Continuous rhythm monitoring for ventricular arrhythmias after alcohol septal ablation for hypertrophic cardiomyopathy

Usefulness of insertable cardiac monitors for risk stratification: current indications and clinical evidence

INTRODUCTION

The 2018 ESC Syncope guidelines expanded the indications for an insertable cardiac monitor (ICM) to patients with unexplained syncope and primary cardiomyopathy or inheritable arrhythmogenic disorders.

AREAS COVERED

This review article discusses the clinical evidence for using an ICM for risk stratification in different patient populations including Brugada syndrome, long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis, and congenital heart disease.

EXPERT OPINION

Clinical data on the usefulness of ICMs in different patient populations is limited but most studies demonstrate early detection of clinically relevant arrhythmias, such as nonsustained ventricular tachycardia or atrial fibrillation. It is important to emphasize that the study populations usually comprise selected populations where conventional diagnostic methods fail to clarify the mechanism of symptoms. The effect of an ICM on prognosis by earlier detection of arrhythmias is difficult to demonstrate in populations with rare disease. Risk stratification in patients with cardiomyopathy or inheritable arrhythmogenic disorders remains a niche indication for ICMs. The most important indication for an ICM remains unexplained syncope in patients at low risk of SCD. Given the device costs and uncertain clinical value of device-detected arrhythmias, it is unclear whether it is also useful in non-syncopal patients.

A Narrative Review of Emerging Therapies for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy is a hereditary condition that affects myocardial contraction. In case of failure of pharmacological treatment, alternative approaches might be used that include surgical myectomy, percutaneous transluminal septal myocardial ablation, and radiofrequency ablation. In respect of long-term advantages, surgical septal myectomy remains the therapy of choice for symptomatic hypertrophic obstructive cardiomyopathy. Alcohol septal ablation has been considered an alternative to surgical myectomy, which confers the benefits of a shorter hospital stay, less discomfort, and fewer complications. However, only expert operators should perform it on carefully chosen patients. Further, radiofrequency septal ablation reduces the left ventricular outflow tract gradient and improves the NYHA functional class of patients with hypertrophic obstructive cardiomyopathy, despite complications like cardiac tamponade and atrioventricular block. Further research with a larger sample size is required to compare the radiofrequency approach with established invasive treatment methods for hypertrophic obstructive cardiomyopathy. Septal myectomy has low morbidity and mortality rates, making it the preferred procedure; however, the efficacy and morbidity remain debatable. Advances in invasive techniques, including percutaneous septal radiofrequency ablation and transcatheter myotomy, have provided alternative approaches for reducing left ventricular outflow tract (LVOT) obstruction in patients who are not candidates for traditional surgical septal myectomy. Candidates for alcohol and radiofrequency septal ablation include patients with symptomatic hypertrophic obstructive cardiomyopathy, older adults, and those with multiple comorbidities.

Percutaneous Intramyocardial Septal Radiofrequency Ablation in Patients With Drug-Refractory Hypertrophic Obstructive Cardiomyopathy

Importance

Patients with hypertrophic obstructive cardiomyopathy (HOCM) and drug-refractory symptoms and outflow gradients have limited nonsurgical treatment options. The feasibility of percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) has been reported previously; however, procedural and medium-term outcomes are unknown.

Objective

To describe the safety and medium-term outcomes of PIMSRA in a large patient cohort with drug-refractory HOCM.

Design, Setting, and Participants

This was a single-arm, open-label study of PIMSRA in patients with drug-refractory HOCM. Patients presenting to the Xijing Hospital in Xi'an, China, between October 2016 to June 2020 with hypertrophic cardiomyopathy. Of 1314 patients presenting with HOCM, 244 fulfilled inclusion criteria of severe resting/provoked outflow gradients of 50 mm Hg or higher, and symptoms of New York Heart Association functional class of II or higher refractory to maximum tolerated medications. After discussion among the heart team, 40 patients underwent surgical or alcohol septal reduction therapy and 4 required treatment of significant coronary artery disease.

Interventions

PIMSRA performed in patients.

Main Outcomes and Measures

The primary outcome was 30-day major adverse clinical events: death, emergency surgery, severe effusion requiring intervention, procedure-related stroke, bleeding, and stroke. Secondary outcomes included 30-day technical success and 90-day improvement in outflow obstruction.

Results

The mean (SD) age of 200 patients was 46.9 (14.0) years, and 125 (62.5%) were men. Resting or provoked left ventricular outflow tract gradients were 50 mm Hg or higher. The median (IQR) follow-up for all patients was 19 (6-50) months. Thirty-day major adverse clinical events rate was 10.5% (n = 21): there were 2 in-hospital/30-day deaths (1.0%), 7 patients (3.5%) with pericardial effusion requiring mini-thoracotomy, 12 patients (6%) with pericardial effusion requiring pericardiocentesis, and no bleeding or strokes. Other periprocedural complications included permanent right bundle branch block in 5 patients (2.5%), resuscitated ventricular fibrillation in 2 (1.0%), and septal branch aneurysm in 2 (1.0%). There were no permanent pacemaker implantations. At follow-up, maximum septal thickness was reduced from a mean (SD) of 24.0 (5.1) mm to 17.3 (4.4) mm (P < .001), and left ventricular outflow tract gradient was decreased from a mean (SD) of 79.0 (53.0) mm Hg to 14.0 (24.0) mm Hg (P < .001). Overall, 190 patients (96%) with HOCM were in New York Heart Association functional class I or II at last follow-up.

Conclusions and Relevance

This study found that PIMSRA in patients with drug-refractory HOCM may be an effective procedure for relief of left ventricular outflow tract obstruction and symptoms with acceptable complication rates. These results are encouraging and support the design of a randomized clinical trial against well-established septal reduction therapies.

Arrhythmia monitoring for risk stratification in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy, presenting significant clinical heterogeneity. Arrhythmia risk stratification and detection are critical components in the evaluation and management of all cases of HCM. The 2020 American Heart Association/American College of Cardiology HCM guidelines provide new recommendations for periodic 24-48-hour ambulatory electrocardiogram monitoring to screen for atrial and ventricular arrhythmias. A strategy of more frequent or prolonged monitoring would lead to earlier arrhythmia recognition and the potential for appropriate treatment. However, whether such a strategy in patients with HCM results in improved outcomes is not yet established. The available evidence, knowledge gaps, and potential merits of such an approach are reviewed. Cardiac implantable electronic devices provide an opportunity for early arrhythmia detection, with the potential to enable early management strategies in order to improve outcomes.

Looking back on 15 years of ultrasound-guided alcohol septal ablation for hypertrophic obstructive cardiomyopathy

Background: Septal reduction remains an important target of current therapeutic modalities in hypertrophic obstructive cardiomyopathy (HOCM). Surgical septal myectomy has long been considered the gold standard in pharmacotherapy-refractory severely symptomatic patients with marked left ventricular outflow tract (LVOT) obstruction. In recent years, percutaneous alcohol septal ablation (ASA) has matured into the preferred strategy for patients with favourable anatomy and no other coexisting surgically amenable disease.Methods: We discuss 26 HOCM patients with persistent dyspnoea, angina or syncope despite optimal medical treatment. Baseline septal wall thickness was 20 ± 3 mm, with peak resting/provoked LVOT gradients of 53 ± 35/112 ± 40 mmHg. Guided by echocardiography, alcohol injection could be restricted to the first septal coronary artery in 85% of patients, provoking basal septal infarction with average troponin rise of 3.0 ng/ml.Results: Eighty-six per cent of patients experienced sustained clinical improvement, associated with a reduction of septal wall thickness to 15 ± 3 mm and resting LVOT gradient to 21 ± 15 mmHg. One of the two non-responders underwent additional septal myectomy 11 years after ASA. Notable adverse events during the follow-up of 7.2 ± 4.7 years included: persistent conduction disturbances (65%) necessitating early postprocedural permanent pacemaker implantation (15%); atrial fibrillation (32%); ventricular tachycardia (4%) and aortic stenosis (14%). Six patients died, of which only 1 cardiac death.Conclusions: Our case series underscores the efficacy of ASA at relieving LVOT obstruction and improving symptoms in properly selected HOCM patients, with acceptably low procedural and long term mortality and morbidity.

Risk of arrhythmic events after alcohol septal ablation for hypertrophic cardiomyopathy using continuous implantable cardiac monitoring

BACKGROUND

Alcohol septal ablation (ASA) in patients with hypertrophic cardiomyopathy (HCM) can lead to heart rhythm disturbances including complete heart block (CHB) and atrial and ventricular arrhythmias.

OBJECTIVE

We aimed to evaluate the utility of long-term arrhythmia monitoring with an implantable cardiac monitor (ICM) after ASA.

METHODS

Between February 2014 and March 2019, 56 patients with HCM undergoing ASA were enrolled in a prospective study and underwent ICM implantation. Kaplan-Meier survival analysis was used to assess the rate of ICM-detected arrhythmic events.

RESULTS

The mean age was 59 ± 11 years, and 20 (36%) were women. The median (25th, 75th percentile) resting left ventricular outflow tract gradient obtained by echocardiography was 43 (22, 81) mm Hg. Greater than 1 septal perforating artery was injected in 48 patients (86%). The Kaplan-Meier cumulative rate of ICM-detected arrhythmic events at 18 months of follow-up was 71%, with an event rate of 43% occurring within 3 months of ASA. The cumulative rate of the ICM-detected first atrial fibrillation event at 18 months was 37%, and the corresponding rate of CHB was 19%. All atrial fibrillation and CHB events were actionable, leading to the initiation of anticoagulation and pacemaker implantation, respectively. No baseline demographic or procedural variables were identified as independent predictors of an increased risk of developing ICM-detected arrhythmic events.

CONCLUSION

After ASA, ICM is effective in capturing clinically actionable arrhythmic events in patients with HCM regardless of patient's baseline risk factors.

Temporal Occurrence of Arrhythmic Complications After Alcohol Septal Ablation

BACKGROUND

The temporal occurrence of arrhythmic complications after alcohol septal ablation (ASA) is unclear. As a result, the appropriate time to monitor patients after ASA is controversial. The purpose of this study is to determine the temporal occurrence of complete heart block (CHB) and ventricular tachyarrhythmia (VT) after ASA to better understand when patients can be safely discharged.

METHODS

Consecutive patients treated with ASA for hypertrophic cardiomyopathy from 2003 to 2019 at a tertiary referral center were reviewed retrospectively. The incidence and timing of CHB or sustained VT within 30 days post-ASA were assessed.

RESULTS

A total of 243 patients were included in this study. Mean maximal septal thickness was 19.0±3.9 mm, and total volume of ethanol injected was 1.7±0.6 mL. CHB occurred in 59 (24.3%) patients, including transient CHB in 33 (13.6%) and permanent in 26 (10.7%). The initial episode of CHB occurred within 24 hours post-ASA in 51 (21.0%) patients, between 24 and 48 hours in 3 (1.2%), between 48 and 72 hours in 3 (1.2%), and after 72 hours in 2 (0.8%). New permanent pacemaker was placed in 46 (18.3%). Presence of baseline bundle branch block and age ≥70 were significantly associated with CHB but not CHB presenting after 24 hours. VT occurred in 3 (1.2%) patients, including 1 (0.4%) within 24 hours, 1 (0.4%) between 24 and 48 hours, and 1 (0.4%) after 72 hours. VT required cardioversion in 2 patients and new implantable cardioverter-defibrillator placement in 2.

CONCLUSIONS

The incidence of CHB or VT presenting after 72 hours post-ASA was low. These findings suggest that timely discharge of patients without evidence of early conduction disturbances after ASA can be considered as a potentially safe management strategy, especially in patients without preexisting conduction abnormalities.

Hypertrophic obstructive cardiomyopathy: what, when, why, for whom?

Hypertrophic cardiomyopathy is the most common genetic cardiovascular disorder and is associated with symptoms of heart failure and increased risk of sudden cardiac death. The most common condition is obstruction of the left ventricular outflow tract. Surgical septal myectomy and alcohol septal ablation are the 2 accepted modes of septal reduction therapy and are indicated when there are advanced symptoms and a peak left ventricular outflow gradient ≥50 mmHg. Advantages of alcohol septal ablation are limited groin approach, reduction of obstruction of the left ventricular outflow tract and functional improvement, but there are higher chances for intracardiac device implantation and residual obstruction. Septal myectomy offers very low mortality, absolute and immediate resolution of obstruction of the left ventricular outflow tract and survival comparative to a matched general population with almost negligible residual obstruction. It is recommended that patients with obstructive hypertrophic cardiomyopathy should be treated at experienced centres.

[Indications for implantable loop recorders in patients with channelopathies and ventricular tachycardias]

Implantable loop recorders (ILR) do not play a pivotal role in the current guidelines on ventricular arrhythmias except in identifying rhythm-symptom correlations if ventricular arrhythmias are assumed. Before a decision for a pure diagnostic implantable device is made, a thorough arrhythmic risk assessment is of major importance due to the potential lethal outcome of ventricular arrhythmias. Nevertheless, some clinical circumstances exist where long-term monitoring by an ILR may add significant information in electrical heart diseases, in patients with ventricular arrhythmias, or structural heart diseases and a potential risk of ventricular arrhythmias. As medical therapy (β-blocker therapy) plays an important role in long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardias (cpVT), the ILR can be used to control therapy in patients at risk. In electrical diseases without pharmacologic therapeutic options (e. g., Brugada syndrome), the ILR may be used in low-risk patients with atypical syncope as benign faints may occur without association to the underlying disease. Evidence on cardiomyopathies with preserved left ventricular function and nonsustained VT or premature ventricular complexes is scarce. The ILR may also add long-term information on the individual risk in these circumstances. In very rare diseases like infiltrative disease or muscular dystrophies, the ILR may also provide evidence on risk stratification. In summary, ILR in electrical heart diseases and in patients with ventricular tachycardia remains a very individual decision taking into account various clinical, electrocardiographic, and genetic parameters. The following review aims at highlighting possible indications and clinical scenarios for ILR in ventricular tachycardias and electrical heart diseases with-probably debatable-case presentations.

Low occurrence of ventricular arrhythmias after alcohol septal ablation in high-risk patients with hypertrophic obstructive cardiomyopathy

INTRODUCTION

Percutaneous alcohol septal ablation (PTSMA) is an established treatment for symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). However, there is concern of a higher risk for ventricular tachyarrhythmias and sudden death due to the myocardial scar created after PTSMA. We investigated the possibility of increased ventricular arrhythmias and risk of sudden death after PTSMA in a subgroup of patients with an already implanted ICD.

METHODS AND RESULTS

Between 2009 and 2012, 239 PTSMAs were performed in 212 patients with HOCM. In 32 of those an ICD had already been implanted before PTSMA for primary (31 patients) or secondary (1 patient) prevention of sudden death. The maximum left ventricular outflow tract gradient (LVOTG) was reduced from 114 ± 39 mmHg before PTSMA to 23 ± 19 mmHg (P < 0.0001). Among clinical risk factors for sudden death, nonsustained ventricular tachycardia (VT), syncope and family history for sudden death were most common. After a median follow-up of 5.3 (IQR 4.3-5.7) years after PTSMA only one patient had ICD shocks (annual ICD discharge 0.6 %). In another 3 patients, with already documented nonsustained VTs as risk factor before ICD implantation, VT episodes that activated antitachycardic pacing were recorded. The annual appropriate ICD intervention including all events was 2.5 % and involved only patients with a very high estimated 5-year sudden death risk before PTSMA (>14.3 %).

CONCLUSIONS

In a selected high-risk patient cohort with HOCM ominous arrhythmic events seem to be rare and predominantly occur in patients with a very high estimated risk of sudden death before PTSMA.