he died of pneumonia leading to type II respiratory failure and septicemia. This was comparable with Tekumit et al.  and Kim et al. .
Our results have shown complete resolution of MR in 11 (61%) patients in group I versus none in group II with highly statistical difference in between. Some reduction in the severity of MR was noticed in seven (39%) patients in group I versus 13 (68%) patients in group II with no statistical difference in between and six (32%) patients in group II remained with the same grade of MR (grade II). However, these immediate changes in the grade of MR were not accompanied by similar changes in LA dimension, LV dimensions and function, and this was not an unexpected finding as reverse remodeling, if any, to occur needs longer time interval.
At 6 months follow-up, persistence reduction of mean of MR noticed and it was greater in group I (0.72) than in group II (1.63), and in comparison to baseline this reduction was higher in group I 68.52±38.30% versus only 34.17±45.39% in group II with highly statistical significant difference in between (P=0.004); in addition, nine (50%) patients of group I continue to be grade 0 versus two (10%); in group II newly developed grade 0 at this follow-up with highly significant statistical difference. But no statistical differences between both groups as regards the residual mitral or patients with progressed degree of MR.
Likewise, Goland et al.  in their study on 83 patients who had moderate IMR, found highly significant improvement in MR grade in their combined CABG+MVR patients, in comparison with their CABG-only patients within 12-month follow-up (P<0.0001).
Similarly, Kim et al.  showed significant reduction of grade of MR after combined revascularization and MVR than after revascularization alone in early (0–10 months) follow-up. However, they had a greater reduction in severity of MR in the combined group and less reduction in revascularization-only group than ours; (2.7±0.1) versus (0.2±0.1), respectively (P<0.001). This difference might be attributed to larger number of patients who had preoperative grade IV MR included in their study: 12% in combined group and 84% in revascularization-only group versus none in our study.
On the contrary, Wong et al.  in their study on 251 patients who had moderate IMR, showed greater mean residual of MR at follow-up, 2.6±0.8 in CABG-only group and 2.0±0.9 in the repair group. However, several points worth noting: first, they had a large number of patients with EF less than 40% (51% in CABG-only group and 40.9% in the repair group); second their study was retrospective with a follow-up period of up to 10 years.
The reduction in grade of severity of MR at 6 month follow-up is accompanied with reverse remodeling in LA and LV dimensions together with improvement in LV function in both groups, without statistically significant difference in between; this was similar to Goland et al.  and Tekumit et al. .
Although the mean NYHA functional class was significantly improved over time interval follow-up in both groups and the improvement was higher in group I (46.67±27.89%) than in group II (28.33±62.85%) and although one of the patients of group I maintained his preoperative (class II) functional class but none was in class III in that group, versus four in group II; of these, two maintained the same grade of their preoperative class, as they had preoperative reduced EF, showed no LV function improvement, and progression of MR severity at follow-up, The other two patients showed worsening of their functional class and deterioration of LV function at follow-up; one of them showed progression of MR severity, the other one had documented MI, and was admitted to our CCU during follow-up interval. This was comparable with Goland et al. ; however, they had 67% of patients in the repair group in NYHA class I or II versus 100% of patients in our corresponding group, while in CABG-only group they reported 87% of patients in NYHA class I or II, versus 79% in our study, with the trend toward higher improvement in NYHA functional class in CABG-only group in this study could be explained only by the larger percentage of patients in class III or IV included in their repair group (89%) versus only (71%) in CABG-only group at preoperative.As mentioned before, patients with ischemic cardiomyopathy and functional IMR represent a very heterogeneous population that differs in the extent of myocardial viability and function. To study the effect of repair independent of postoperative LV function, we further divided each group into two subgroups, first is the group of patients who showed postoperative LV functional improvement, and second is the group of patients who showed no LV functional improvement.
Our observations have shown that both subgroups that showed LV functional improvement also showed statistically significant reduction in ESD, EDD, grade of MR severity, and NYHA functional class at follow-up in comparison with preoperative baseline. This might be due to coronary artery revascularization which improved LV dysfunction and geometry, restoring valvular coaptation, improving MR, while those without functional improvement, showed non-statistically significant reduction in LV dimension in both groups. There was significant reduction in the grade of MR and NYHA functional in the repair only group, this was similar to Kang et al.  study. This finding led Flyn et al.  to suggest the importance of routine assessment myocardial viability preoperatively in IMR helping the decision of adding mitral repair to CABG in IMR.
| Conclusion|| |
MVR can be performed safely, concomitantly with CABG in patients who have moderate IMR (grades II and III), without affecting the immediate and early outcomes of these patients.
The combined procedure resulted in a greater decrease in severity of MR; moreover, in patients without functional recovery (EF), MVR showed some LV reverse remodeling and significant improvement of NYHA functional class and hence the quality of life.
Viability study should be done preoperatively, especially for patients in whom mitral valve was decided to be left alone to support or to alter the surgical decision.
In patients with poor LV function, there is a higher incidence of postoperative residual MR or even progression; hence, concomitant ring annuloplasty for the mitral valve would be a better surgical option.
The authors thank Dr Yasser George, MD, professor of cardiology in National Heart Institute for conducting the echocardiography study needed for the study cases, and his continuous support by providing many textbook references that were needed to accomplish this work.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]