Clinical Course and Quality of Life in High-Risk Patients With Hypertrophic Cardiomyopathy and Implantable Cardioverter-Defibrillators

A cost-effectiveness analysis of hypertrophic cardiomyopathy sudden cardiac death risk algorithms for implantable cardioverter defibrillator decision-making

AIMS

To conduct a contemporary cost-effectiveness analysis examining the use of implantable cardioverter defibrillators (ICDs) for primary prevention in patients with hypertrophic cardiomyopathy (HCM).

METHODS

A discrete-time Markov model was used to determine the cost-effectiveness of different ICD decision-making rules for implantation. Several scenarios were investigated, including the reference scenario of implantation rates according to observed real-world practice. A 12-year time horizon with an annual cycle length was used. Transition probabilities used in the model were obtained using Bayesian analysis. The study has been reported according to the Consolidated Health Economic Evaluation Reporting Standards checklist.

RESULTS

Using a 5-year SCD risk threshold of 6% was cheaper than current practice and has marginally better total quality adjusted life years (QALYs). This is the most cost-effective of the options considered, with an incremental cost-effectiveness ratio of £834 per QALY. Sensitivity analyses highlighted that this decision is largely driven by what health-related quality of life (HRQL) is attributed to ICD patients and time horizon.

CONCLUSION

We present a timely new perspective on HCM-ICD cost-effectiveness, using methods reflecting real-world practice. While we have shown that a 6% 5-year SCD risk cut-off provides the best cohort stratification to aid ICD decision-making, this will also be influenced by the particular values of costs and HRQL for subgroups or at a local level. The process of explicitly demonstrating the main factors, which drive conclusions from such an analysis will help to inform shared decision-making in this complex area for all stakeholders concerned.

Clinical characteristics and prognosis of patients with hypertrophic cardiomyopathy and heart failure with preserved ejection fraction

BACKGROUND

Whether heart failure with preserved ejection fraction (HFpEF) is associated with an increased risk of developing systolic dysfunction and a poor prognosis in hypertrophic cardiomyopathy (HCM) patients is unknown.

OBJECTIVE

We aimed to assess risk factors for the development of end-stage (ES) heart failure (HF) (ejection fraction < 50%) and compare the prognosis of different HF phenotypes.

METHODS

This retrospective study was conducted on patients with HCM in China between January 2009 and February 2023. Patients were stratified into three different groups: HCM-non-HF, HCM-HFpEF and HCM-heart failure with reduced ejection fraction (HCM-HFrEF). The primary outcome was a composite of major adverse cardiac events (MACEs), including all-cause deaths, HF hospitalization, sudden cardiac death and ventricular tachycardia.

RESULTS

Of 3,620 HCM patients enrolled, 1,553 (42.9%) had non-HF, 1,666 (46.0%) had HFpEF, and 579 patients (11.1%) had HFrEF at baseline. During the median follow-up period of 4.0 years (IQR 1.4-9.4 years), patients with HCM-HFpEF exhibited a higher incidence of ES-HF than those with HCM-non-HF (12.4% vs. 2.7%, P < 0.001). HFpEF was an independent risk factor for ES-HF development (HR 3.84, 2.54-5.80, P < 0.001). MACEs occurred in 26.9% with a higher incidence in HCM-HFpEF than HCM-non-HF (36.6% vs 12.2%, P < 0.001). HFpEF was an independent predictor of MACEs (HR 2.13, 1.75-2.59, P < 0.001).

CONCLUSIONS

HFpEF is common in HCM. Compared to non-HF, it increases the risk of LVEF decline and poor prognosis. It may aid in risk stratification and need close echocardiography follow-up.

Advances in the Management of Hypertrophic Cardiomyopathy Leading to Low Disease-Related Mortality in 2023

Hypertrophic cardiomyopathy (HCM) is a relatively common often inherited heart disease encumbered throughout much of its almost 60-year history by the expectation of an unfavorable outcome with shortened longevity. However, it is notable that in 2023, most patients affected with HCM can now achieve normal or extended life expectancy without major disability because of a comprehensive constellation of management strategies that have evolved largely over the last 20 years. Distinct adverse disease pathways dictate high-benefit low-risk personalized treatments, without reliance on genomics and sarcomere mutations, including: primary prevention implantable defibrillators for sudden cardiac death prevention, surgical myectomy and percutaneous alcohol septal ablation to reverse heart failure symptoms, anticoagulation to prevent embolic stroke associated with concomitant atrial fibrillation, external defibrillation and hypothermia for out-of-hospital cardiac arrest, and heart transplant in a small patient subgroup with end-stage disease. Large cohort studies using these contemporary management strategies achieved remarkably low HCM-related mortality (0.5%/year) across all age groups, which is lower than in the other cardiac or noncardiac risks of living, and largely confined to nonobstructive patients with progressive heart failure, including those awaiting heart transplant.

The Paradigm of Sudden Death Prevention in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a relatively common and, often, inherited cardiac disease, once regarded as largely untreatable with ominous prognosis and, perhaps, most visibly as a common cause of sudden cardiac death (SCD) in the young. However, HCM is now more accurately considered a treatable disease with management options that significantly alter its clinical course. This is particularly true for SCD because the penetration of implantable cardioverter-defibrillators into HCM practice enables primary prevention device therapy that reliably terminates potentially lethal ventricular tachyarrhythmias (3% to 4%/year). This therapeutic advance is largely responsible for >10-fold decrease in the overall disease-related mortality to 0.5%/year, independent of patient age. A guideline-based clinical risk stratification algorithm has evolved, which included variables identifiable with cardiac magnetic resonance: ≥1 risk markers judged major within the clinical profile of an individual patient, associated with a measure of physician judgment and shared decision-making, can be sufficient to consider the recommendation of a prophylactic defibrillator implant. Implantable cardioverter-defibrillator decisions using the American College of Cardiology and the American Heart Association traditional major risk marker strategy are associated with a 95% sensitivity for identifying those patients who subsequently experience appropriate therapy, albeit often 5 to 10+ years after implant but without heart failure deterioration or death after a device intervention. A mathematical SCD risk score proposed by European Society of Cardiology is associated with a relatively low sensitivity (33%) for predicting and preventing SCD events but with potential for less device overtreatment.

High-risk imaging characteristics in left ventricular apex for the life-threatening arrhythmic events in Japanese hypertrophic cardiomyopathy patients

Left ventricular (LV) apical aneurysm is known to be associated with the life-threatening arrhythmic events in hypertrophic cardiomyopathy (HCM). However, the current 2014 ESC guideline has not included apical aneurysm as a major risk factor for sudden cardiac death and 2018 JCS guideline includes it only as a modulator, while it has been included as a new major risk marker in 2020 AHA/ACC guideline. Therefore, we sought to identify high-risk imaging characteristics in LV apex which is associated with a higher occurrence of ventricular tachycardia/fibrillation (VT/VF). In 99 consecutive Japanese HCM patients (median age, 65 years; 59 males) undergoing implantable cardioverter-defibrillator (ICD) implantation for primary prevention following cardiac magnetic resonance including late gadolinium enhancement (LGE), the occurrence of appropriate ICD interventions for VT/VF was evaluated for 6.2 (median) years after ICD implantation. Overall, appropriate ICD interventions occurred in 43% with annual rates of 7.0% for appropriate interventions. Kaplan-Meier analysis demonstrated that the presence of LV apical aneurysm was significantly associated with a higher occurrence of appropriate interventions (annual rates 18.9% vs. 6.4%, P = 0.013). Similarly, patients with high LV mid-to-apex pressure gradient (annual rates 14.9% vs. 6.2%, P = 0.022) and presence of apical LGE (annual rates 10.9% vs. 4.0%, P = 0.001) experienced appropriate interventions more frequently. An aneurysm, high-pressure gradient, and LGE in an apex are associated with VT/VF. These characteristics in apex should be kept in mind when implanting ICD in Japanese HCM patients as a primary prevention.

Clinical course of hypertrophic cardiomyopathy patients implanted with a transvenous or subcutaneous defibrillator

AIMS

The implantable cardioverter-defibrillator (ICD) is a life-saving therapy in patients with hypertrophic cardiomyopathy (HCM) at risk of sudden cardiac death. Implantable cardioverter-defibrillator complications are of concern. The subcutaneous ICD (S-ICD) does not use transvenous leads and is expected to reduce complications. However, it does not provide bradycardia and anti-tachycardia pacing (ATP). The aim of this study was to compare appropriate and inappropriate ICD interventions, complications, disease-related adverse events and mortality between HCM patients implanted with a S- or transvenous (TV)-ICD.

METHODS AND RESULTS

Consecutive HCM patients implanted with a S- (n = 216) or TV-ICD (n = 211) were enrolled. Propensity-adjusted cumulative Kaplan-Meier curves and multivariate Cox proportional hazard ratios were used to compare 5-year event-free survival and the risk of events. The S-ICD patients had lower 5-year risk of appropriate (HR: 0.32; 95%CI: 0.15-0.65; P = 0.002) and inappropriate (HR: 0.44; 95%CI: 0.20-0.95; P = 0.038) ICD interventions, driven by a high incidence of ATP therapy in the TV-ICD group. The S- and TV-ICD patients experienced similar 5-year rate of device-related complications, albeit the risk of major lead-related complications was lower in S-ICD patients (HR: 0.17; 95%CI: 0.038-0.79; P = 0.023). The TV- and S-ICD patients displayed similar risk of disease-related complications (HR: 0.64; 95%CI: 0.27-1.52; P = 0.309) and mortality (HR: 0.74; 95%CI: 0.29-1.87; P = 0.521).

CONCLUSION

Hypertrophic cardiomyopathy patients implanted with a S-ICD had lower 5-year risk of appropriate and inappropriate ICD therapies as well as of major lead-related complications as compared to those implanted with a TV-ICD. Long-term comparative follow-up studies will clarify whether the lower incidence of major lead-related complications will translate into a morbidity or survival benefit.

Analysis of risk stratification and prevention of sudden death in pediatric patients with hypertrophic cardiomyopathy: Dilemmas and clarity

Hypertrophic cardiomyopathy (HCM) has been considered the most common cause of sudden death (SD) in the young. However, introduction of implantable cardioverter-defibrillators (ICDs) in HCM has proved highly effective and the mainstay of preventing SD in children, adolescents, and adults by terminating malignant ventricular tachyarrhythmias. Nevertheless, ICD decision making is generally regarded as more difficult in pediatrics, and the strategy for selecting ICD patients from this population remains without consensus. Prospective studies in HCM children and adolescents have shown the American Heart Association/American College of Cardiology traditional major risk marker strategy to be reliable with >90% sensitivity in selecting patients for SD prevention. International data in >2000 young HCM patients assembled over 20 years who were stratified by major risk markers showed ICDs effectively prevented SD in 20%. Alternatively, novel quantitative risk scoring initiatives provide 5-year risk estimates that are potentially useful as adjunctive tools to facilitate discussion of prophylactic ICD risks vs benefit but are as yet unsupported by prospective outcome studies. Risk scoring strategies are characterized by reasonable discriminatory statistical power (C-statistic 0.69-0.76) for identifying patients with SD events but with relatively low sensitivity, albeit with specificity comparable with the risk marker strategy. While some reticence for obligating healthy-appearing young patients to lifelong device implants is understandable, underutilization of the ICD in high-risk children and adolescents can represent a lost opportunity for fulfilling the long-standing aspiration of SD prevention. This review provides a critical assessment of the current strengths and weaknesses of SD risk stratification strategies in young HCM patients in an effort to clarify clinical decision making in this challenging subpopulation.

Development of the Implantable Cardioverter-Defibrillator: JACC Historical Breakthroughs in Perspective

Implantable cardioverter-defibrillators (ICDs) represent transformational technology, arguably the most significant advance in cardiovascular medicine in 50 years. The vision and determination of pioneers Mirowski and Mower was fundamental to this monumental achievement, working with limited resources and confronted by skepticism/criticism from medical establishment. The inventors were followed >35 years in which a multitude of innovative clinical scientists and engineers introduced technological advances leading to the sophisticated devices in practice today. A pivotal patient experiment with automated termination of ventricular fibrillation (1980) led to U.S. Food and Drug Administration approval. Transvenous lead systems converted ICDs from thoracotomy-based secondary prevention to primary prevention of sudden death devices in countless patients worldwide. ICD acceptance was solidified by prospective randomized controlled trials showing reduced mortality superior to antiarrhythmic drugs. ICDs eventually expanded from coronary disease to inherited arrhythmia conditions (eg, hypertrophic cardiomyopathy). The ICD breakthrough story demonstrates how significant progress is possible in medicine against all odds, given fearless imagination to pursue novel ideas that conflict with accepted wisdom.

Differing strategies for sudden death prevention in hypertrophic cardiomyopathy

Sudden death (SD) has traditionally been the most visible and feared complication of hypertrophic cardiomyopathy (HCM). Substantial progress in reducing the occurrence of these catastrophic events represents a new paradigm in disease management. Prevention of SD in HCM has resulted from introduction of primary prevention ICDs that reliably terminate life-threatening ventricular tachyarrhythmias, as well as a matured risk stratification algorithm capable of reliably identifying those patients at highest risk. This initiative has been a major determinant of reducing HCM-related mortality to a low rate of 0.5%/year. In such a heterogeneous heart disease as HCM, no perfect risk stratification strategy is possible, and available approaches differ in terms of sensitivity and specificity for identifying patients with SD risk. Major cardiovascular societies, American Heart Association/American College of Cardiology in the USA and European Society of Cardiology in Europe have promoted different risk stratification guidelines creating the potential for judging SD risk in a given HCM patient differently based on commitment to a particular societal guideline or country of residence. In this review, we provide a critical but balanced assessment of these two divergent SD prevention strategies with regard to their respective strengths and weaknesses, as a guide to clinicians directly engaged in this important management issue.

Opportunities and drawbacks of the subcutaneous defibrillator across different clinical settings

INTRODUCTION

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an established therapy for the prevention of sudden cardiac death (SCD) and an alternative to a transvenous implantable cardioverter-defibrillator system in selected patients. Beyond randomized clinical trials, many observational studies have described the clinical performance of S-ICD across different subgroups of patients.

AREAS COVERED

Our review aimed to describe the opportunities and drawbacks of the S-ICD, focusing on their use in special populations and across different clinical settings.

EXPERT OPINION

The choice to implant S-ICD should be based on the patient's tailored approach, which takes into account the adequate S-ICD screening at rest or during stress, the infective risk, the ventricular arrhythmia susceptibility, the progressive nature of the underlying disease, the work or sports activity, and the risk of lead-related complications.

Effect of Obesity on Left Ventricular Remodeling and Clinical Outcome in Chinese Patients With Hypertrophic Cardiomyopathy: Assessed by Cardiac MRI

BACKGROUND

Obesity is highly prevalent in patients with hypertrophic cardiomyopathy (HCM) and believed to influence its phenotype.

PURPOSE

To explore the effects of obesity on left ventricular (LV) remodeling and long-term clinical course in Chinese patients with HCM.

STUDY TYPE

Longitudinal.

POPULATION

A total of 247 patients with HCM classified according to body mass index (BMI) (normal weight: BMI = 18.0-22.9 kg/m² [N = 90]; overweight: BMI = 23.0-24.9 kg/m² [N = 58]; and obese: BMI ≥ 25 kg/m² [N = 99]).

FIELD STRENGTH/SEQUENCE

3.0 T/Balanced steady-state free precession sequence and phase-sensitive inversion recovery late gadolinium enhancement (LGE) sequence.

ASSESSMENT

LV function and geometry were measured. LV peak strain analysis was performed. The presence and percentage of LGE in the LV were recorded. The endpoints including heart failure, sudden cardiac death, and overall composite outcome were assessed during a median follow-up of 4.1 years (interquartile range, 3.0-6.2 years).

STATISTICAL TESTS

One-way analysis of variance, Kruskal-Wallis test, or chi-square test; Pearson correlation coefficient (r); multivariable linear regression analysis; Kaplan-Meier survival analysis; and Cox proportional hazards model analysis were conducted. A two-tailed P-value < 0.05 was considered statistically significant.

RESULTS

Obese patients exhibited a significant progressive increase in LV mass compared with normal-weight patients. The magnitude of all LV strain indices gradually and significantly decreased as BMI increased, whereas LV ejection fraction was not significantly different among BMI groups (P = 0.364). Multivariable linear regression analysis showed that obesity had a significant association with impaired strain indices as well as with indexed LV mass. Multivariable Cox model analysis retained obesity as an independent marker for future endpoints, and conveyed a > 3-fold increase in risk compared with patients with normal weight (hazard ratio, 3.04; 95% confidence interval, 1.07-6.57).

DATA CONCLUSION

Obesity is an important environmental modifier that is associated with adverse LV remodeling and is independently associated with future clinical outcomes in Chinese patients with HCM.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Quality of life and physical functioning in black and white adults with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a common and clinically heterogeneous inherited cardiac disease. Quality of life (QOL) and physical functioning are important clinically but are underexplored in diverse populations with HCM.

OBJECTIVES

To examine predictors for and compare QOL and physical functioning in Black and White adults with HCM.

METHODS

We analyzed a sub-sample from a longitudinal prospective study on HCM. Eligibility criteria included self-identified Black and White adults (≥18 years) with clinical HCM. QOL was measured with the Minnesota Living with Heart Failure Questionnaire (MLWHF);physical functioning included age-adjusted exercise capacity and NYHA class. Covariates included HCM structural characteristics and common comorbidities. We analyzed data from 434 individuals, 57 (13.1%) of whom self-identified as Black/African American.

RESULTS

In this sample, the Black cohort had higher MLWHF scores, 31.2 (27.2) v. 23.9 (22.1), p=0.042, signifying worse QOL, but there were no intergroup differences when QOL was dichotomized. Mean metabolic equivalents (METs) on symptom-limited stress testing were similar, though the Black cohort was younger, 54.6 (13.4) v.62.5 (14.8) years, p=0.001. No one from the Black cohort achieved an "excellent-for-age" exercise capacity, and 64.1% had a "below-average-for-age" exercise capacity vs 47% in the White cohort, though this was not statistically significant, p=0.058. There was no difference between groups in advanced NYHA class. Female gender was associated with worse QOL and physical functioning irrespective of covariates.

CONCLUSIONS

This study is a starting point that underscores the need for a more comprehensive examination of well-being and physical functioning in Black populations with HCM.

Relation of delayed intrinsicoid deflection of the QRS complex to sudden cardiac death in patients with hypertrophic cardiomyopathy

AIMS

Predictors of sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM) do not include ECG variables. Intrinsicoid deflection (ID) represents the early ventricular depolarization on surface ECG. Delayed ID (DID) has been associated with sudden cardiac arrest (SCA) in the community. In a cohort of consecutive patients with HCM, we assessed whether DID predicts SCA or its surrogates.

METHODS

We reviewed ECG, clinical and follow-up data of 344 consecutive HCM patients. DID (ID ≥50 ms) was classified as lateral (leads I or aVL), inferior (leads II, III or aVF), and precordial (leads V5 or V6). The endpoint was a combination of SCD, resuscitated SCA or appropriate ICD intervention.

RESULTS

The SCA group was composed by 2 secondary prevention ICD recipients and 23 patients that reached the endpoint during follow-up (108 ± 73 months). SCA patients had more frequently massive LV hypertrophy (LVH) or end-stage HCM. ECG indexes of LVH were comparable between SCA and controls. SCA patients were more likely to have DID on ECG lateral leads I/aVL (72% vs 44%; p = 0.008). A non significant trend was observed for inferior and V5/V6 leads. DID I/aVL was associated with SCA in multivariate analysis after correction for massive LVH and end-stage disease (HR: 2.86; 95%CI: 1.14-7.13; p = 0.02).

CONCLUSIONS

In HCM patients DID is associated with increased risk of SCA. Its prognostic value extends beyond that of LVH. If confirmed in prospective studies, the prognostic power of this ECG marker could be used to refine risk prediction.

Sex and Race Disparities in Hypertrophic Cardiomyopathy: Unequal Implantable Cardioverter-Defibrillator Use During Hospitalization

OBJECTIVE

To evaluate if there are sex and race disparities in use of implantable cardioverter-defibrillator (ICD) devices for prevention of sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM).

PATIENTS AND METHODS

Using the National Inpatient Sample from January 2003 through December 2014, we identified all adult admissions with a diagnosis of HCM and an ICD implantation. Race was classified as White versus non-White. Trends in ICD use, predictors of ICD implantation, device-related complications, hospitalization costs, and lengths of stay were evaluated.

RESULTS

Among a total of 23,535 adult hospitalizations for HCM, ICD implantation was performed in 3954 (16.8%) admissions. Over the study period, there was an overall increasing trend in ICD use (11.6% in 2003 to 17.0% in 2014, P<.001). Compared with admissions not receiving an ICD, those receiving an ICD had shorter median lengths of in-hospital stay but higher hospitalization costs (P<.001). Compared with men and White race, female sex (odds ratio, 0.72; 95% CI, 0.66 to 0.78; P<.001) and non-White race (odds ratio, 0.87; 95% CI, 0.79 to 0.96; P<.001) were associated with lower adjusted odds of receiving an ICD. Women and non-White hospitalizations had higher rates of device related complications, longer lengths of in-hospital stay, and higher hospitalization costs compared with men and White race, respectively (all P<.01).

CONCLUSION

Among HCM hospitalizations, ICD devices are underused in women and racial minorities independent of demographics, hospital characteristics, and comorbidities. Women and racial minorities also had higher rates of complications and greater resource use compared with men and those belonging to the White race, respectively.

The friend within? The implantable cardioverter defibrillator between saving lives and chronically impairing them

This article considers the way in which a medical technology, the implantable cardioverter defibrillator (ICD), by preventing fatal outcomes, in this case sudden death, deriving from cardiac diseases, and specifically hypertrophic cardiomyopathy, contributes to the development of a particular type of chronicity. While biomedicine celebrates technological advances in treatments and naturalises chronicity, focussing on life expectancy as a victory over the 'acute' aspects of the disease, the way in which patients live with the disease is left unquestioned. The article follows Smith-Morris's (2010) perspective in seeing chronicity as the never-ending process of identifying with one's disease, adding a focus on the role played by an embodied technology in relation to it. Based on participant observation in a clinical setting and interviews with clinicians, the article interrogates three key themes in the chronicity of cardiac patients implanted with an ICD: risk, quality of life and choice. The data shows a constant tension between managing a one-off potentially fatal 'acute' risk and life with serious disruptions due to the limitations imposed by the implanted device. The article argues that patients' resources for facing the life and identity disrupted by the disease are limited by ideas of what living a diseased body is, which acritically follow discourses of 'patient choice' and a 'technological imperative' to avoid risk.

A Prospective Longitudinal Study of Health-Related Quality of Life and Psychological Wellbeing after an Implantable Cardioverter Defibrillator in Patients with Genetic Heart Diseases

Background

Genetic heart diseases (GHDs) can be clinically heterogeneous and pose an increased risk of sudden cardiac death (SCD). The implantable cardioverter-defibrillator (ICD) is a lifesaving therapy. Impacts on prospective and long-term psychological and health-related quality of life (HR-QoL) after ICD implant in patients with GHDs are unknown.

Objectives

Investigate the psychological functioning and HR-QoL over time in patients with GHDs who receive an ICD, and identify risk factors for poor psychological functioning and HR-QoL.

Methods

A longitudinal, prospective study design was used. Patients attending a specialized clinic, diagnosed with a GHD for which they received an ICD between May 2012 and January 2015, were eligible. Baseline surveys were completed prior to ICD implantation with 5-year follow-up after ICD implant. We measured psychological functioning (Hospital Anxiety Depression Scale, Florida Shock Anxiety Scale), HR-QoL (Short-Form 36v2), and device acceptance (Florida Patient Acceptance Scale).

Results

Forty patients were included (mean age 46.3 ± 14.2 years; 65.0% male). Mean psychological and HR-QoL measures were within normative ranges during follow-up. After 12 months, 33.3% and 19.4% of participants showed clinically elevated levels of anxiety and depression, respectively. Longitudinal mixed-effect analysis showed significant improvements from baseline to first follow-up for the overall cohort, with variability increasing after 36 months. Nontertiary education and female sex predicted worse mental HR-QoL and anxiety over time, while comorbidities predicted depression and worse physical HR-QoL.

Conclusion

While the majority of patients with a GHD adjust well to their ICD implant, a subset of patients experience poor psychological and HR-QoL outcomes.

Hypertrophic Cardiomyopathy: New Concepts and Therapies

Hypertrophic cardiomyopathy (HCM), a relatively common, globally distributed, and often inherited myocardial disorder, transformed over the last several years into a treatable condition with the emergence of effective management options that alter natural history at all ages. Now available are a matured risk stratification algorithm selecting patients for prophylactic implantable defibrillators that prevent arrhythmic sudden death; low-risk, high-benefit surgical myectomy to reverse progressive heart failure symptoms due to left ventricular outflow obstruction; anticoagulation prophylaxis to prevent atrial fibrillation-mediated embolic stroke; and heart transplant for refractory end-stage disease in the absence of obstruction. Those strategies have resulted in reduction of HCM-related morbidity and reduction of mortality to 0.5% per year.

Hypertrophic Cardiomyopathy in the Elderly: A Case Identified With Genetic Screening

Hypertrophic cardiomyopathy (HCM) is a hereditary disease with an autosomal dominant pattern of inheritance, that is caused by a mutation in one of several sarcomere genes that encodes components of the contractile system of the heart. Hypertrophic cardiomyopathy has been described as a disease that is more heavily diagnosed in the second decade of life, that may present with abnormal syncopal episodes or sudden cardiac death. However, with a better understanding of the genetic changes that occur in HCM and with improved imaging techniques, there has now been an increased recognition of a late-onset disease that can occur in the elderly population. We report a case of a 73-year-old woman who was found to have HCM after various clinical events took place.

The Arrhythmic Phenotype in Cardiomyopathy

In the wide phenotypic spectrum of cardiomyopathies, sudden cardiac death (SCD) has always been the most visible and devastating disease complication. The introduction of implantable cardioverter-defibrillators for SCD prevention by the late 1980s has moved the question from how to whom we should protect from SCD, leaving clinicians with a measure of uncertainty regarding the most reliable option to guide identification of the highest-risk patients. In this review, we will go through all the available evidence in the field of arrhythmic expression and arrhythmic risk stratification in the different phenotypes of cardiomyopathies to provide practical suggestions in daily clinical management.

Implantable cardioverter-defibrillators for hypertrophic cardiomyopathy: The Times They Are a-Changin'

The implantable cardioverter-defibrillator (ICD) is a life-saving therapy in patients with hypertrophic cardiomyopathy (HCM) at high risk of sudden cardiac death. The heterogeneity of clinical scenarios in HCM and the availability of ICDs with distinct characteristics emphasizes the need for selecting the right device for the right patient. There is growing awareness that unnecessarily complex devices can lead to short- and long-term complications without adding significant clinical benefits. Young patients have the greatest potential years of life gained from the ICD but are also most exposed to device-related complications. This increases the complexity of decision-making of ICD prescription in these often otherwise well patients in whom device selection should be tailored to preserve survival benefit without introducing morbidity. In the light of the multiple clinical phenotypes characterizing HCM, the present article offers evidence-based perspectives helpful in predicting the individual impact of the ICD and choosing the most appropriate device.

Prognostic implications of different clinical profiles in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a myocardial genetic disease relatively common in the general population with heterogenous clinical presentation, natural history and prognosis. About 60% of HCM patients have a stable clinical course, while others may experience a variety of HCMrelated complications which follows relatively independent pathways, and that can be distinguished in different subgroups. These subgroups are represented by patients with left ventricular outflow tract obstruction; patients with end-stage disease and reduced or preserved systolic function; patients with apical hypertrophy; patients with apical aneurysm; patients with atrial fibrillation, patients at high risk of sudden death and patients with pre-clinical HCM. The purpose of this review is to describe each of these clinical profiles with its prognostic implications.

Cardiovascular Diseases That Have Emerged From the Darkness

It is important for both the patient and physician communities to have timely access to information recognizing rapid progress in the diagnosis and treatment of familiar but relatively uncommon cardiovascular diseases. Patients with 3 cardiovascular diseases (ie, hypertrophic cardiomyopathy, pulmonary arterial hypertension, and transthyretin (TTR) cardiac amyloidosis (ATTR)]), once considered rare without effective management options and associated with malignant prognosis, have now benefited substantially from the development of a variety of innovative therapeutic strategies. In addition, in each case, enhanced diagnostic testing has expanded the patient population and allowed for more widespread administration of contemporary treatments. In hypertrophic cardiomyopathy, introduction of implantable defibrillators to prevent sudden death as well as high-benefit:low-risk septal reduction therapies to reverse heart failure have substantially reduced morbidity and disease-related mortality (to 0.5% per year). For pulmonary arterial hypertension, a disease once characterized by a particularly grim prognosis, prospective randomized drug trials with aggressive single (or combined) pharmacotherapy have measurably improved survival and quality of life for many patients. In cardiac amyloidosis, development of disease-specific drugs can for the first time reduce morbidity and mortality, prominently with breakthrough ATTR-protein-stabilizing tafamidis. In conclusion, in less common and visible cardiovascular diseases, it is crucial to recognize substantial progress and achievement, given that penetration of such information into clinical practice and the patient community can be inconsistent. Diseases such as hypertrophic cardiomyopathy, pulmonary arterial hypertension, and ATTR cardiac amyloidosis, once linked to a uniformly adverse prognosis, are now associated with the opportunity for patients to experience satisfactory quality of life and extended longevity.

Hypertrophic cardiomyopathies requiring more monitoring for less atrial fibrillation-related complications: a clustering analysis based on the French registry on hypertrophic cardiomyopathy (REMY)

AIMS

Defining the risk of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) patients is an important clinical and prognostic challenge. The aim of this study is to determine HCM phenogroups with different risk of AF occurrence at 5 years.

METHODS AND RESULTS

We applied retrospectively the Bayesian method, which can analyze a large number of variables, to differentiate phenogroups of patients with different risks of AF and prognoses across a French prospective on-going hospital-based registry of adult HCM patients (REMY). Clinical and imaging data were prospectively recorded, and patients were followed for 5 years. A total of 1431 HCM patients were recruited, including 1275 analyzed in the present study after exclusion criteria. The population included 412 women, 369 patients with obstructive HCM, and 252 implanted with an ICD. AF occurred in 167 (11.6%) patients during the 5 year follow-up. Three phenogroups were defined according to their common clinical and echocardiographic characteristics. Patients at the highest risk were oldest, more often female, with more frequent comorbidities, anteroposterior diameter of the left atrium was significantly greater, with diastolic dysfunction, outflow-tract obstruction, and mitral valve abnormality, and presented higher pulmonary artery pressure and/or right-ventricular dysfunction. These also had a higher risk of all-cause hospitalizations and death.

CONCLUSION

Based on a clustering analysis, three phenogroups of HCM according to the risk of AF occurrence can be identified. It can indicate which patients should be more monitored and/or treated, particular to prevent the risk of stroke.

Evolution of risk stratification and sudden death prevention in hypertrophic cardiomyopathy: Twenty years with the implantable cardioverter-defibrillator

Hypertrophic cardiomyopathy (HCM) is a relatively common inherited myocardial disorder, once regarded as largely untreatable with ominous prognosis and most visibly as a common cause of sudden death (SD) in the young. Over the last several years, HCM has been transformed into a contemporary treatable disease with management options that significantly alter clinical course. With the use of implantable cardioverter-defibrillators (ICDs) in the HCM patient population, a new paradigm has emerged, with primary prevention device therapy reliably terminating potentially lethal ventricular tachyarrhythmias (3%-4% per year) and being largely responsible for a >10-fold decrease in disease-related mortality (to 0.5% per year), independent of age. An evidenced-based and guideline directed clinical risk stratification algorithm has evolved, including variables identified with cardiac magnetic resonance. One or more risk markers judged major and relevant within a patient's clinical profile can be considered sufficient to recommend a primary prevention implant (associated with a measure of physician judgment and shared decision-making). ICD decisions using the prospective individual risk marker strategy have been associated with 95% sensitivity for identifying patients who subsequently experienced appropriate ICD therapy, (albeit often delayed substantially for >5 or >10 years after implant), but without heart failure deterioration or HCM death following device intervention. A rigid mathematically derived statistical risk model proposed by the European Society of Cardiology is associated with low sensitivity (ie, 33%) for predicting SD events. Introduction of prophylactically inserted ICDs to HCM 20 years ago has significantly altered the clinical course and landscape of this disease. SD prevention has reduced HCM mortality significantly, making preservation of life and the potential for normal longevity a reality for most patients.

Quality of life status determinants in hypertrophic cardiomyopathy as evaluated by the Kansas City Cardiomyopathy Questionnaire

Purpose

The present study evaluated how heart failure (HF) negatively impacts health-related quality of life (HRQoL) in hypertrophic cardiomyopathy (HCM) patients and explored the major clinical determinants associated with HRQoL impairment in this population.

Methods

This was a cross-sectional single-center study of health-related HRQoL that included 91 consecutive patients with HCM. Evaluation was performed based on a comprehensive protocol that included the recommended diagnostic studies, as well as administration of the translated validated version of the Kansas City Cardiomyopathy Questionnaire (KCCQ) (CV Outcomes Inc) as a health status measure.

Results

The cohort included 52 (57%) males, median age 58 (20–85) years. The median global KCCQ score was 67 (12.5–100) corresponding to a moderate impairment in HRQoL. There was an inverse correlation between the median global KCCQ score and NYHA class (Kendall’s tau b coefficient r − 0.33, p = 0.001). Patients with pulmonary hypertension (PHT), defined as resting pulmonary artery systolic pressure of ≥ 45 mmHg, presented a significantly worse HRQoL as compared to those without PHT (median KCCQ score 56.2 vs 77.5, p = 0.013). The KCCQ score mildly correlated with age (r − 0.18, p = 0.014), history of syncope (r − 0.18, p = 0.045), estimated glomerular filtration rate (eGFR) (r 0.31, p < 0.001), plasmatic creatinine (r − 0.18, p = 0.017) and urea levels (r − 0.27, p < 0.001), left ventricular (LV) end-systolic dimensions (r − 0.18, p = 0.014), maximal provoked intraventricular gradient (r 0.20, p = 0.039), LV ejection fraction (r 0.15, p = 0.04), average E/e′ (r − 0.16, p = 0.039), pulmonary acceleration time (r 0.21, p = 0.007), pulmonary artery systolic pressure (r − 0.20, p = 0.016). In ordinal regression, the independent predictors of HRQoL were NYHA class and eGFR.

Conclusions

Patients with HCM and HF present a moderate degree of alteration in HRQoL. This is especially true for patients with PHT and more severe functional impairment. Renal failure and NYHA class are potential markers of HRQoL in clinical practice.

Long-Term Outcome in High-Risk Patients With Hypertrophic Cardiomyopathy After Primary Prevention Defibrillator Implants

Background:

The implantable cardioverter-defibrillator (ICD) is effective for preventing sudden death in patients with hypertrophic cardiomyopathy. However, data on performance and complications of implanted ICDs over particularly long time periods to inform clinical practice is presently incomplete.

Methods:

The study cohort comprises 217 consecutive hypertrophic cardiomyopathy patients with primary prevention ICDs implanted before 2008 and followed for ≥10 years (mean 12±4; range to 31).

Results:

Patients were 38±17 years at implant and 45 (21%) experienced appropriate interventions terminating ventricular tachycardia/ventricular fibrillation. The majority of ICD discharges occurred ≥5 years after implant (29 patients; 64%), including ≥10 years in 16 patients (36%). Initial device therapy increased in frequency from 2.3% of patients at <1 year to 8.5% of patients at ≥10-years after implant ( P =0.005). Inappropriate ICD shocks in 39 patients occurred most commonly <5 years after implant (54%) and decreased in frequency with increasing time from implant (from 9.7% of patients at <5 years to 3.8% at ≥10 years, P =0.02). Other major device complications including infection and lead fractures and dislodgement occurred in 27 patients (12%) but did not increase in frequency over follow-up after implant ( P =0.47). There were no arrhythmic sudden death events among the 217 patients with ICD.

Conclusions:

In hypertrophic cardiomyopathy, after a primary prevention implant, ICD therapy often followed prolonged periods of device dormancy and increased progressively in frequency over time, including one-third of patients with initial therapy after 5 to 9 years, and an additional one-third of patients at ≥10 years. Frequency of inappropriate shocks decreased over follow-up, likely reflecting standard changes in device programming, while occurrence of device complications, such as lead fractures/infection, did not increase during follow-up.

Psychological Issues in Managing Families with Inherited Cardiovascular Diseases

The field of cardiovascular genetic counseling has evolved dramatically in recent years largely to manage the unique psychological needs of the inherited cardiovascular disease patient population. For many, there can be difficulty in coming to terms with a diagnosis, whether it be adjusting to lifestyle recommendations such as exclusion from competitive sports or living with a small but remarkable risk of sudden cardiac death. For those considered at risk of life-threatening ventricular arrhythmias, the decision to have an implantable cardioverter defibrillator can be difficult. Living with the device, especially for those who are young and those who receive multiple shocks, can precipitate psychological distress and poor adaptation to the device. Family members who experience a sudden cardiac death of a young relative have a significant risk of poor psychological outcomes. The roles of the cardiac genetic counselor in facilitating patients' adaptation to their diagnoses and management and recognizing when additional support from a clinical psychologist is needed are key to ensuring families receive the best possible care.

A Validated Model for Sudden Cardiac Death Risk Prediction in Pediatric Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death (SCD) in children and young adults. Our objective was to develop and validate a SCD risk prediction model in pediatric hypertrophic cardiomyopathy to guide SCD prevention strategies.

METHODS

In an international multicenter observational cohort study, phenotype-positive patients with isolated hypertrophic cardiomyopathy <18 years of age at diagnosis were eligible. The primary outcome variable was the time from diagnosis to a composite of SCD events at 5-year follow-up: SCD, resuscitated sudden cardiac arrest, and aborted SCD, that is, appropriate shock following primary prevention implantable cardioverter defibrillators. Competing risk models with cause-specific hazard regression were used to identify and quantify clinical and genetic factors associated with SCD. The cause-specific regression model was implemented using boosting, and tuned with 10 repeated 4-fold cross-validations. The final model was fitted using all data with the tuned hyperparameter value that maximizes the c-statistic, and its performance was characterized by using the c-statistic for competing risk models. The final model was validated in an independent external cohort (SHaRe [Sarcomeric Human Cardiomyopathy Registry], n=285).

RESULTS

Overall, 572 patients met eligibility criteria with 2855 patient-years of follow-up. The 5-year cumulative proportion of SCD events was 9.1% (14 SCD, 25 resuscitated sudden cardiac arrests, and 14 aborted SCD). Risk predictors included age at diagnosis, documented nonsustained ventricular tachycardia, unexplained syncope, septal diameter z-score, left ventricular posterior wall diameter z score, left atrial diameter z score, peak left ventricular outflow tract gradient, and presence of a pathogenic variant. Unlike in adults, left ventricular outflow tract gradient had an inverse association, and family history of SCD had no association with SCD. Clinical and clinical/genetic models were developed to predict 5-year freedom from SCD. Both models adequately discriminated between patients with and without SCD events with a c-statistic of 0.75 and 0.76, respectively, and demonstrated good agreement between predicted and observed events in the primary and validation cohorts (validation c-statistic 0.71 and 0.72, respectively).

CONCLUSION

Our study provides a validated SCD risk prediction model with >70% prediction accuracy and incorporates risk factors that are unique to pediatric hypertrophic cardiomyopathy. An individualized risk prediction model has the potential to improve the application of clinical practice guidelines and shared decision making for implantable cardioverter defibrillator insertion. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT0403679.

Enhanced American College of Cardiology/American Heart Association Strategy for Prevention of Sudden Cardiac Death in High-Risk Patients With Hypertrophic Cardiomyopathy

Importance

Strategies for reliable selection of high-risk patients with hypertrophic cardiomyopathy (HCM) for prevention of sudden cardiac death (SCD) with implantable cardioverter/defibrillators (ICDs) are incompletely resolved.

Objective

To assess the reliability of SCD prediction methods leading to prophylactic ICD recommendations to reduce the number of SCDs occurring in patients with HCM.

Design, Setting, and Participants

In this observational longitudinal study, 2094 predominantly adult patients with HCM consecutively evaluated over 17 years in a large HCM clinical center were studied. All patients underwent prospective ICD decision making relying on individual major risk markers derived from the HCM literature and an enhanced American College of Cardiology/American Heart Association (ACC/AHA) guidelines-based risk factor algorithm with complete clinical outcome follow-up. Data were collected from June 2017 to February 2018, and data were analyzed from February to July 2018.

Main Outcomes and Measures

Arrhythmic SCD or appropriate ICD intervention for ventricular tachycardia or ventricular fibrillation.

Results

Of the 2094 study patients, 1313 (62.7%) were male, and the mean (SD) age was 51 (17) years. Of 527 patients with primary prevention ICDs implanted based on 1 or more major risk markers, 82 (15.6%) experienced device therapy-terminated ventricular tachycardia or ventricular fibrillation episodes, which exceeded the 5 HCM-related SCDs occurring among 1567 patients without ICDs (0.3%), including 2 who declined device therapy, by 49-fold (95% CI, 20-119; P = .001). Cumulative 5-year probability of an appropriate ICD intervention was 10.5% (95% CI, 8.0-13.5). The enhanced ACC/AHA clinical risk factor strategy was highly sensitive for predicting SCD events (range, 87%-95%) but less specific for identifying patients without SCD events (78%). The C statistic calculated for enhanced ACC/AHA guidelines was 0.81 (95% CI, 0.77-0.85), demonstrating good discrimination between patients who did or did not experience an SCD event. Compared with enhanced ACC/AHA risk factors, the European Society of Cardiology risk score retrospectively applied to the study patients was much less sensitive than the ACC/AHA criteria (34% [95% CI, 22-44] vs 95% [95% CI, 89-99]), consistent with recognizing fewer high-risk patients.

Conclusions and Relevance

A systematic enhanced ACC/AHA guideline and practice-based risk factor strategy prospectively predicted SCD events in nearly all at-risk patients with HCM, resulting in prophylactically implanted ICDs that prevented many catastrophic arrhythmic events in this at-risk population.

Identification of a lncRNA-miRNA-mRNA network based on competitive endogenous RNA theory reveals functional lncRNAs in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease that affects 1 in every 200 people in the general population, leading to cardiac ischemia, heart failure and increased risk of sudden death. Recently, accumulating evidence has suggested that long noncoding RNAs (lncRNAs) may serve specific roles in various biological processes and participate in the pathology of various diseases, including HCM. Although a large number of lncRNAs have been detected, the functions of lncRNAs in HCM are still unknown. In the present study, a global triple network based on competitive endogenous RNA (ceRNA) theory was constructed using data from the National Center for Biotechnology Information Gene Expression Omnibus. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of mRNAs in the lncRNA-microRNA (miRNA)-mRNA network were performed using the Cytoscape plugins, BiNGO and Database. The lncRNA-miRNA-mRNA network was composed of 30 lncRNA nodes, 94 mRNA nodes and 8 miRNA nodes. Subsequently, hub nodes and the number of relationship pairs were analyzed and showed that 5 lncRNAs (ENST00000597346.1, ENST00000458178.1, ENST00000544461.1, ENST00000567093.1 and ENST00000571219.1) were closely related to HCM. Cluster module analysis and Random Walk with Restart of the ceRNA network further confirmed the potential role of two lncRNAs (ENST00000458178.1 and ENST00000567093.1) in HCM. The present study provides a new strategy for identifying potential pathways associated with HCM or other diseases. Furthermore, lncRNA-miRNA pairs may be regarded as candidate diagnostic biomarkers or potential therapeutic targets for HCM.

Improvement in sudden cardiac death risk prediction by the enhanced American College of Cardiology/American Heart Association strategy in Chinese patients with hypertrophic cardiomyopathy

BACKGROUND

The lack of validated and effective sudden cardiac death (SCD) risk prediction methods is the biggest barrier to perform the lifesaving treatment with a prophylactic implantable cardioverter-defibrillator in Chinese patients with hypertrophic cardiomyopathy (HCM).

OBJECTIVE

This study aimed to evaluate the efficacy of 3 existing SCD risk prediction methods recommended by the 2011 American College of Cardiology Foundation and American Heart Association (ACCF/AHA) guideline, the 2014 European Society of Cardiology (ESC) guideline, and the 2019 enhanced American College of Cardiology (ACC)/AHA strategy in Chinese patients with HCM.

METHODS

The present study consisted of 1369 consecutive adult patients with HCM without a history of SCD events. The primary end point was a composite of SCD and equivalent events, namely, resuscitation from cardiac arrest and appropriate implantable cardioverter-defibrillator shock therapy for ventricular tachycardia or fibrillation.

RESULTS

During follow-up of 3.2 ± 2.4 years, 39 patients reached SCD end points, of whom 26 (66.7%) were correctly predicted as those at a high risk of SCD by using methods recommended by the 2019 enhanced ACC/AHA strategy, 20 (51.3%) by the 2011 ACCF/AHA guideline, but only 5 (12.8%) by the 2014 ESC guideline. The 2019 enhanced ACC/AHA strategy showed a higher C-statistic (0.647) for SCD prediction than did the 2011 ACCF/AHA guideline (0.598) and 2014 ESC guideline (0.605) and resulted in the correct reclassification of SCD risk when compared with the 2011 ACCF/AHA guideline (net reclassification index 0.113; P = .074) and 2014 ESC guideline (net reclassification index 0.245; P = .038).

CONCLUSION

The 2019 enhanced ACC/AHA strategy showed better predictive performance for SCD risk stratification in Chinese patients with HCM, with a notably high sensitivity.

Additive prognostic significance of ejection fraction for ESC risk model in hypertrophic cardiomyopathy patients

The European Society of Cardiology (ESC) clinical risk model is reported in predicting sudden death of hypertrophic cardiomyopathy (HCM). We examined the validity of this model and investigated the significance of ejection fraction (EF) in predicting the prognosis using ESC risk model in HCM patients. 305 HCM patients (198 males) were followed (median follow-up 4.8 years) for life-threatening arrhythmic events (sudden death, aborted sudden death, sustained VT/VF, appropriate ICD intervention for VT/VF) and were divided using ESC risk model into low- (Group L), intermediate- (Group I) and high- (Group H) risk groups. There was a significant difference in the events rate among the 3 groups (L, 0.9%/year; I, 3.9%/year; H, 6.8%/year; log-rank p < 0.001) in all study patients. Reduced EF (<50%) was identified in 27 (8.9%) cases. There was a significant difference in the events rate among the 3 groups in patients with reduced EF (L, 2.4%/year; I, 4.9%/year; H, 16.1%/year; log-rank p = 0.025). There was a significant difference in the events rate among 2 groups in patients stratified as Group H (preserved EF, 3.1%/year vs. reduced EF, 16.1%/year; log-rank p = 0.041). ESC risk model precisely predicts life-threatening events in patients with HCM. Adding EF to ESC risk model are useful for further risk stratification of life-threatening arrhythmic events.

The electrocardiogram in the diagnosis and management of patients with hypertrophic cardiomyopathy

In an era of rapid technological development and evolving diagnostic possibilities, the electrocardiogram (ECG) is living an authentic "renaissance" in myocardial diseases. To date, the ECG remains an irreplaceable first step when evaluating patients with hypertrophic cardiomyopathy (HCM) and an abnormal ECG may be the only manifestation of disease at an early stage. In some instances, specific electrical anomalies may differentiate HCM from phenocopies such as cardiac amyloidosis and glycogen storage diseases. The exponential growth in knowledge of the complexity of HCM has led to new challenges in terms of early identification of the disease, differential diagnosis, risk stratification, and development of targeted therapies. In this scenario, the apparently "old fashioned" ECG and the array of ECG-based techniques, ranging from Holter monitoring and loop recorders to exercise testing, are as contemporary as ever. In the present review, we discuss the current role of the ECG in the diagnosis and management of HCM, focusing on various clinical settings where its appropriate use and interpretation can make a difference.

Paradigm of Sudden Death Prevention in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a worldwide genetic heart disease and a common cause of sudden death in the young. Penetration of the implantable cardioverter-defibrillator (ICD) into this patient population over the past 20 years has made accurate selection of patients for primary prevention ICDs a priority. Consequently, a new paradigm has emerged in the management of this complex disease with ICD therapy responsible for a substantial decrease in overall HCM-related mortality (to 0.5%/y) and independent of patient age. Selection of candidates for ICDs has matured substantially with the formulation of an enhanced risk stratification algorithm. One or more contemporary risk markers judged major within a given patient’s clinical profile, in association with physician judgment and shared decision-making, is sufficient to consider a primary prevention ICD implant. An enhanced American College of Cardiology/American Heart Association risk factor model (including new contrast-magnetic resonance–based markers, such as left ventricular apical aneurysm) used prospectively to make ICD decisions proved to be 95% sensitive for identifying patients who would experience ≥1 appropriate device therapies terminating ventricular tachycardia/fibrillation. The number of HCM patients required to treat with ICDs to save 1 patient with abolition of lethal ventricular tachyarrhythmias was 6:1, similar to randomized defibrillator trials in other cardiomyopathies. In contrast to patients with ischemic heart disease, after ICD shock HCM patients rarely experience transformation to heart failure deterioration or sudden arrhythmic death. The mathematically derived risk score model proposed by the European Society of Cardiology was inferior for identifying high-risk patients susceptible to arrhythmic sudden death with a sensitivity of only 33%, leaving many patients exposed to the possibility of sudden death without ICDs. In conclusion, introduction of the ICD associated with a matured risk stratification algorithm has altered management strategy and clinical course of many HCM patients, making the likelihood of sudden death prevention a reality and fulfilling the aspiration of preservation of life and reduced mortality for this vulnerable patient population.

The subcutaneous implantable cardioverter-defibrillator: Current trends in clinical practice between guidelines and technology progress

The subcutaneous implantable cardioverter defibrillator (S-ICD) is a valuable alternative to the conventional trans-venous ICD (TV-ICD) for the prevention of sudden cardiac death (SCD). Prospective registries showed that the S-ICD is safe and effective in treating ventricular tachyarrhythmias in high-risk patients without pacing indications. While in earlier studies patients implanted with S-ICDs were young and mostly affected by channelopathies, contemporary S-ICD cohorts include patients with severely impaired left ventricular function and significant comorbidities. This review focuses on S-ICD evidence-based use and highlights current gaps between guidelines recommendations and real-world clinical practice.