EvaLuation Using Cardiac Insertable Devices And TelephonE in Hypertrophic Cardiomyopathy (ELUCIDATE HCM): A prospective observational study on incidence of arrhythmias

Atrial Fibrillation in Hypertrophic Cardiomyopathy

Atrial fibrillation (AF) is common among patients with hypertrophic cardiomyopathy (HCM) with a prevalence greater than 25%. AF in HCM is associated with a high risk of stroke and can be a marker of more advanced cardiomyopathy. Although, it frequently results in cardiac hemodynamic changes which are poorly tolerated, it can be subclinical. Thus, prompt diagnosis and adequate management of AF are essential to minimizing AF-related adverse outcomes in HCM. All HCM patients should be screened for AF regularly, and those with high-risk features should be screened more frequently preferably with extended ambulatory monitoring. Once AF is detected, oral anticoagulation should be initiated. Both general and HCM-specific modifiable risk factors should be addressed and assessment for cardiomyopathy progression should be performed. Although no randomized controlled studies have compared rate versus rhythm control in HCM, early rhythm control could be considered to prevent further LA remodeling.

Prolonged mHealth-Based Arrhythmia Monitoring in Patients With Hypertrophic Cardiomyopathy (HCM-PATCH): Protocol for a Single-Center Cohort Study

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) are at increased risk of sudden cardiac death (SCD) due to ventricular arrhythmias and other arrhythmias. Screening for arrhythmias is mandatory to assess the individual SCD risk, but long-term electrocardiography (ECG) is rarely performed in routine clinical practice. Intensified monitoring may increase the detection rate of ventricular arrhythmias and identify more patients with an increased SCD risk who are potential candidates for the primary prophylactic implantation of an implantable cardioverter-defibrillator. To date, reliable data on the clinical benefit of prolonged arrhythmia monitoring in patients with HCM are rare.

OBJECTIVE

This prospective study aims to measure the prevalence of ventricular arrhythmias in patients with HCM observed by mobile health (mHealth)-based continuous rhythm monitoring over 14 days compared to standard practice (a 24- and 48-h long-term ECG). The frequency of ventricular arrhythmias in this 14-day period is compared with the frequency in the first 24 or 48 hours for the same patient (intraindividual comparison).

METHODS

Following the sample size calculation, 34 patients with a low or intermediate risk for SCD, assessed by the HCM Risk-SCD calculator, will need to be recruited in this single-center cohort study between June 2023 and February 2024. All patients will receive an ECG patch that records their heart activity over 14 days. In addition, cardiac magnetic resonance imaging and genetic testing data will be integrated into risk stratification. All patients will be asked to complete questionnaires about their symptoms; previous therapy; family history; and, at the end of the study, their experience with the ECG patch-based monitoring.

RESULTS

The Hypertrophic Cardiomyopathy: Clinical Impact of a Prolonged mHealth-Based Arrhythmia Monitoring by Single-Channel ECG (HCM-PATCH) study investigates the prevalence of nonsustained ventricular tachycardia (ie, ≥3 consecutive ventricular beats at a rate of 120 beats per minute, lasting for <30 seconds) in low- to intermediate-risk patients with HCM (according to the HCM Risk-SCD calculator) with additional mHealth-based prolonged rhythm monitoring. The study was funded by third-party funding from the Department of Cardiology and Intensive Care Medicine, University Hospital Ostwestfalen-Lippe of Bielefeld University in June 2023 and approved by the institutional review board in May 2023. Data collection began in June 2023, and we plan to end the study in February 2024. Of the 34 patients, 26 have been recruited. Data analysis has not yet taken place. Publication of the results is planned for the fall of 2024.

CONCLUSIONS

Prolonged mHealth-based rhythm monitoring could lead to differences in the prevalence of arrhythmias compared to 24- and 48-hour long-term ECGs. This may lead to improved identification of patients at high risk and trigger therapeutic interventions that may provide better protection from SCD or atrial fibrillation-related complications such as embolic stroke.

TRIAL REGISTRATION

Deutsches Register Klinischer Studien DRKS00032144; https://tinyurl.com/498bkrx8.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/52035.

Evolving Contemporary Management of Atrial Fibrillation in Hypertrophic Cardiomyopathy

Atrial fibrillation (AF) is the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM) with clinical and subclinical episodes occurring in nearly one-half of patients. AF in HCM historically has been characterized as a decisive disease complication associated with substantial risk for thromboembolic stroke and increased morbidity and mortality. However, there have been many advances in treatment strategy resulting in improved outcomes for this patient group. For example, stroke risk in HCM has been greatly reduced by using systemic oral anticoagulation initiated after the first clinical (symptomatic) AF episode, usually with preference given to direct anticoagulants over warfarin. In contrast, stroke risk scoring systems (such as CHA2DS2-VASc score) are not informative in HCM given the substantial potential for stroke events in patients with low scores, and therefore should not be used for anticoagulation decisions in this disease. A novel risk score specifically designed for HCM (HCM-AF score) can reliably identify most patients with HCM at risk for future AF. Although a strategy focused on controlling ventricular rate is effective in asymptomatic (or minimally symptomatic) patients with AF, restoring and maintaining sinus rhythm is required for most patients with marked AF symptom burden and impaired quality of life. Several antiarrhythmic drugs such as sotalol, disopyramide, and amiodarone, can be effective in suppressing AF episodes; albeit safe, long-term efficacy is supported by only limited data. Catheter AF ablation has emerged as an important treatment option for some patients, although freedom from AF after a single ablation is relatively low (35% at 3 years), multiple ablations and the concomitant use of antiarrhythmic drugs can control AF with more than two-thirds of patients maintaining sinus rhythm at 5 years. Surgical AF ablation with biatrial Cox-Maze IV performed as an adjunctive procedure during myectomy can reduce symptomatic AF episodes (70% of patients free from AF at 5 years). For the vast majority of patients who have HCM with AF, the implementation of contemporary therapies has allowed for improved quality of life and low HCM-related mortality.

An unmet need: arrhythmia detection by implantable loop recorder in the systemic right ventricle

AIMS

Patients with systemic right ventricles are at high risk of sudden cardiac death. Arrhythmia is a significant risk factor. Routine Holter monitoring is opportunistic with poor adherence. The aim of this study was to determine if continuous rhythm monitoring with an implantable loop recorder (ILR) could allow early detection of clinically important arrhythmias.

METHODS AND RESULTS

Implantable loop recorder implantation was offered to patients with atrial switch repair for transposition of the great arteries. Recordings were made with symptoms or, automatically for pauses, significant bradycardia or tachycardia and reviewed by the multi-disciplinary team. Twenty-four out of 36 eligible patients underwent ILR implantation with no complication. Forty-two per cent had preserved ventricular function, 75% were NYHA functional class I, 88% had low sudden cardiac death risk, 33% had previous intra-atrial re-entrant tachycardia (IART), and none had known conduction disease. Eighteen out of 24 (75%) patients made 52 recordings (52% automated) over 39.5 months (1.6-72.5). Thirty-two out of 52 (62%) recordings in 15/24 (63%) of the cohort were clinically significant and included sinus node disease (two patients), atrioventricular block (two patients), IART (seven patients), and IART with sinus node disease or atrioventricular block (four patients). Implantable loop recorder recordings prompted medication change in 11 patients [beta-blockers (n = 9), anti-coagulation (n = 5), and stopping anti-coagulation (n = 1)] and device therapy recommendation in seven patients [five pacemakers (three: atrioventricular block) and two defibrillators]. Two patients declined intervention; one suffered an arrhythmic death. Intra-atrial re-entrant tachycardia and clinically relevant conduction disease were detected in patients irrespective of sudden cardiac death risk.

CONCLUSION

Continuous monitoring with an ILR in patients with systemic right ventricle following atrial switch detects clinically relevant arrhythmias that impact decision-making. In this cohort, clinically relevant arrhythmias did not correlate with sudden cardiac death risk.

Art and science of risk stratification of sudden cardiac death in hypertrophic cardiomyopathy: Current state, unknowns, and future directions

The progress in the management of hypertrophic cardiomyopathy (HCM) over the last several decades has resulted in great improvements in quality of life and overall survival for HCM patients. Yet, sudden cardiac death (SCD) due to ventricular tachyarrhythmias is among the common causes of HCM-related mortality. SCD risk stratification is a central and often challenging domain in the care of the HCM patient. Distinguishing the individuals most likely to benefit from a primary prevention implantable-cardioverter defibrillator (ICD) from those truly at a low risk of SCD in whom an ICD is not necessary is a nuanced process. Clinicians need to carefully balance the potential benefit and risks of ICDs, particularly in young patients. Because of intense investigations in diverse HCM cohorts globally, two main approaches to SCD risk stratification in HCM have emerged, one based on major SCD risk factors and one based on a mathematically derived risk score. In this overview, we discuss the current state, latest advances and remaining unknowns about established and novel markers of risk of SCD in HCM. We also review how the risk factor- and risk score-based assessments can and should be used in conjunction to enhance rather than contradict each other in facilitating informed ICD decision-making in contemporary clinical practice.

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.

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.

Bluetooth-enabled implantable cardiac monitors and two-way smartphone communication for patients with hypertrophic cardiomyopathy

Background

Sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM) currently relies on arrhythmic burden quantification by 24 or 48-hour Holter monitoring. Whether this approach adequately captures arrhythmic burden, compared with longer-term continuous monitoring, is unclear. We sought to assess the long-term incidence of nonsustained ventricular tachycardia (NSVT) in HCM patients at low or moderate SCD risk, using implantable cardiac monitors (ICMs) paired with a novel Bluetooth-enabled 2-way communication platform.

Methods

This prospective, single-arm, observational study enrolled 33 HCM patients. Patients were implanted with an Abbott (Chicago, IL) Confirm Rx ICM and monitored using a protocolized care pathway.

Results

A total of 20 patients (60.6%) had ≥ 1 episode of NSVT recorded on the ICM, the majority of whom had previous Holter monitors that did not identify NSVT (60%, n = 12). A total of 71 episodes of NSVT were detected. Median time to first NSVT detection was 76.5 days (range: 0-553 days). A total of 19 patients underwent primary prevention implantable cardioverter defibrillator implantation during an average follow-up of 544 days (range: 42-925 days). A total of 172,112 automatic transmissions were received, and 65 (0.04%) required clinical follow-up. A total of 325 manual transmissions were received and managed. A total of 14 manual transmissions (4.3%) required follow-up, whereas 311 (95.7%) were managed solely with a text message.

Conclusions

Surveillance and reporting systems utilizing 2-way communication enabled by novel ICMs are feasible and allow remote management of patients with HCM. Prolonged monitoring with ICMs identified more patients with nonsustained arrythmias than did standard Holter monitoring. In many cases, this information impacted both SCD risk stratification and patient management.