Edge-to-edge surgical mitral valve repair in the era of MitraClip: what if the annuloplasty ring is missed?

Machine learning used for simulation of MitraClip intervention: A proof-of-concept study

Introduction: Severe mitral regurgitation (MR) is a mitral valve disease that can lead to lifethreatening complications. MitraClip (MC) therapy is a percutaneous solution for patients who cannot tolerate surgical solutions. In MC therapy, a clip is implanted in the heart to reduce MR. To achieve optimal MC therapy, the cardiologist needs to foresee the outcomes of different scenarios for MC implantation, including the location of the MC. Although finite element (FE) modeling can simulate the outcomes of different MC scenarios, it is not suitable for clinical usage because it requires several hours to complete.

Methods: In this paper, we used machine learning (ML) to predict the outcomes of MC therapy in less than 1 s. Two ML algorithms were used: XGBoost, which is a decision tree model, and a feed-forward deep learning (DL) model. The MC location, the geometrical attributes of the models and baseline stress and MR were the features of the ML models, and the predictions were performed for MR and maximum von Mises stress in the leaflets. The parameters of the ML models were determined to achieve the minimum errors obtained by applying the ML models on the validation set.

Results: The results for the test set (not used during training) showed relative agreement between ML predictions and ground truth FE predictions. The accuracy of the XGBoost models were better than DL models. Mean absolute percentage error (MAPE) for the XGBoost predictions were 0.115 and 0.231, and the MAPE for DL predictions were 0.154 and 0.310, for MR and stress, respectively.

Discussion: The ML models reduced the FE runtime from 6 hours (on average) to less than 1 s. The accuracy of ML models can be increased by increasing the dataset size. The results of this study have important implications for improving the outcomes of MC therapy by providing information about the outcomes of MC implantation in real-time.

Transcatheter edge-to-edge mitral valve repair in patients with mitral annulus calcification

BACKGROUND

MAC is commonly found in patients affected with MR, and it is associated with high morbidity, mortality and worse cardiac surgical outcomes. Transcatheter edge-to-edge repair could be an alternative treatment, although there is little evidence in this population.

AIMS

The aim of this study was to analyse the safety, efficacy and durability of MitraClip implantation in patients affected with mitral regurgitation (MR) and mitral annulus calcification (MAC).

METHODS

We analysed the outcomes of 61 suitable patients affected with severe MR and moderate or severe MAC (the "MAC" group) and 791 patients with no or mild MAC (the "NoMAC" group) treated with the MitraClip device.

RESULTS

Procedural success was similar (91.8% vs 95.1%, p=0.268, in MAC and NoMAC, respectively), with a very low rate of complications. At one-year follow-up, 90.6% of MAC and 79.5% of NoMAC patients had MR grade ≤2 (p=0.129), 80% in both groups remained in NYHA Functional Class ≤II, and a significant reduction in cardiac readmissions was observed (65% vs 78% in MAC vs NoMAC, p=0.145). One-year mortality tended to be higher in MAC patients (19.7% vs 11.3%, p=0.050), with no difference in cardiovascular mortality (15.3% vs 9.2%, p=0.129).

CONCLUSIONS

MitraClip use in selected patients with moderate or severe MAC is safe, feasible and achieves good clinical and echocardiographic results at one-year follow-up.

The impact of transcatheter edge-to-edge repair on mitral valve annular geometry

PURPOSE OF REVIEW

Mitral valve transcatheter edge-to-edge repair (TEER) is becoming increasingly common to treat severe mitral regurgitation. However, the lack of concomitant annuloplasty raises concerns regarding its durability. As a result, there is an emerging body of literature evaluating the impacts of TEER on mitral annular geometry. In this review, we summarize the most recent literature evaluating the impacts of TEER on annular geometry in the acute, intermediate and long-term. We also review the relationship between changes in annular geometry and clinical endpoints.

RECENT FINDINGS

Current evidence suggests that TEER acutely induces favourable changes in mitral annular size and shape, which may persist for at least up to 1 year. Few studies suggest that TEER-induced annular remodelling is associated with positive clinical outcomes.

SUMMARY

The current body of literature is sparse and limited to primarily small case series. Data from the surgical literature suggest that ringless edge-to-edge repair is associated with eventual failure. Unfortunately, few studies evaluate TEER-induced annular changes beyond the acute postprocedural phase. Future research needs to focus on and evaluate the significance of TEER-induced changes in annular dimensions in the long-term.

Mitral Valve Atlas for Artificial Intelligence Predictions of MitraClip Intervention Outcomes

Severe mitral regurgitation (MR) is a cardiac disease that can lead to fatal consequences. MitraClip (MC) intervention is a percutaneous procedure whereby the mitral valve (MV) leaflets are connected along the edge using MCs. The outcomes of the MC intervention are not known in advance, i.e., the outcomes are quite variable. Artificial intelligence (AI) can be used to guide the cardiologist in selecting optimal MC scenarios. In this study, we describe an atlas of shapes as well as different scenarios for MC implantation for such an AI analysis. We generated the MV geometrical data from three different sources. First, the patients' 3-dimensional echo images were used. The pixel data from six key points were obtained from three views of the echo images. Using PyGem, an open-source morphing library in Python, these coordinates were used to create the geometry by morphing a template geometry. Second, the dimensions of the MV, from the literature were used to create data. Third, we used machine learning methods, principal component analysis, and generative adversarial networks to generate more shapes. We used the finite element (FE) software ABAQUS to simulate smoothed particle hydrodynamics in different scenarios for MC intervention. The MR and stresses in the leaflets were post-processed. Our physics-based FE models simulated the outcomes of MC intervention for different scenarios. The MR and stresses in the leaflets were computed by the FE models for a single clip at different locations as well as two and three clips. Results from FE simulations showed that the location and number of MCs affect subsequent residual MR, and that leaflet stresses do not follow a simple pattern. Furthermore, FE models need several hours to provide the results, and they are not applicable for clinical usage where the predicted outcomes of MC therapy are needed in real-time. In this study, we generated the required dataset for the AI models which can provide the results in a matter of seconds.

Current status of the treatment of degenerative mitral valve regurgitation

Degenerative mitral valve disease (myxomatous degeneration or fibroelastic deficiency) is the most common indication for surgical referral to treat mitral regurgitation. Mitral valve repair is the procedure of choice whenever feasible and when the results are expected to be durable. Posterior leaflet prolapse is the commonest lesion, found in up to two-thirds of patients. It is the easiest to repair, particularly when limited to one segment. In these cases, rates of repairability and procedural success approach 100%, and there is now ample evidence that the immediate and long-term results are better than those of valve replacement. Notably, minimally invasive valvular procedures, surgical or interventional, have attracted increasing interest in the last decade. When performed by experienced groups, mitral valve repair is unrivaled irrespective of the severity of lesions, from simple to complex, which leaflets are involved, and the type of degenerative involvement (myxomatous or fibroelastic). Its results should be viewed as the benchmark for other present and future technologies. By contrast, percutaneous mitral valve repair is still in its infancy and its results so far fall short of those of surgical repair. Nevertheless, continued investment in transcatheter procedures is of great importance to enable development and improved accessibility, particularly for patients who are considered unsuitable for surgery. In this review, we analyze the current status of management of degenerative mitral valve disease, discussing mitral valve anatomy and pathology, indications for intervention, and current surgical and transcatheter mitral valve procedures and results.

Mitral Regurgitation in Patients With Coexisting Chronic Aortic Regurgitation: An Evidence-Based Narrative Review

Chronic aortic regurgitation (AR) frequently leads to significant downstream changes to the left ventricle and pulmonary vasculature; these structural and physiologic changes result in lower- than expected patient survival. Progressive, uncorrected AR can lead to left ventricle dilation and subsequent mitral valve leaflet tethering, as well as mitral annular dilation, resulting in secondary mitral regurgitation (MR) in up to 45% of patients. Surgical aortic valve replacement (AVR) improves secondary MR in most patients, but survival is significantly lower in those patients who do not show improvement in MR after AVR. Thus, there is considerable debate on whether the mitral valve should be intervened upon at the time of the AVR. In this review, the authors address the long-term outlook for patients with chronic AR and concurrent MR. The authors also review the available evidence on concomitant mitral valve surgery in patients undergoing AVR for AR. Lastly, this narrative review examines the recent advances in transcatheter mitral valve repair and replacement, and explores the potential role of transcatheter mitral therapies in patients with secondary MR due to AR.

Aortic valve replacement in patients with a left ventricular ejection fraction ≤35% performed via a minimally invasive right thoracotomy

BACKGROUND

We evaluated the outcomes of patients with aortic valve pathology in the setting of a left ventricular ejection fraction ≤35% who underwent minimally invasive aortic valve replacement (AVR), with or without concomitant mitral valve (MV) surgery.

METHODS

All minimally invasive AVR in patients with a left ventricular ejection fraction ≤35%, performed via a right thoracotomy for aortic stenosis or regurgitation between January 2009 and March 2013, were retrospectively evaluated. The operative characteristics, perioperative outcomes, and 30-day mortality were analyzed.

RESULTS

There were 75 patients identified: 51 who underwent isolated AVR, and 24 who had combined AVR plus MV surgery for moderate to severe mitral regurgitation. In patients undergoing MV surgery, there were 22 (91.7%) MV repairs [ring annuloplasty =7 (37.5%), transaortic edge-to-edge repair =15 (62.5%)], and 2 (8.3%) replacements. No patient required conversion to sternotomy for inadequate surgical field exposure. The median total mechanical ventilation time and intensive care unit length of stay were 14 (IQR, 8-20) and 42 hours (IQR, 26-93 hours) in the isolated AVR group, and 16.5 hours (IQR, 12-61.5 hours) and 95.5 hours (IQR, 43.5-159 hours) in the AVR plus MV surgery group, respectively. The most common post-operative complication was new-onset atrial fibrillation, which occurred in 15 (29.4%) isolated AVR and 4 (16.7%) AVR plus MV surgery patients. The median hospital length of stay and 30-day mortality was 7 days (IQR, 5-12 days) and 1 (2%) in the isolated AVR group, and 10.5 days (IQR, 5-21 days) and 1 (4.3%) for AVR plus MV surgery.

CONCLUSIONS

In patients with aortic valve pathology in the setting of a left ventricular ejection fraction ≤35%, minimally invasive AVR can be performed, with or without concomitant MV surgery, with a low morbidity and mortality.

Our Anaesthetic Experiences in Patients Undergoing Percutaneous Mitraclip Implantation

OBJECTIVE

Percutaneous mitraclip implantation system, is a new technique developed for patients with high surgical risks. It is generally performed in a catheterisation laboratory with the guidance of fluoroscopy and transesophageal echocardiography. In this study, we aimed to share our experiences on anaesthetic in patients undergoing mitraclip implantation under general anaesthesia.

METHODS

Eighty four patients with severe, symptomatic mitral insufficiency, who had undergone MitraClip implantation under general anaesthesia between July 2012 and March 2015 (54 male, 30 female; mean age: 68.5±10.2 years) were retrospectively investigated in terms of anaesthetic management.

RESULTS

Of the 84 patients undergoing percutaneous mitraclip implantation under general anaesthesia, 84.5% had sodium thiopental and 75% had midazolam for anaesthesia induction. For the maintenance of anaesthesia, 57% of the patients were reported to have sevoflurane, whereas the rest had desflurane. The mean duration of the procedure and anaesthesia was 140.9±48.2 mins and 165.7±50.6 min, respectively. Seventy seven patients were transported to the intensive care unit and intubated after the procedure. The median extubation time was 3 h. Length of stay in the intensive care unit was 2 days, whereas it was 4 days for hospital stay. One patient died during the procedure and six patients died after the procedure.

CONCLUSION

Percutaneous mitraclip implantation procedure is quite difficult for anaesthesiologists because of the procedure itself and the population on which the procedure is performed. The primary aim of anaesthesia management is to provide haemodynamic stability. The preoperative preparation and anaesthesia methods should be the same as for patients undergoing cardiac surgery. It is reported that as the experience regarding this subject increases, success of the procedure increases, with better protected haemodynamic stability, less inotropic and vasopressor requirement and shorter length of hospital stay.

Transaortic Edge-To-Edge Repair for Functional Mitral Regurgitation during Aortic Valve Replacement: A 13-Year Experience

Objective

The study evaluated the feasibility of a transaortic edge-to-edge mitral valve repair (Alfieri stitch) for moderate or greater (≥2+) functional mitral regurgitation (MR) in high-risk patients undergoing aortic valve replacement.

Methods

We retrospectively evaluated 40 consecutive patients who underwent aortic valve replacement combined with a transaortic edge-to-edge mitral valve repair for 2+ or greater functional MR, between February 2002 and April 2015. The MR was graded semiquantitatively as 0 (trace/none), mild moderate (2+), or moderate to severe (3–4+).

Results

Thirty-two patients had aortic stenosis, and eight had aortic regurgitation. The mean ± standard deviation (SD) age was 77.5 ± 5 years, 34 (85%) were male, and the mean ± SD EuroSCORE II was 14.3% ± 12.9. At a median follow-up of 1 month (interquartile range, 0.75–10), there were significant improvements in preoperative versus postoperative median MR grade (3+ vs 1+, P < 0.001), mean left ventricular ejection fraction (34% vs 41%, P = 0.018), left ventricular end-diastolic diameter (54 vs 49 mm, P = 0.005), and pulmonary artery systolic pressure (49 vs 35 mm Hg, P < 0.001). Persistent 3 to 4+ MR occurred in two patients (5%). In 12 patients with at least 6-month follow-up (mean ± SD, 18 ± 11 months), a sustained improvement in all echocardiographic parameters was observed, with persistent 3 to 4+ MR occurring in one patient (8.3%). Actuarial survival at 1, 3, and 4.5 years was 82% ± 6, 71% ± 8, and 65% ± 10, respectively.

Conclusions

A transaortic edge-to-edge repair for 2+ or greater functional MR can be safely performed during aortic valve replacement and is associated with improvements in MR grade, left ventricular remodeling, and pulmonary hemodynamics.

Effects of Mitral Annulus Remodeling Following MitraClip Procedure on Reduction of Functional Mitral Regurgitation

INTRODUCTION AND OBJECTIVES

The percutaneous mitral valve repair procedure (MitraClip) appears to reduce mitral annulus diameter in patients with functional mitral regurgitation, but the relationship between this and regurgitation severity has not been demonstrated. The aim of this study was to determine the effect of mitral annulus remodeling on the reduction of mitral regurgitation in patients with functional etiology.

METHODS

The study included all patients with functional mitral regurgitation treated with MitraClip at our hospital until January 2015. Echocardiogram (iE33 model, Philips) was performed in all patients immediately after device positioning. Changes in the mitral annulus correlated with mitral regurgitation severity, as assessed using the effective regurgitant orifice area.

RESULTS

The study included 23 patients (age, 65±14 years; 74% men; left ventricular ejection fraction, 31%±13%; systolic pulmonary artery pressure, 47±10 mmHg). After the procedure, the regurgitant orifice area decreased by 0.30 cm²±0.04 cm² (P<.0005), from a baseline of 0.49 cm²±0.09 cm². Anteroposterior diameter decreased by 3.14 mm±1.01 mm (P<.0005) from a baseline of 28.27 mm±4.9 mm, with no changes in the intercommissural diameter (0.50 mm±0.91 mm vs 40.68 mm±4.7 mm; P=.26). A significant association was seen between anteroposterior diameter reduction and regurgitant orifice area reduction (r=.49; P=.020).

CONCLUSIONS

In patients with functional mitral regurgitation, the MitraClip device produces an immediate reduction in the anteroposterior diameter. This remodeling may be related to the reduction in mitral regurgitation.