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ORIGINAL ARTICLE
Year : 2023 | Volume
: 24
| Issue : 4 | Page : 179-187
Transcatheter mitral valve repair with Mitraclip®: A nationwide experience
Shabib Abdulah Al-Asmi1, Rasha Kaddoura2, Mohammed Salah Abdelghani1, Ashraf Ahmed3, Cheik Abdoul Maaly4, Hakam Alzaeem4, Nazar Mohammed5, Mohanad Shehadeh1, Fahad Abdullah Al-Kindi5, Awad Al-Qahtani5, Mohammed Al-Hijji5
1 Department of Adult Cardiology, Heart Hospital, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
2 Department of Pharmacy, Heart Hospital, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
3 Department of Internal Medicine, Heart Hospital, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
4 Department of Non-Invasive Cardiology, Heart Hospital, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
5 Department of Interventional Cardiology, Heart Hospital, Hamad General Hospital, Hamad Medical Corporation, Doha, Qatar
Correspondence Address:
Dr. Mohammed Al-Hijji
Department of Interventional Cardiology, Heart Hospital, Hamad Medical Corporation, P. O. Box 3050, Doha
Qatar
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/heartviews.heartviews_90_23
Abstract
Background: Transcatheter mitral valve repair (TMVr), using MitraClip®, is a safe and effective procedure for severe mitral valve regurgitation (MR). However, the therapeutic results of MitraClip® in Qatar remain to be elucidated. A total of 25 patients (mean age 60 ± 14.5 years, 64% males) with symptomatic severe MR and prohibitive surgical risks were enrolled in this study. The procedural success rate was 92% to achieve mild residual MR. There was no periprocedural death. All patients experienced significant improvement in heart failure symptoms and MR grade postprocedure with sustained improvement over 1-year follow-up.
Conclusion: The TMVr procedure using the MitraClip® device was safe and resulted in meaningful and sustained functional status and echocardiographic parameter improvement.
Keywords: Edge-to-edge repair, mitral regurgitation, mitral valve, percutaneous valve repair
Introduction 
Valvular heart diseases represent a significant public health concern. With an overall prevalence of 2% in the general population, mitral valve regurgitation (MR) stands as the second-most prevalent valvular disease,[1] surpassed only by aortic valve disease.[2]
The etiology of MR can broadly be categorized as primary (also termed organic or degenerative) or secondary (also termed functional). MR carries a substantial morbidity and mortality burden regardless of the underlying cause or type of lesion.[3] Despite the absence of randomized trials, surgical mitral valve repair has long been considered the standard treatment approach for severe primary MR. This was supported by studies that have shown high success rates, infrequent instances of recurrence, improved symptoms, and the re-establishment of anticipated age- and sex-matched survival patterns.[4] In contrast, the prognosis of patients with severe secondary MR has not been significantly improved by mitral valve repair or replacement surgery; trials failed to prove benefit from the surgical approach. Instead, the primary treatment approaches for most patients involved guideline-directed medical therapy for heart failure and cardiac resynchronization therapy.[2],[4] Nearly half (49%) of patients diagnosed with severe MR were denied surgery. Among the factors associated with the decision to decline surgery was having grade 3+ MR (odds ratio: 2.23, 95% confidence interval: 1.28–3.29; P = 0.005).[5] However, approximately 50% of patients with severe MR who receive medical therapy usually die within 5 years and a significant proportion of them require hospitalization due to heart failure.[6]
Transcatheter mitral valve repair (TMVr) using the MitraClip® (Abbott Vascular, Santa Clara, California, USA) device has gained important attention as an alternative therapeutic option for MR patients who are at high risk for mitral valve surgery.[3] From 2008 onward, there has been a notable rise in the global utilization of TMVr procedures.[7] Multiple randomized trials have confirmed that TMVr using the MitraClip® device is the preferred treatment for selected patients.[4] The Endovascular Valve Edge-to-Edge Repair trials confirmed the feasibility, safety, and durability of the TMVr on the short- and long-term follow-up when compared to the surgical approach. However, primary MR was the predominant etiology in the studied population.[8],[9],[10],[11]
The Percutaneous Repair with the MitraClip Device for Severe Functional/Secondary Mitral Regurgitation (MITRA-FR)[12] and Cardiovascular Outcomes Assessment of the MitraClip Percutaneous Therapy for Heart Failure Patients with Functional Mitral Regurgitation (COAPT)[13] trials compared the effectiveness of the MitraClip® device with medical therapy. While the MITRA-FR trial did not improve the composite of death or unplanned heart failure hospitalization at 1-year follow-up,[12] the COAPT trial reported a significant reduction in death and hospitalization for heart failure.[13] In addition, the 3- and 5-year follow-ups of the COAPT trials confirmed the safety and efficacy of TMVr compared to medical therapy.[14],[15] Although the findings were inconsistent, the COAPT trial is widely recognized to have demonstrated the superiority of TMVr over medical therapy alone in treating patients with severe symptomatic secondary MR. Since its initial implementation, over 100,000 cases have been performed globally.[16]
Herein, we aimed to report the initial TMVr experience using the MitraClip® device in Qatar to demonstrate safety and efficacy in our patient population.
Methods Study design, setting, and population
The research question was addressed through a retrospective descriptive study that included all patients who underwent TMVr procedure using the MitraClip® device between September 1, 2019, and April 1, 2023. The study was conducted at the Heart Hospital, the only specialized tertiary cardiology center in Qatar, under the umbrella of Hamad Medical Corporation (HMC). The study was approved by the Institutional Review Board of HMC's Medical Research Center, and a waiver of informed consent was granted due to the retrospective design of the study. The study was conducted in full conformance with the principles of the Declaration of Helsinki, Good Clinical Practice, and within the laws and regulations of the Ministry of Public Health in Qatar.
Study procedures and definitions
A retrospective registry of patients who underwent TMVr procedure in the specified period was generated. A cross-sectional review of patient medical records was performed. The relevant prespecified data were collected, including demographics, cardiac history, comorbidities, medications, relevant hemodynamics, echocardiographic parameters, mitral valve characteristics, as well as procedural and clinical outcomes. Procedural success was generally defined as MR grade ≤2+ without associated complications. Clinical outcomes included death, hospital readmission for heart failure, and the need for surgery. Hemodynamics and echocardiographic outcomes included left ventricular dimensions, left ventricular ejection fraction, left atrial volume index, effective regurgitant orifice area, mean left atrial pressure, and left atrial v-wave. Data were collected at baseline, hospital discharge, and longer follow-up (30-day and 1-year).
Transcatheter mitral valve repair at heart hospital (Doha, Qatar)
The procedure was performed using regular and wider arm clips. The choice of the clip was dependent on the pathology of MR and the anatomy of the mitral valve. Access was obtained in the right femoral vein for the right heart catheterization and MitraClip® device deployment. Baseline mean left atrial pressure and v-wave pressure were measured in all cases. Then, the transseptal puncture was obtained using transesophageal echocardiography to achieve adequate height above the mitral valve. TMVr was successful if echocardiographic-derived valve regurgitation reduction by >50% from baseline was achieved with final post-TMVr MR grade <2+.
Statistical analysis
Data were managed using Excel and IBM SPSS Statistics (Version 20.0.1.0 (171), IBM Corporation 2023, Armonk, New York, USA) programs. Continuous variables were presented as mean (standard deviation, SD) or median (interquartile range). Categorical variables were expressed as frequencies and percentages. Inferential statistics using paired-Samples t-test for variables pre- and postprocedure or one-way ANOVA were performed for repeated echocardiographic continuous measurements over three- or four-time points at baseline (i.e., preprocedure) and follow-up periods (i.e., postprocedure and longer follow-up). The priori alpha level was set at 0.05.
Results Patients baseline characteristics
Twenty-five patients underwent TMVr procedure during the study period with a mean age of 60 ± 14.5 years. Of them, 16 (64%) patients were males with a mean Society of Thoracic Surgery risk score of 1.50 (0.03–2.74) and 2.32 (0.03–4.30) for mitral valve surgical repair or replacement, respectively. More than half of the patients were hypertensive and diabetics (56%). The majority of the patients (80%) had cardiomyopathy and was on guideline-directed medical therapy. Patient baseline characteristics are displayed in [Table 1]. Within 2 weeks of hospital admission, 76% of patients were in New York Heart Association (NYHA) class III or IV. Functional MR accounted for 76% of MR etiology, with 47% of an ischemic phenotype. Almost all the patients (96%) had severe MR grades (i.e., MR 4+) [Table 2]. Preprocedural echocardiographic parameters are shown in [Table 3].
Procedure characteristics and outcomes
Twenty (80%) patients underwent elective TMVr procedure through the right femoral site under general anesthesia. Three (12%) patients underwent TMVr in the setting of cardiogenic shock, requiring vasoactive agents during the procedure. A mean of 1.6 ± 0.6 clips were deployed, with one clip implanted in 13 (52%) patients, two clips in 10 (40%) patients, and three clips in two (8%) patients. Other characteristics are presented in [Table 3]. The acute procedural success rate was 92%. The preprocedure mean left atrial pressure in the right heart catheterization was 25.5 ± 9.9 mmHg with a mean left atrial v-pressure of 40.7 ± 19.6 mmHg. There was a significant reduction in the mean left atrial pressure to 17.2 ± 5.7 and v-wave pressure to 22.8 ± 10.3 mmHg [Figure 1].
Figure 1: Mean left atrial pressure (LAP) and LAP v-wave at baseline and follow-upEchocardiographic data at admission and follow-up
The effective regurgitant orifice area was significantly reduced from 0.45 cm ± 0.11 cm to 0.14 cm ± 0.06 cm (P < 0.001) and maintained over 30-day and 1-year follow-up periods. Similarly, the mean gradient significantly improved from 1.2 ± 0.46-3.4 ± 1.3 mmHg postprocedure (P < 0.001) and maintained over 30 days (P = 0.001) and 1-year follow-up (P = 0.002). Significant ongoing remodeling and improvement in left atrial and left ventricular size and dimensions started 30 days postprocedure and continued at 1-year follow-up [Figure 2]. Echocardiograms obtained intra-procedure, postposture, at 30-day, and 1-year follow-up showed marked sustained reduction in MR grade severity [Figure 3]A.
Figure 2: Left ventricular function at baseline and follow-up. LAVI: Left atrial volume index, LVEF: Left ventricular ejection fraction, LVIDD: Left ventricular internal dimension in diastole, LVISD: Left ventricular internal dimension at systole
Figure 3: (A) Mitral valve regurgitation grade at baseline and follow-up. (B) NYHA class at baseline and follow-up. MR: Mitral valve regurgitation, NYHA: New York Heart AssociationClinical outcomes in-hospital and at follow-up
Heart failure symptoms have markedly improved after the procedure with 91% of patients in NYHA class II at 1-year follow-up [Figure 3]B. More than 90% of patients were on beta-blocker therapy and 70%–80% were on either angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or angiotensin receptor and neprilysin inhibitors [Figure 4]. Overall, there were no adverse clinical outcomes either in the hospital, upon discharge, or at 30-day follow-up. At 1-year follow-up, five patients were readmitted for heart failure. Another patient had severe residual MR with recurrent and underwent mitral valve replacement surgery. One patient underwent left ventricular assist device implantation for advanced cardiomyopathy. Only one patient died 6 months after the procedure and was frequently hospitalized for heart failure due to advanced-stage ischemic cardiomyopathy.
Figure 4: Medications at baseline and follow-up. ACEI: Angiotensin-converting enzyme inhibitors, ARB: Angiotensin receptor blockers, ARNI: Angiotensin receptor and neprilysin inhibitors, FU: Follow-up, MRA: Mineralocorticoid receptor antagonists, SGLT2i: Sodium-glucose co-transporter-2 inhibitors Discussion This is the first report presenting the initial experience on the safety and efficacy of the TMVr procedure using the MitraClip® device in Qatar. The report highlights the safety of the procedure without significant in-hospital or 30-day adverse events and with an acute procedural success rate of 92% in high-risk populations with either degenerative or functional MR etiology. There were a few urgent procedures that were performed on patients with acute cardiogenic shock.[17] One patient had a single leaflet detachment that was successfully managed with stabilization using additional clips.[18] Only one patient required mitral valve surgery. Overall, our study demonstrated early and sustained improvement in the left ventricular hemodynamics and dimensions, and MR grade post TMVr up to 1-year follow-up with low morbidity and mortality.
Other Asian MitraClip® initial experience has been published from Japan and Taiwan.[19],[20] In comparison with the population in Qatar, Taiwanese and Japanese were one and two decades older, respectively, with higher rates of hypertension. Female gender, functional MR etiology, and diabetes were more frequent among the population in Qatar. Both Asian studies (Japanese and Taiwanese) did not report outcomes at 1-year follow-up [Table 4].[19],[20] In addition, the Japanese study (n = 30) reported the outcomes according to MR etiology. The authors found that patients with degenerative MR were older (by 5.5 years), had more female proportion, and had higher diabetes incidence than those with functional MR, who tend to have more severe renal impairment and a history of cardiac surgery. However, both subgroups did not differ in terms of safety and efficacy outcomes.[19] Similarly, El-Shurafa et al. reported TMVr procedure outcomes according to MR etiology in 111 patients. Patients with degenerative MR (n = 23; 21%) were older by 11 years, while patients with functional MR (n = 88; 79%) experienced more myocardial infarction events (65% vs. 22%, P = 0.001). Safety and efficacy outcomes did not differ between the subgroups.[21]
A report from The MitraClip in the Asia-Pacific Registry has also concluded that the MitraClip® approach was safe and effective in both MT etiologies. Despite observing a considerably greater reduction in left ventricular volumes in degenerative MR, patients in both groups showed improvements in functional class.[22] Given that the real-life data on TMVr from the observational studies showed variability in patient selection, and procedural and clinical outcomes in comparison with those reported in randomized trials,[1] it would be reasonable to further compare our study results with those reported in the international registries [Table 4].[23],[24],[25],[26],[27]
Patients in the international registries were older, with a higher incidence of hypertension and a lower incidence of diabetes. Degenerative MR etiology was diagnosed in 86% of patients in the registry.[23] Overall, the acute procedural success rate was more than 90%. The rates of 1-year death and hospitalization for heart failure were 12%–26% and 20%–31%, respectively.
Numerous technological advancements have been made since the first-generation MitraClip® device was approved for commercial use in Europe (2008) and the United States (2018). Then, the release of the second (NT) and third (NTR and XTR) generations of the device followed in 2016 and 2018, respectively. The efficacy and safety of the third-generation devices have been confirmed in the Global EXPAND postmarket study in patients with secondary MR. The MR reduction to grades ≤2+ and ≤1+ was maintained at 1-year follow-up in 98.5% and 93% of patients, respectively. MR grade reduction was similar between NTR and XTR, with fewer XTR clips being required to achieve the reduction.[28] The fourth-generation device was released in 2019 with wider clip arms (NTW and XTW), which results in independent grasping and improved clip deployment sequence.[28],[29],[30] In the prospective, single-arm EXPAND G4 study that enrolled 1141 patients with primary and secondary MR, the MitraClip® G4 system was safe and effective at 30-day follow-up. The MR was reduced considerably (≤2+ in 98% and ≤1+ in 91% of patients), heart failure symptoms were improved remarkably, and the quality of life was enhanced without frequent adverse events.[30] Our experience started with the third-generation Mitraclip device and then moved to 4th generation at a later stage.
Conclusion Our study has several limitations to be acknowledged. The main limitation is the retrospective nature of the design, which creates bias and confounding. The sample size was small, and the long-term follow-up was restricted to 1 year. These data reflect the initial experience with the MitraClip® device in Qatar and are consequently constrained by the learning curve of the individual operators. Although this is a single-center study with limited generalizability, the population in Qatar is quite heterogeneous, given the high number of expatriates proportion that live in it. In conclusion, the TMVr procedure using the MitraClip® device was safe and resulted in meaningful and sustained functional status and echocardiographic parameter improvement in our patient population.
Acknowledgment
We thank all the Heart Hospital and Cath lab staff for their immense efforts in taking care of our patients.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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