Functional mitral regurgitation (MR) is common in patients with heart failure and left ventricular (LV) dysfunction. MitraClip (MC) is a novel therapeutic option for patients with high-risk MR. Similar to LV dysfunction, right ventricular dysfunction (RVD) is an important predictor of patients with heart failure. We aimed to clarify the effect of RVD on outcomes of functional MR and LV dysfunction after MC implantation. We examined 117 patients with severe functional MR and reduced LV ejection fraction (≤40%) treated with MC. RVD was defined as tricuspid annular plane systolic excursion <15 mm and was observed in 41 patients (35%). Mean age and gender were similar between patients with and without RVD. Atrial fibrillation was more common in patients with RVD. MR grades at baseline and discharge and LV ejection fraction were not different between the groups. Six months after MC implantation, responders to the N-terminal pro-B-type natriuretic peptide were less common in patients with RVD than those without (29% vs 65%, p = 0.005). Kaplan–Meier curves showed that survival rates of patients with RVD were significantly lower than those without (36.2% vs 69.6%, p = 0.008). After adjusting for covariates, RVD was still associated with all-cause mortality (hazard ratio 1.975, p = 0.042). The present study’s results suggest that RVD is associated with worse survival of functional MR and LV dysfunction in patients undergoing MC in association with no response to N-terminal pro-B-type natriuretic peptide. The indication for MC should be carefully considered in functional MR patients with RVD.
Functional mitral regurgitation (MR) is commonly observed in patients with left ventricular (LV) dysfunction and heart failure (HF). Mitral valve surgery is a standard treatment for severe MR. However, the clinical benefit of mitral valve surgery for patients with functional MR and LV dysfunction has not yet been established ; therefore, mitral valve surgery is frequently hesitated in these patients. Percutaneous edge-to-edge mitral valve repair using MitraClip (MC) is a novel therapeutic option for MR even in patients with a high surgical risk. MC is considered an attractive therapeutic option for patients with high-risk functional MR with LV dysfunction and advanced HF because of its superior safety. Similar to LV dysfunction, right ventricular dysfunction (RVD) is closely associated with the prognosis of patients with HF. However, the association between preprocedural RVD and the prognosis of patients with functional MR undergoing MC remains unclear. In the present study, we sought to clarify the effect of RVD on the outcomes of patients with functional MR treated with MC.
Methods
We enrolled consecutive patients with MR who underwent percutaneous edge-to-edge mitral valve repair using MC at the Heart Center Brandenburg from March 2009. All patients had a European System for Cardiac Operative Risk Evaluation >20% or other severe co-morbidities, suggesting that they had extremely high surgical risks, and they were evaluated by a multidisciplinary team. All patients had symptomatic severe (functional) MR grade >2, despite optimal medical treatment. Experienced investigators performed transthoracic and transesophageal echocardiography using commercially available ultrasound diagnostic systems (Vivid 7 and Vivid E9; GE Medical Systems, Milwaukee, Wisconsin; and Philips IE 33; Royal Philips Electronics, Amsterdam, The Netherlands). MR at baseline was graded according to the American Society of Echocardiography guidelines. After the procedure, MR grade was assessed by the technique reported by Foster et al. We did not consider MC therapy for patients who had severe clinical co-morbidities such as end-stage cancer or other severe diseases with a very unfavorable prognosis and those whose morphology of the mitral valve was technically impossible or unlikely beyond the classic Endovascular Valve Edge-to-Edge Repair Study criteria. We screened 255 patients for this study, and we excluded those with unsuccessful clip deployment (n = 6), degenerative MR (n = 85) or an unknown etiology (n = 2), LV ejection fraction (EF, >40%; n = 37) or a lack of LVEF data (n = 7), and lack of preprocedural tricuspid annular plane systolic excursion (TAPSE) data (n = 1). Finally, we analyzed 117 patients in this study. The median follow-up period was 707 ± 590 days. No patient was referred for heart transplantation. The ethical committee of our institution approved the protocols of this study. All patients were informed about the specific risks and alternative treatments, and they gave informed consent. The study was performed in accordance with the Declaration of Helsinki.
We defined LV dysfunction as LVEF ≤40% and RVD as TAPSE <15 mm. The estimated glomerular filtration rate was calculated using the Modification of Diet in Renal Disease equation. Chronic kidney disease was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m 2 . Responders to the N-terminal pro-B-type natriuretic peptide (NT-pro BNP) were defined as patients whose NP-pro BNP levels decreased by >30% according to previous studies.
We performed the percutaneous edge-to-edge mitral valve repair procedure using a 24Fr MC device (CDS01 or CDS02; Abbott Vascular, Santa Clara, California) under general anesthesia with the use of fluoroscopic and transesophageal echocardiographic guidance, according to previous studies.
Categorical and consecutive data regarding patients’ background are presented as numbers (%) and means ± SDs, respectively. The chi-square test was used to compare data between groups, and the unpaired t test was used to compare consecutive variables. We performed the paired t test to analyze changes in the parameters (baseline and 6 months after MC implantation). The long-term survival rate was estimated using Kaplan–Meier curves, and the log-rank test was used to assess the significance of differences between patients with and without RVD. We conducted univariate and multivariable Cox regression analyses to assess the effect of RVD on all-cause mortality after MC therapy. In multivariable Cox regression analysis, the effect of RVD was adjusted by age ≥75 years, New York Heart Association (NYHA) class IV, NT-pro BNP level >5,000 pg/ml, the presence of atrial fibrillation (AF), and a history of coronary artery bypass graft (stepwise method). A probability value of <0.05 was considered to indicate a statistically significant difference. We performed statistical analyses by using SPSS, version 19.0, software (SPSS Inc., Chicago, Illinois).
Results
Table 1 lists the study patients’ characteristics. RVD was observed in 41 patients (35%). Gender and the mean age were similar between patients with and without RVD. More than 90% of the study patients had NYHA classes III or IV, and the preprocedural NYHA class was not different between the groups. Approximately, half the study patients had NT-pro BNP level >5,000 pg/ml at baseline, and the preprocedural NT-pro BNP level was similar between patients with and without RVD. AF was more frequently observed in patients with RVD than in those without RVD (68% vs 38%, p = 0.003). A history of coronary artery bypass graft tended to be more common in patients with RVD than in those without RVD (34% vs 18%, p = 0.057).
