Alcohol septal ablation versus surgical septal myectomy of obstructive hypertrophic cardiomyopathy: systematic review and meta-analysis

Transcatheter Myotomy for Hypertrophic Obstructive Cardiomyopathy

PURPOSE OF REVIEW

To describe the emerging role of transcatheter septal myotomy in the treatment of hypertrophic obstructive cardiomyopathy.

RECENT FINDINGS

Transcatheter septal myotomy was developed to address risk of LVOT obstruction during TMVR, however it has been performed in patients with LVOT obstruction related to hypertrophic cardiomyopathy, in whom it improves symptoms, reduces LVOT gradients, and is associated with low incidence of procedural complications. Transcatheter myotomy is a novel approach to address LVOT obstruction related to hypertrophic cardiomyopathy in patients who are not favorable surgical candidates. The risk of conduction abnormalities with transcatheter septal myotomy appears low. Research is needed to define optimal patient selection and long-term outcomes.

Modern Perspectives on Hypertrophic Cardiomyopathy-No One Size Fits All

Despite substantial advances in the management of hypertrophic cardiomyopathy, advanced heart failure remains a major cause of morbidity in this patient population. This narrative review presents the case of a patient with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation to frame a discussion of modern therapies for hypertrophic cardiomyopathy. The current treatment landscape includes medications, both old and new, and surgical and procedural interventions to relieve mechanical obstruction. Several promising new modalities for relieving obstruction are in the nascent stages of development.

Invasive Management of Hypertrophic Cardiomyopathy With Clinically Important Obstruction: Surgical Myectomy Is Superior, but Only When Accessible

For patients with hypertrophic cardiomyopathy (HCM), a thickened intraventricular septum and systolic anterior motion of the mitral valve (SAM) can contribute to significant left ventricular outflow tract obstruction (LVOTO), mitral regurgitation, and debilitating symptoms. Current guidelines recommend septal reduction therapy through alcohol septal ablation or surgical septal myectomy for patients whose symptoms persist despite medical therapy. Although alcohol septal ablation is a less invasive treatment option, it is not suitable for patients with septal perforator branch anatomy that is not compatible with the procedure, those with midcavitary obstruction, and patients in whom the mechanism of LVOTO is primarily related to SAM. Septal ablation also has a notably higher rate of atrioventricular block requiring permanent pacemaker insertion, and the need for reintervention has been reported to be 15% or more. In contrast, septal myectomy offers direct visualisation and can address thickened septum and mitral valve (MV) anomalies. It can be used to treat a wider variety of anatomies, with lower rates of reoperation. Aside from the more invasive nature of the procedure, a major limitation of septal myectomy, however, is access, because relatively few surgeons specialise in the procedure. This is important because there is a significant correlation between procedural volumes and outcomes. Patients should be evaluated by a multidisciplinary heart team to ensure that they are aware of all treatment options. In this review, we explore the 2 methods of septal reduction therapy and highlight the need for further training of septal myectomy surgeons to ensure access to optimal septal reduction therapies for Canadian patients with HCM.

Interventions in Hypertrophic Obstructive Cardiomyopathy

Obstructive hypertrophic cardiomyopathy is the most common genetically transmitted cardiomyopathy that is associated with significant morbidity and mortality. Despite contemporary treatments and interventions, the management of patients with obstructive hypertrophic cardiomyopathy remains poorly defined compared with other branches of cardiology. In this review, we discuss established and novel therapeutic interventions in patients with obstructive hypertrophic cardiomyopathy with a focus on percutaneous and surgical strategies including surgical myectomy, mitral valve repair or replacement, percutaneous alcohol septal ablation, pacemaker and cardioverter-defibrillator implantation, septal embolization, radiofrequency endocardial catheter ablation, and percutaneous intramyocardial septal radiofrequency ablation.

Alcohol Septal Ablation or Mavacamten for Obstructive Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterized by an increased left ventricular wall thickness in the absence of increased afterload conditions. In addition to diastolic dysfunction, obstruction of the left ventricular outflow tract is common in HCM and has an important influence on symptoms and outcome. Over the last five decades or two decades, respectively, surgical myectomy and alcohol septal ablation were the only therapeutic options if standard medical care was not sufficient. Recently, a new option has become available that has the potential to revolutionize the therapeutic strategies for patients with HCM. Mavacamten is a myosin inhibitor that belongs to a completely new drug class and targets the excessive actin-myosin cross-bridging that is the underlying pathology of HCM. By reducing the actin-myosin interactions, mavacamten not only reduces the left ventricular outflow tract (LVOT) obstruction but also seems to have positive effects on the diastolic function, microcirculation, and cardiac structure. This article summarizes the current evidence on alcohol septal ablation and reviews the preclinical and clinical data on mavacamten for the treatment of patients with obstructive HCM.