A previous study demonstrated that heart failure symptoms and a lower EF were associated with higher late mortality . Therefore, in patients with LV systolic dysfunction, including a decreased ejection fraction and increased LV dimension, the effects of MV repair might be compromised. In this study, our results showed that in patients with LV systolic dysfunction, the incidence of perioperative complications was low, and thirty-day mortality was comparable to that in previous studies and our early study . Previous studies have shown that the perioperative mortality rate of MV repair in degenerative MR varies from 0.2 to 1.2% [1, 6, 9, 10]. MV repair was associated with lower mortality than replacement in patients with or without LV dysfunction [11, 12]. These results demonstrated that MV repair could be safely performed in patients with LV systolic dysfunction, and should be preferred over replacement.
Regarding mid- and long-term outcomes, the 8-year overall survival rate was 96.9% in this study. Tirone David and colleagues showed in their study that the 10-year survival rate for degenerative MR after MV repair was 85.6% . In in a study conducted by Coutinho et al., the 10-year survival rate for patients with preserved LV function was 89.7% . In another study, Enriquez-Sarano demonstrated that in patients with heart failure symptoms, an EF < 60% and LV end-systolic dimension> 40 mm, the 10-year survival rate was only 64% . Our results suggested that survival after MV repair in isolated degenerative MR patients with LV systolic dysfunction might not be severely compromised. In a previous study, Noack and colleagues evaluated isolated mitral valve repair in patients with reduced left ventricular ejection fraction. They found that the 5-year survival rate were 81.2, 75.2 and 58% in patients with EFs of 40–49%, 30–39% and < 30%, respectively. Considering that these patients experienced severe HF with a poor prognosis and quality of life, this result was acceptable . Current opinions [6, 14] and guidelines for valve diseases recommend that early surgical intervention is reasonable for severe degenerative MR in asymptomatic patients with preserved LV systolic function, and that these methods could improve outcomes [2,3,4]. However, patients with LV systolic dysfunction are not uncommon in real world practice. For these patients, “salvage” surgical intervention is still safe, helpful and necessary to prevent further myocardial damage and adverse events.
In this study, the incidence of recurrent MR for patients with LV systolic dysfunction was relatively higher than that in other studies. An early study  suggested that the incidence of recurrent MR after MV repair in degenerative disease was high (28.9% at 7 years). However, the latest studies [1, 16] suggested that the durability of MV repair for degenerative MR was excellent, at approximately 10% at 10 years. Generally, complex valve lesions (anterior lesion, Barlow disease, etc.) and inappropriate repair techniques were considered to be associated with increased risk of recurrent MR [9, 16, 17]. We also found in our study that anterior leaflet prolapse and intraoperative residual mild MR were independent predictive factors for recurrent MR; however, in previous studies, patients with preserved LV systolic function constituted most of the patient cohorts. In our previous study , we found that recurrent MR was only 3% at 8-year during follow up for those who received early surgical intervention before the onset of guideline-based indications. Therefore, preoperative LV systolic dysfunction might be associated with recurrent MR. A dilated left ventricle with LV systolic dysfunction could lead to annular enlargement and apically displaced leaflets, which cause secondary MR. Therefore, persistent LV systolic dysfunction might be a potential cause of recurrent MR. On the other hand, residual mild MR was not only a predictive factor for recurrent MR but was also associated with a higher risk of all-cause mortality. Interestingly, the incidence of recurrent MR was significantly higher in the deteriorated LV systolic function group than in the improved LV systolic function group. Although it was difficult to determine which factor initiated the process, progressive MR and LV systolic function could cause a perpetual cycle and lead to poor prognosis. This highlighted the necessity to avoid intraoperative residual MR, especially in patients who already developed LV dysfunction.
Our study found that deteriorated LV systolic function occurred in approximately 38% of patients. Previous studies have demonstrated that LV systolic dysfunction after MV repair is not uncommon, even in patients with preserved preoperative LV systolic function [18,19,20]. More importantly, early postoperative LV systolic dysfunction might be persistent and associated with poor long-term outcomes [18, 20]. In patients with an abnormal EF and enlarged LV dimensions, abnormal myocardial contractile function existed for a significant period. Although abnormal hemodynamics could be corrected by repair operations, LV systolic dysfunction might not be improved due to its prolonged disease stage. Therefore, in patients with preoperative LV systolic dysfunction, it is more important to identify the potential predictors for deteriorated LV systolic function. In this study, an age > 50 years, EF ≤ 52% and LV end-systolic dimension≥45 mm were identified as independent risk factors by ROC analysis and a logistic regression model for deteriorated LV systolic function during follow-up. Therefore, MV repair should not be delayed in these patients in order to reverse LV systolic dysfunction. Nevertheless, the incidence of recurrent MR and deteriorated LV function during follow-up was relatively high for patients with preoperative LV systolic function, therefore close follow-up was necessary in these patients.
Our study found that more severe heart failure symptoms and preoperative atrial fibrillation were associated with deteriorated LV systolic function, although they were not independent risk factors in multivariate analysis. Several previous studies [19, 21] have analyzed the determinants of LV systolic dysfunction after MV repair and also found that preoperative atrial fibrillation and pulmonary hypertension were predictive factors for LV systolic dysfunction as well. Atrial fibrillation and pulmonary hypertension are both signs of the severity of MR and predict a poor prognosis . Therefore, closer follow-up was necessary for patients who presented with a combination of LV systolic dysfunction, severe heart failure function and atrial fibrillation.
In a previous study , Imasaka and colleagues suggested that chordal replacement might be associated with better postoperative LV function than leaflet resection in the repair of posterior leaflet prolapse. However, in other studies [19,20,21], the factors of lesion segment and repair technique were not observed to be related to postoperative LV systolic dysfunction. Our results also suggested that the repair techniques were similar between the improved and deteriorated LV systolic function groups. Nevertheless, due to the potential relationship between recurrent MR and deteriorated LV systolic function, intraoperative residual mild MR should be avoided and managed carefully. In addition, close follow-up and postoperative echocardiography examinations are necessary for patients with LV systolic dysfunction. In the setting of persistent or deteriorated LV systolic function, the administration of standard anti-heart failure treatment is reasonable.
The present study was observational and retrospective, with the associated biases. Our single center’s experience might not apply to other institutions. Additionally, as a large tertiary hospital, we treat patients that come from all areas of the country. Therefore, the follow-up rate was negatively affected by the poor compliance of some patients from remote areas. Hence, approximately 25% of the follow-up echocardiographic examinations were performed at other institutions. Because we could not confirm every echocardiographic report generated at other institutions, some recurrent cases might have been missed detection. To maintain consistency between preoperative and follow-up echocardiography studies, the analysis of follow-up echocardiography profiles was only conducted for patients who underwent the examinations at our institution. The results might be affected by the sample selection. In addition, the mean follow-up time was relatively short in the present study. Further follow-up is needed to evaluate repair durability and LV systolic function in these patients.