Transcatheter Therapies for the Treatment of Valvular and Paravalvular Regurgitation in Acquired and Congenital Valvular Heart Disease

Interventions for Congenital Atrioventricular Valve Dysfunction: JACC Focus Seminar

Innovation and creativity have led to tremendous advancements in the care and management of patients with congenital heart disease (CHD) that have resulted in considerably increased survival. Catheter-based interventions have contributed significantly to these advancements. However, catheter-based interventions for congenital lesions of the atrioventricular (AV) valves have been limited in scope and effectiveness mainly because of patient size and anatomical challenges. Thus, surgical repair and replacement for congenital AV valve lesions have remained the preferred therapy. However, the ongoing transcatheter heart valve revolution has led to techniques and technologies that are changing the landscape, particularly for adult CHD patients. Many devices for AV valve repair and replacement are being studied in adult patients without CHD, and translation of select practices to CHD patients has begun, with many more to come. Transcatheter AV valve interventions represent exciting opportunities for the growing numbers of adult CHD patients.

Transcatheter mitral valve implantation using a novel system: preclinical results

BACKGROUND

This preclinical study in sheep sought to demonstrate the initial safety and feasibility of a novel transcatheter mitral valve system (Mi-thos valve) composed of a self-expanding frame and a bovine pericardial tissue bioprosthesis.

METHODS

The valve was implanted in 26 sheep using a transapical approach for short- and long-term evaluation. The technical feasibility, safety, durability, and valve function were evaluated during and 6 months after the procedure using intracardiac and transthoracic echocardiography, multisliced computed tomography, histological analysis, and electron microscopy.

RESULTS

The success rate of valve implantation was 100%, and the immediate survival rate after surgery was 84%. Five animals died within 90 min after the development of the prosthetic valve due to an acute left ventricular outflow tract obstruction (n = 2) and sudden intraoperative ventricular fibrillation (n = 3). Twelve animals died within 1 month due to acute left heart dysfunction. Mild (n = 5) and moderate (n = 2) paravalvular leakage occurred in seven animals, and two moderate PVL animals died of chronic heart failure within three months. Multimodality imaging studies of the remaining seven animals showed excellent function and alignment of the valves, with no coronary artery obstruction, no left ventricular outflow tract obstruction, no severe transvalvular gradients and no paravalvular leakage. Macroscopic evaluation demonstrated stable, secure positioning of the valve, with full endothelialization of the valve leaflets without injury to the ventricular or atrial walls. Histological and electron microscopic examinations at six months showed no obvious macro- or microcalcification in the leaflets.

CONCLUSIONS

Preclinical studies indicate that transcatheter implantation of the Mi-thos valve is technically safe and feasible. The durability, functionality, and lack of leaflet calcification were all verified in animal experiments. The information from these preclinical studies will be applied to patient selection criteria and the first-in-human studies.

Contemporary Management of Ischemic Mitral Regurgitation: A Review

Ischemic mitral regurgitation occurs relatively frequently in patients with coronary artery disease and is associated with an increased long-term risk. The pathophysiology of ischemic mitral regurgitation is vexing and poses both diagnostic and therapeutic challenges, leading to the need for a comprehensive, multidisciplinary approach. The management is largely focused on medical therapy, and for those eligible, coronary revascularization or cardiac resynchronization therapy may be considered. In select patients, mitral valve surgery or catheter-based therapy may be undertaken with careful consideration of the underlying pathophysiology, surgical risk, and expected long-term outcomes. The appropriate evaluation of patients with ischemic mitral regurgitation involves a careful multidisciplinary approach that carefully considers symptomatology, the etiology and severity of the mitral regurgitation, and the assessment of comorbidities and operative risk to individualize the care of these patients.

Current Management of Patients with Severe Aortic Regurgitation

OPINION STATEMENT

Chronic aortic regurgitation can result from various congenital and acquired anomalies and can be associated with proximal aortic disease. As the number of aortic valve procedures is growing, the incidence of post-procedural regurgitation also increases with associated morbidity. Typical evolution is characterized by a clinically silent phase of variable duration followed by a rather rapid decline with high incidence of adverse events. A challenge remains to find the optimal timing for an intervention: Patients are exposed to unnecessary surgical risks if treated prematurely, but peri- and post-operative prognosis is worse when the intervention is performed too late. Clinical evaluation and serial imaging tests can optimize the timing for intervention. Clinical follow-up should try to elucidate associated symptoms, with quantitative measurement of functional capacity as needed. Serial imaging examinations are required to identify sub-clinical left ventricular dysfunction or severe dilatation that should prompt a surgery. At least in selected cases, newer imaging modalities (MRI, 3D echocardiography) and/or biomarkers can help for the management of these patients, and more research is needed to determine if their systematic use can be beneficial. Medical treatment with vasodilators and anti-remodeling drugs can be helpful in some patients but should not replace or delay aortic valve surgery when indicated. Most patients will eventually be treated with surgical aortic valve replacement. Although possible in selected cases, transcatheter aortic valve replacement is not commonly used for patients with pure aortic regurgitation. For patients with prior aortic valve replacement and aortic regurgitation (paravalvular or intravalvular), emerging percutaneous approaches can be considered when available, especially for those at high surgical risk.

Surgical Transapical Approach for Prosthetic Mitral Paravalvular Leak Closure: Early Results

The objective is to demonstrate safety and early clinical results of surgical transapical closure of paravalvular leaks (PVLs) following mitral valve replacement in significant regurgitation. Between March 2014 and February 2015, 12 patients (mean age 52.1 ± 6.0 years, 66.6% male) with severe symptomatic mitral PVLs (n = 13) underwent surgical transapical closure procedure through left mini-thoracotomy. All patients were in NYHA functional class III-IV and median logistic EuroSCORE was 24.2 ± 6.4% (range, 13.5-34.6%). Indications were heart failure (n = 10) and symptomatic hemolysis (n = 2) due to severe mitral regurgitation (MR). Amplatzer Vascular Plug-III devices (n = 9) were used for smaller and regular defects; whereas Atrial Septal Defect closure devices (n = 4) were used for larger defects. Technical success was achieved in 10 (83.3%) patients. One (8.5%) patient with 2 + MR was treated medically. A patient with residual 4 + MR underwent re-operation. There was no procedure-related complication including mortality, device migration, embolization, or cardiac laceration. Mean procedure and fluoroscopy times were 166.4 ± 39.5 (range, 90-210) and 25.7 ± 17.3 (range, 16-64) minutes, respectively. The mean intensive care and hospital stays were 2.1 ± 1.3 and 10.3 ± 6.5 days, respectively. Clinical efficacy was achieved in 9 (75%) of 12 patients at early follow-up of 8.5 ± 2.1 months. NYHA status was class II in two patients, and no hemolytic anemia was diagnosed. Echocardiographic studies revealed a significant reduction of preoperative MR (3-4+) to less than 1+ MR after operations (P < 0.05). Surgical transapical approach to PVL closure is a safe and effective procedure following mitral valve replacement. Early results show that this procedure can be an alternative to re-operation for high-risk patients. Further studies are needed to prove its effectiveness in the long term.

Role of Imaging Techniques in Percutaneous Treatment of Mitral Regurgitation

Mitral regurgitation is the most prevalent valvular heart disease in the United States and the second most prevalent in Europe. Patients with severe mitral regurgitation have a poor prognosis with medical therapy once they become symptomatic or develop signs of significant cardiac dysfunction. However, as many as half of these patients are inoperable because of advanced age, ventricular dysfunction, or other comorbidities. Studies have shown that surgery increases survival in patients with organic mitral regurgitation due to valve prolapse but has no clinical benefit in those with functional mitral regurgitation. In this scenario, percutaneous repair for mitral regurgitation in native valves provides alternative management of valvular heart disease in patients at high surgical risk. Percutaneous repair for mitral regurgitation is a growing field that relies heavily on imaging techniques to diagnose functional anatomy and guide repair procedures.

Mitral clip - looking back and moving forward

PURPOSE OF REVIEW

Guidelines indicate surgical intervention for patients with symptomatic severe mitral regurgitation or signs of left ventricular dilatation or dysfunction. However, many patients do not receive surgery because of age or comorbidities, and have poor outcomes with conservative therapy. Transcatheter mitral repair with MitraClip (Abbott Vascular, IL, USA) has recently emerged as a viable treatment option for high-risk patients with heart failure. This article will review current evidence supporting the use of MitraClip across the spectrum of patient risk and discuss future directions for this technology.

RECENT FINDINGS

Both randomized and registry studies have demonstrated the efficacy and safety of MitraClip for mitral regurgitation reduction, with significant improvements in functional class and reductions in heart failure hospitalizations. With increasing global experience, a broader scope of patients and diseases can now be successfully treated, ranging from patients with failed surgical annuloplasty rings to those in cardiogenic shock. Ongoing randomized trials will further define the role of MitraClip in the management of heart failure patients with secondary mitral regurgitation.

SUMMARY

MitraClip is a useful therapeutic tool for nonsurgical patients with advanced heart failure and severe mitral regurgitation. Further developments in device design and procedural technique will continue to expand the range of patients who can be treated, with a goal of reducing heart failure hospitalizations and improving quality of life.

Computed Tomography for Structural Heart Disease and Interventions

Transcatheter cardiac interventions are a fast evolving field. The past decade has seen the development of transcatheter aortic valve replacement, transcatheter mitral valve repair and replacement, septal defect closure devices and left atrial appendage closure devices for thromboprophylaxis. More than ever, medical imaging is taking a central role in the care of patients with structural heart disease. In this review article we outline the use of MSCT as a tool for diagnosis of structural heart interventions, as well as patient selection, pre-procedural planning, device sizing and post-procedural assessment. We focus on procedures targeting the aortic valve, the mitral valve, the inter-atrial septum and the left atrial appendage.