Long-term outcome of repeated septal reduction therapy after alcohol septal ablation for hypertrophic obstructive cardiomyopathy: insight from the Euro-ASA registry

Management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is an important cause of heart failure and arrhythmias, including sudden death, with a major impact on the healthcare system. Genetic causes and different phenotypes are now increasingly being identified for this condition. In addition, specific medications, such as myosin inhibitors, have been recently shown as potentially able to modify its symptoms, hemodynamic abnormalities and clinical course. Our article aims to provide a comprehensive outline of the epidemiology, diagnosis and treatment of hypertrophic cardiomyopathy in the current era.

Looking Back at 30 Years of Alcohol Septal Ablation and Looking Forward to the Future

In the 30 years since Dr Sigwart's first pioneering procedures, alcohol septal ablation (ASA) has become the standard catheterisation procedure to reduce or eliminate obstruction in the left ventricular outflow tract. This procedure reduces the pressure gradient by 70%-80%, and only 10%-20% of patients have a residual gradient > 30 mm Hg after ASA. The mortality rate of the procedure is < 1%, and ∼ 10% of patients require permanent pacemaker implantation for higher degrees of atrioventricular block. Given the potential risks, ASA should be performed only in centres with extensive experience in the treatment of hypertrophic cardiomyopathy and with comprehensive therapeutic options, including myectomy. In the future, ASA is likely to be increasingly complemented by catheter-based mitral valve repair, which will increase its efficacy.

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.

Outcomes of Alcohol Septal Ablation in Patients With Severe Left Ventricular Outflow Tract Obstruction: A Propensity Score Matching Analysis

BACKGROUND

The current ACC/AHA guidelines on hypertrophic cardiomyopathy (HCM) caution that alcohol septal ablation (ASA) might be less effective in patients with left ventricular outflow tract obstruction (LVOTO) ≥ 100 mm Hg.

METHODS

We used a multinational registry to evaluate the outcome of ASA patients according to baseline LVOTO.

RESULTS

A total of 1346 ASA patients were enrolled and followed for 5.8 ± 4.7 years (7764 patient-years). The patients with baseline LVOTO ≥ 100 mm Hg were significantly older (61 ± 14 years vs 57 ± 13 years; P < 0.01), more often women (60% vs 45%; P < 0.01), and had a more pronounced HCM phenotype than those with baseline LVOTO < 100 mm Hg. There were no significant differences in the occurrences of 30-day major cardiovascular adverse events in the 2 groups. After propensity score matching (2 groups, 257 pairs of patients), the long-term survival was similar in both groups (P = 0.10), the relative reduction of LVOTO was higher in the group with baseline LVOTO ≥ 100 mm Hg (82 ± 21% vs 73 ± 26%; P < 0.01), but the residual resting LVOTO remained higher in this group (23 ± 29 mm Hg vs 13 ± 13 mm Hg; P < 0.01). Dyspnoea (NYHA functional class) at the most recent clinical check-up was similar in the 2 groups (1.7 ± 0.7 vs 1.7 ± 0.7; P = 0.85), and patients with baseline LVOTO ≥ 100 mm Hg underwent more reinterventions (P = 0.02).

CONCLUSIONS

After propensity matching, ASA patients with baseline LVOTO ≥ 100 mm Hg had similar survival and dyspnoea as patients with baseline LVOTO < 100 mm Hg, but their residual LVOTO and risk of repeated procedures were higher.

Invasive therapies for symptomatic obstructive hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic condition with multiple different genetic and clinical phenotypes. As awareness for HCM increases, it is important to also be familiar with potential treatment options for the disease. Treatment of HCM can be divided into two different categories, medical and interventional. Typically for obstructive forms of the disease, in which increased septal hypertrophy, abnormally placed papillary muscles, abnormalities in mitral valve or subvalvular apparatus, lead to dynamic left ventricular outflow tract (LVOT) obstruction, treatment is targeted at decreasing obstructive gradients and therefore symptoms. Medications like beta blockers, calcium channel blockers, disopyramide can often accomplish this. However, in patients with severe obstruction or symptoms refractory to medical therapy, either surgical correction of the LVOT obstruction or percutaneous via alcohol septal ablation, are treatment options. In this review, we will focus on the invasive treatment of hypertrophic obstructive cardiomyopathy.

Hypertrophic Obstructive Cardiomyopathy with SAM Phenomenon: A Case Report and Literature Review

Background

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy (LVH) in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases [1]. It is the most common genetic abnormality of the myocardium, with an anaesthetized prevalence ranging from 1:500 to as high as 1:200 [2-4]. It is the primary cause of sudden cardiac death (SCD) among teenagers and athletes.

Patient

A 56-year-old man presented with chest tightness and palpitations which had been occurring post-activity for the previous 6 months. The patient was advised to be admitted. He underwent echocardiography, cardiac magnetic resonance (CMR), coronary angiography (CAG) examination, and left ventriculography. He was diagnosed with hypertrophic obstructive cardiomyopathy (HOCM) with systolic anterior motion (SAM) phenomenon.

Results

Echocardiography results showed that the interventricular septal thickness was 14-16 mm and that there were 2 degrees of SAM of the mitral valve. This resulted in severe stenosis of the left ventricular outflow tract (LVOT) and moderate to severe mitral insufficiency. Left ventriculography confirmed mitral regurgitation (MR) associated with HOCM with SAM phenomenon. Under the protection of a permanent pacemaker, the patient was treated with alcohol septal ablation (ASA). After discharge, the symptoms of chest tightness and palpitation did not recur.

Conclusion

Beneficial effects were observed when patients with HOCM and SAM were treated with ASA under the condition of a permanent pacemaker.

Left ventricular outflow tract obstruction in hypertrophic cardiomyopathy and the impact of mavacamten

Hypertrophic cardiomyopathy (HCM) is a common genetic disorder characterised by unexplained left ventricular hypertrophy. Left ventricular outflow tract obstruction is an integral component of the disease, often resulting in significant symptoms, but also carrying a risk of progression to heart failure and death. Advancements in our understanding of the pathophysiology of HCM have led to the development of new therapies targeting the molecular basis of the disease at the level of the cardiac sarcomere, the basic contractile apparatus of the myocardium. Myosin modulators are a novel class of small molecules which target cardiac myosins directly to modulate cardiac contractility. The myosin inhibitors present the first advancement in pharmacological management of obstructive HCM in almost 35 years, with a growing body of evidence for the safety, tolerability and efficacy of mavacamten, and to a lesser extent aficamten. The aim of this review is to summarise the current management of patients with obstructive HCM and review the most recent available data from clinical trials pertaining to myosin inhibition.

Prediction of Sudden Cardiac Arrest After Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy: ASA-SCARRE Risk Score

This study aimed to derive a new score, the Alcohol Septal Ablation-Sudden Cardiac ARREst (ASA-SCARRE) risk score, that can be easily used to evaluate the risk of sudden cardiac arrest events (sudden cardiac death, resuscitation, or appropriate implantable cardioverter-defibrillator discharge) after alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy. We analyzed 1,834 patients from the Euro-ASA registry (49% men, mean age 57 ± 14 years) who were followed up for 5.0 ± 4.3 years (9,202 patient-years) after ASA. A total of 65 patients (3.5%) experienced sudden cardiac arrest events, translating to 0.72 events per 100 patient-years. The independent predictors of sudden cardiac arrest events were septum thickness before ASA (hazard ratio 1.09 per 1 mm, 95% confidence interval 1.04 to 1.14, p <0.001) and left ventricular outflow tract (LVOT) gradient at the last clinical checkup (hazard ratio 1.01 per 1 mm Hg, 95% confidence interval 1.01 to 1.02, p = 0.002). The following ASA-SCARRE risk scores were derived and independently predicted long-term risk of sudden cardiac arrest events: "0" for both LVOT gradient <30 mmHg and baseline septum thickness <20 mm; "1" for LVOT gradient ≥30 mm Hg or baseline septum thickness ≥20 mm; and "2" for both LVOT gradient ≥30 mm Hg and baseline septum thickness ≥20 mm. The C statistic of the ASA-SCARRE risk score was 0.684 (SE 0.030). In conclusion, the ASA-SCARRE risk score may be a useful and easily available clinical tool to predict risk of sudden cardiac arrest events after ASA in patients with hypertrophic obstructive cardiomyopathy.

Targeting Alcohol Septal Ablation in Patients with Obstructive Hypertrophic Cardiomyopathy Candidates for Surgical Myectomy: Added Value of Three-Dimensional Intracoronary Myocardial Contrast Echocardiography

Background: Myocardial contrast two-dimensional echocardiography (MC-2DE) is widely used to address alcohol septal ablation (ASA) in obstructive hypertrophic cardiomyopathy (HCM). Owing to its limited cut-planes, MC-2DE may inaccurately identify the contrast misplacement associated with an unsuccessful or complicated ASA outcome. Objective: The aim of this study was to assess the added value of myocardial contrast three-dimensional echocardiography (MC-3DE) compared with MC-2DE to identify the appropriate matching between the target septal zone (TSZ) and coronary artery branch for safe and long-term effective ASA in HCM patients. Methods: A consecutive series of 52 symptomatic obstructive HCM patients referred for isolated surgical myectomy (SM) was analyzed with MC-2DE and MC-3DE following injection of echocontrast into one or more septal branches. MC-2DE and MC-3DE patterns were categorized according to complete (Type 1) or incomplete (Type 2) TSZ covering, high-risk (Type 3) exceeding TSZ, or life-threatening outside TSZ distribution (Type 4). Results: MC-2DE per patient analysis showed a Type 1 pattern in 32 patients and Types 2–4 in the remaining 20 patients; subsequent MC-3DE analysis provided a re-phenotyping of MC-2DE findings in 22 of the 52 patients (42%), showing a high-risk Type 2 pattern in 17 of the 32 patients with Type 1, and a new life-threatening Type 4 in three patients with Type 2, respectively. All patients with MC-3DE Type 1 pattern underwent safe and effective ASA with a long-term uneventful follow-up, while the remaining patients underwent SM. Conclusions: Refining high risk or life-threatening contrast misplacement, MC-3DE is more accurate than conventional MC-2DE to target safe and long-term effective septal reduction with ASA in obstructive HCM patients referred for isolated SM.