Predictors of sudden cardiac death in hypertrophic cardiomyopathy

Sudden Death Risk Assessment in Hypertrophic Cardiomyopathy Across the Lifespan: Reconciling the American and European Approaches

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiac disease. Since the modern description of HCM more than seven decades ago, great focus has been placed on preventing its most catastrophic complication: sudden cardiac death (SCD). Implantable cardioverter-defibrillators (ICD) have been recognized to provide effective prophylactic therapy. Over the years, two leading societies, the European Society of Cardiology (ESC) and the American Heart Association/American College of Cardiology (AHA/ACC), have proposed risk stratification models to assess SCD in adults. European guidelines rely on a risk calculator, the HCM Risk-SCD, while American guidelines propose a stand-alone risk factor approach. Recently, risk prediction models were also developed in the pediatric population. This article reviews the latest recommendations on the risk stratification of SCD in HCM and summarises current indications for ICD use.

Safety and efficacy of mavacamten for treatment of hypertrophic cardiomyopathy: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Mavacamten, an allosteric myosin inhibitor, is considered to be a promising drug for the treatment of hypertrophic cardiomyopathy (HCM). This meta-analysis aimed to explore the safety and efficacy of mavacamten in HCM patients.

MAIN BODY

A total number of 539 patients were enrolled in four randomized clinical trials. The mean age of patients was 57.9 years and was followed for 29.3 weeks. Pooled analysis showed a significant improvement in clinical response (Log OR = 0.65; p = 0.01) and the number of patients with a reduction of ≥ 1 NYHA function class (Log OR = 0.64, p = 0.00). It was found that mavacamten did not significantly affect the Kansas City Cardiomyopathy Questionnaire (KCCQ) (SMD = 0.43, p = 0.08), peak oxygen uptake (PVO₂) (SMD = 0.24, p = 0.42), and ejection fraction (EF) (SMD = - 0.65, p = 0.13) as compared with placebo. However, KCCQ (SMD = 0.65, 95% CI 0.44-0.87) and PVO₂ (SMD = 0.49, 95% CI 0.24-0.74) improvements were statically significant in the hypertrophic obstructive cardiomyopathy subgroup (HOCM), and a significant decrease in EF (SMD = -- 1.14, 95% CI - 1.86 to - 0.42) was found in the HOCM subgroup. No significant difference was observed in the incidence rate of serious adverse events between mavacamten and placebo group (Log OR = - 0.23, p = 0.56).

CONCLUSIONS

Mavacamten proved to be effective and well-tolerated for the treatment of HCM. Mavacamten improved the signs and symptoms of HOCM and decreased EF in these patients without serious adverse events in the clinical trials.

Midterm Outcome After Septal Myectomy and Medical Therapy in Mildly Symptomatic Patients With Hypertrophic Obstructive Cardiomyopathy

Objective

The purpose of this study was mainly to determine the midterm outcome of septal myectomy (SM) and medical therapy (MT) in mildly symptomatic patients (NYHA class II) with hypertrophic obstructive cardiomyopathy (HOCM).

Methods

The study cohort consisted of 184 mildly symptomatic patients with HOCM evaluated in Beijing Anzhen Hospital, Capital Medical University between March 2001 and December 2017, including 82 patients in the SM group and 102 patients in the MT group. Overall survival and HCM-related survival were mainly observed.

Results

The average follow-up time was 5.0 years. Compared to patients accepting MT, patients treated with SM were associated with comparable overall survival (96.5% and 93.1% vs. 92.9% and 83.0% at 5 and 10 years, respectively; P = 0.197) and HCM-related survival (98.7% and 98.7% vs. 94.2% and 86.1% at 5 and 10 years, respectively; P = 0.063). However, compared to MT, SM was superior at improvement of NYHA class (1.3 ± 0.6 vs. 2.1 ± 0.5, P < 0.001) and mean reduction of resting left ventricular outflow (LVOT) gradient (78.5 ± 18.6% vs. 28.3 ± 18.4%, P < 0.001). Multivariate analysis suggested that resting LVOT gradient in the last clinical examination was an independent predictor of all-cause mortality (HR = 1.017, 95%CI: 1.000–1.034, P = 0.045) and HCM-related mortality (HR = 1.024, 95%CI: 1.005–1.043, P = 0.012) in the entire cohort.

Conclusion

Compared with MT, SM had comparable overall survival and HCM-related survival in mildly symptomatic HOCM patients, but SM had advantages on improving clinical symptoms and reducing resting LVOT gradient. Resting LVOT gradient in the last clinical examination was an independent predictor of all-cause mortality and HCM-related mortality.

Sudden cardiac death in cardiomyopathies: acting upon "acceptable" risk in the personalized medicine era

Patients with cardiomyopathies are confronted with the risk of sudden cardiac death (SCD) throughout their lifetime. Despite the fact that SCD is relatively rare, prognostic stratification is an integral part of physician-patient discussion, with the goal of risk modification and prevention. The current approach is based on a concept of "acceptable risk." However, there are intrinsic problems with an algorithm-based approach to risk management, magnified by the absence of robust evidence underlying clinical decision support tools, which can make high- versus low-risk classifications arbitrary. Strategies aimed at risk reduction range from selecting patients for an implantable cardioverter defibrillator (ICD) to disqualification from competitive sports. These clinical options, especially when implying the use of finite financial resources, are often delivered from the physician's perspective citing decision-making algorithms. When the burden of intervention-related risks or financial costs is deemed higher than an "acceptable risk" of SCD, the patient's perspective may not be appropriately considered. Designating a numeric threshold of "acceptable risk" has ethical implications. One could reasonably ask "acceptable to whom?" In an era when individual choice and autonomy are pillars of the physician-patient relationship, the subjective aspects of perceived risk should be acknowledged and be part of shared decision-making. This is particularly true when the lack of a strong scientific evidence base makes a dichotomous algorithm-driven approach suboptimal for unmitigated translation to clinical practice.

Risk Prediction Models and Scores in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) has historically been linked with sudden cardiac death (SCD). Currently, it is well established that only a subset of patients is at the highest risk stratum for such a catastrophic event. Detection of patients belonging to this high-risk category can allow for timely defibrillator implantation, changing the natural history of HCM. Inversely, device implantation in patients deemed at low risk leads to an unnecessary burden of device complications with no apparent protective benefit. Previous studies have identified a series of markers, now considered established risk factors, with genetic testing and newer imaging allowing for the detection of novel, highly promising indices of increased risk for SCD. Despite the identification of a number of risk factors, there is noticeable discrepancy in the utility of such factors for risk stratification between the current American and European guidelines. We sought to systematically review the data available on these two approaches, presenting their rationale and respective predictive capacity, also discussing the potential of novel markers to augment the precision of currently used risk stratification models for SCD in HCM.

Left intraventricular pressure gradient in hypertrophic cardiomyopathy patients receiving implantable cardioverter-defibrillators for primary prevention

Background

Conventional risk factors for sudden cardiac death (SCD) justify primary prevention through implantable cardioverter-defibrillator (ICD) implantation in hypertrophic cardiomyopathy (HCM) patients. However, the positive predictive values for these conventional SCD risk factors are low. Left ventricular outflow tract obstruction (LVOTO) and midventricular obstruction (MVO) are potential risk modifiers for SCD. The aims of this study were to evaluate whether an elevated intraventricular pressure gradient (IVPG), including LVOTO or MVO, is a potential risk modifier for SCD and ventricular arrhythmias requiring ICD interventions in addition to the conventional risk factors among HCM patients receiving ICDs for primary prevention.

Methods

We retrospectively studied 60 HCM patients who received ICDs for primary prevention. An elevated IVPG was defined as a peak instantaneous gradient ≥ 30 mmHg at rest, as detected by continuous-wave Doppler echocardiography. The main outcome was a composite of SCD and appropriate ICD interventions, which were defined as an antitachycardia pacing or shock therapy for ventricular tachycardia or fibrillation. The Cox proportional hazards model was used to assess the relationships between risk factors and the occurrence of SCD and appropriate ICD interventions.

Results

Thirty patients met the criteria of elevated IVPG (50%). During the median follow-up period of 66 months, 2 patients experienced SCD, and 10 patients received appropriate ICD interventions. Kaplan–Meier curves showed that the incidence of the main outcome was higher in patients with an IVPG ≥ 30 mmHg than in those without an IVPG ≥ 30 mmHg (log-rank P = 0.03). There were no differences in the main outcome between patients with LVOTO and patients with MVO. The combination of nonsustained ventricular tachycardia (NSVT) and IVPG ≥ 30 mmHg was found to significantly increase the risk of the main outcome (HR 6.31, 95% CI 1.36–29.25, P = 0.02). Five patients experienced ICD implant-related complications.

Conclusions

Our findings showed that a baseline IVPG ≥ 30 mmHg was associated with an increased risk of experiencing SCD or appropriate ICD interventions among HCM patients who received ICDs for primary prevention. Combined with NSVT, which is a conventional risk factor, a baseline IVPG ≥ 30 mmHg may be a potential modifier of SCD risk in HCM patients.

Risk stratification using late gadolinium enhancement on cardiac magnetic resonance imaging in patients with hypertrophic cardiomyopathy: A systematic review and meta-analysis

Background The role of late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (c-MRI) for predicting outcomes of patients with hypertrophic cardiomyopathy (HCM) has been debated. Methods We searched PubMed and Embase and various published bibliographies for prospective studies published in English between January 1990 and February 2019. Two investigators screened 2646 abstracts and full-text articles for inclusion and relevant outcomes. We then performed a systematic review and meta-analysis to calculate pooled odds ratios for LGE on c-MRI and a pooled sensitivity and specificity analysis. Results Our systematic review included 8 prospective studies and 3808 patients. LGE positivity was associated with higher odds of the endpoint of sudden cardiac death (SCD;OR 1.69, 95%CI 1.03-2.78), aborted SCD or appropriate implantable cardioverter- defibrillator (ICD) discharge (OR 3.27 [1.75-6.10]), SCD or aborted SCD or appropriate ICD discharge (OR 2.32 [1.56-3.43]), and all-cause mortality (OR 2.10 [CI 1.00-4.41]). The pooled sensitivity and specificity of positive LGE on c-MRI for SCD were 65% and 42%, respectively; for aborted SCD or appropriate ICD discharge, 79% and 39%; for SCD or aborted SCD or appropriate ICD discharge, 74% and 39%; and for all-cause mortality, 78% and 39%. Conclusion In patients with HCM, LGE on c-MRI is a strong predictor of arrhythmic outcomes including SCD, aborted SCD, and appropriate ICD therapy. These data support the routine use of LGE on c-MRI as a marker of SCD risk in this population.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. The disease is characterized by marked variability in morphological expression and natural history, ranging from asymptomatic to heart failure or sudden cardiac death. Left ventricular hypertrophy and abnormal ventricular configuration result in dynamic left ventricular outflow obstruction in most patients. The goal of pharmacological therapy in HCM is to alleviate the symptoms, and it includes pharmacotherapies and septal reduction therapies. In this review, we summarize the relevant clinical issues and treatment options of HCM.

Myocardial tissue characterization by gadolinium-enhanced cardiac magnetic resonance imaging for risk stratification of adverse events in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic cardiomyopathy with a wide spectrum of clinical manifestations. Patients can be asymptomatic or suffer major adverse events including sudden cardiac death, ventricular arrhythmias, and heart failure. Identification of individuals with HCM who are at risk for these complications remains challenging. While echocardiography remains the mainstay of diagnostic evaluation, cardiac magnetic resonance imaging (CMR) is an important adjunctive diagnostic modality with emerging applications for risk-stratification of adverse events in the HCM population. Although not included in current guidelines for HCM management, there is increasing evidence to support the use of CMR for routine prognostic assessment of HCM patients. In this review we discuss the use of CMR techniques, including late gadolinium enhancement, T1 mapping, and quantification of extracellular volume fraction, for the risk stratification of three major adverse events in HCM: sudden cardiac death, ventricular arrhythmias, and congestive heart failure.

Risk stratification in hypertrophic cardiomyopathy

Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM). The greatest challenge in the management of HCM is identifying those at increased risk, since an implantable cardioverter-defibrillator (ICD) is a potentially life-saving therapy. We sought to summarize the available data on SCD in HCM and provide a clinical perspective on the current differing and somewhat conflicting data on risk stratification, with balanced guidance regarding rational clinical decision-making. Additionally, we sought to determine the status of the current implementation of guidelines compiled by HCM experts worldwide. The HCM Risk-SCD model helps improve the risk stratification of HCM patients for primary prevention of SCD by calculating an individual risk estimate that contributes to the clinical decision-making process. Improved risk stratification is important for decision-making before ICD implantation for the primary prevention of SCD.

Prognostic significance of left ventricular end diastolic pressure using E/E' in patients with hypertrophic cardiomyopathy

BACKGROUND

Left ventricular (LV) diastolic dysfunction is a prominent feature of hypertrophic cardiomyopathy (HCM). Prediction of LV filling pressure using the ratio between early diastolic transmitral flow and mitral annular velocity (E/e') had proved a good accuracy.

AIM OF THIS STUDY

We investigated the value of E/e' to predict cardiovascular (CV) mortality in patients with HCM.

METHODS

A total of 243 patients with HCM had E/e' measured in combination with clinical evaluation, conventional echocardiographic measurements, cardiopulmonary exercise evaluation, and Holter monitoring.

RESULTS

During a mean follow-up of (3.2 ± 1.2 years), 17 (7%) patients died. Non survivors had significantly higher SBP, DBP, left ventricular outflow tract obstruction (LVOTO) gradient, mitral E, and E/e', but lower e' of mitral annulus and more prevalent restrictive filling pattern. E/e' was directly correlated with age (r = .24, P < .005), left atrial volume index (r = .44, P < .0001), LVMI (r=0.23,P<.005), LVOT gradient (r = .43, P < .0001), NYHA class (r = .19, P < .006), pulmonary artery pressure (r = .24, P < .005), positive family history of HCM (r = .22, P < .005), and inversely related to peak systolic velocity (S) (r = .44, P < .0001). By multivariate analysis, only LVOTO ([RR] 4.11, 95% CI 1.002 to 1.148, P < .04) and E/e' were independent predictors for overall mortality in HCM (relative risk [RR] 5.27, 95% CI 1.002 to 1.024, P < .02). The risk of dying increased with increasing E/e' ratio, being approximately 4 times higher for patients in the highest quartile (HR 3.8 (CI 1.38-5.12, log-rank < 0.002)).

CONCLUSIONS

In hypertrophic cardiomyopathy, the E/e' ratio remains a powerful predictor of all-cause mortality, particularly if it is associated with LVOT obstruction.

Hypertrophic cardiomyopathy: genetics and clinical perspectives

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease and defined by unexplained isolated progressive myocardial hypertrophy, systolic and diastolic ventricular dysfunction, arrhythmias, sudden cardiac death and histopathologic changes, such as myocyte disarray and myocardial fibrosis. Mutations in genes encoding for proteins of the contractile apparatus of the cardiomyocyte, such as β-myosin heavy chain and myosin binding protein C, have been identified as cause of the disease. Disease is caused by altered biophysical properties of the cardiomyocyte, disturbed calcium handling, and abnormal cellular metabolism. Mutations in sarcomere genes can also activate other signaling pathways via transcriptional activation and can influence non-cardiac cells, such as fibroblasts. Additional environmental, genetic and epigenetic factors result in heterogeneous disease expression. The clinical course of the disease varies greatly with some patients presenting during childhood while others remain asymptomatic until late in life. Patients can present with either heart failure symptoms or the first symptom can be sudden death due to malignant ventricular arrhythmias. The morphological and pathological heterogeneity results in prognosis uncertainty and makes patient management challenging. Current standard therapeutic measures include the prevention of sudden death by prohibition of competitive sport participation and the implantation of cardioverter-defibrillators if indicated, as well as symptomatic heart failure therapies or cardiac transplantation. There exists no causal therapy for this monogenic autosomal-dominant inherited disorder, so that the focus of current management is on early identification of asymptomatic patients at risk through molecular diagnostic and clinical cascade screening of family members, optimal sudden death risk stratification, and timely initiation of preventative therapies to avoid disease progression to the irreversible adverse myocardial remodeling stage. Genetic diagnosis allowing identification of asymptomatic affected patients prior to clinical disease onset, new imaging technologies, and the establishment of international guidelines have optimized treatment and sudden death risk stratification lowering mortality dramatically within the last decade. However, a thorough understanding of underlying disease pathogenesis, regular clinical follow-up, family counseling, and preventative treatment is required to minimize morbidity and mortality of affected patients. This review summarizes current knowledge about molecular genetics and pathogenesis of HCM secondary to mutations in the sarcomere and provides an overview about current evidence and guidelines in clinical patient management. The overview will focus on clinical staging based on disease mechanism allowing timely initiation of preventative measures. An outlook about so far experimental treatments and potential for future therapies will be provided.

Sudden Cardiac Death Risk Stratification and the Role of the Implantable Cardiac Defibrillator

Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of sudden cardiac death (SCD), although perhaps not as significantly as previously believed. Given the heterogeneous nature of this disease entity, risk stratification of individuals with HCM remains challenging. The recent HCM risk-SCD prediction model seems to perform well in assessing individual SCD risk. Even though implantable cardiac defibrillators (ICDs) are effective in preventing SCD in patients at increased risk, the importance of shared decision making in deciding whether or not to undergo ICD implantation cannot be understated.

Modes of death and clinical outcomes in adult patients with hypertrophic cardiomyopathy in Thailand

Background

There are limited data about modes of death and major adverse cardiovascular events (MACEs) in patients with hypertrophic cardiomyopathy (HCM) in South East Asian population. The aim of the study was to examine modes of death and clinical outcomes in Thai patients with HCM.

Methods

Between January 1, 2009 and December 31, 2013, 166 consecutive patients with HCM diagnosed in our institution were evaluated. Five patients were excluded because of non-Thai ethnic groups (n = 3) and diagnosis of myocardial infarction at initial presentation documented by coronary angiography (n = 2). The final study population consisted of 161 patients with HCM. HCM-related deaths included: (1) sudden cardiac death (SCD) – death due to sudden cardiac arrest or unexpected sudden death; (2) heart failure – death due to refractory heart failure; or (3) stroke - death due to embolic stroke associated with atrial fibrillation. MACEs included: (1) SCD, sudden unexpected aborted cardiac arrest, fatal, or nonfatal ventricular arrhythmia (ventricular fibrillation or sustained ventricular tachycardia); (2) heart failure (fatal or non-fatal), or heart transplantation; or (3) stroke - fatal or non-fatal embolic stroke associated with atrial fibrillation.

Results

One hundred and sixty-one Thai patients with HCM (age 66 ± 16 years, 58% female) were enrolled. Forty-two patients (26%) died over a median follow-up period of 6.8 years including 25 patients (16%) with HCM-related deaths (2%/year). The HCM-related deaths included: heart failure (52% of HCM-related deaths; n = 13), SCD (44% of HCM-related deaths; n = 11), and stroke (4% of HCM-related deaths, n = 1). The SCDs occurred in 6.8% of patients (1%/year). Eighty-four major MACEs occurred in 65 patients (41, 5%/year). The MACEs included: 40 heart failures in which 2 patients underwent heart transplants; 22 SCDs and nonfatal ventricular arrhythmias; and 22 fatal or nonfatal strokes.

Conclusions

The most common mode of death in adult patients with HCM in Thailand was heart failure followed by SCD. About one-third of the patients experiencing heart failure died during the 6.8 years of follow-up. SCDs occurred in 7% of patients (1%/year), predominantly in the fourth decade or later.

Lifestyle Modification and Medical Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is a heterogenous condition associated with a myriad of symptoms. Just as in other disease states, the aim of medical therapy is the alleviation of suffering, improvement of longevity, and the prevention of complications. This article focuses on the associated comorbidities seen in patients with hypertrophic cardiomyopathy, potential lifestyle interventions, and conventional medical treatments for symptomatic hypertrophic cardiomyopathy.

Prevention of sudden death in hypertrophic cardiomyopathy: bridging the gaps in knowledge

Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM). Although the annual rate of SCD in the general HCM population is <1% per year according to contemporary series, there is still a small subset of patients who are at increased risk of SCD. The greatest challenge in the management of HCM is identifying those at increased risk as an implantable cardioverter defibrillator is a potentially life-saving therapy. In this review, we sought to summarize the available data on SCD in HCM and provide a clinical perspective on the current differing and somewhat conflicting European and American recommendations on risk stratification, with balanced guidance with regards to rational clinical decision making. Additionally, we sought to learn more on the actual implementation of the guidelines by HCM experts worldwide.

Comparison of the Prognostic Usefulness of the European Society of Cardiology and American Heart Association/American College of Cardiology Foundation Risk Stratification Systems for Patients With Hypertrophic Cardiomyopathy

Implantable cardiodefibrillators (ICDs) have proven benefit in preventing sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HC), making risk stratification essential. Data on the predictive accuracy on the European Society of Cardiology (ESC) risk scoring system have been conflicting. We independently evaluated the ESC risk scoring system in our cohort of patients with HC from a large tertiary center and compared this with previous guidance by the American College of Cardiology Foundation and Heart Association (ACCF/AHA). Risk factor profiles, 5-year SCD risk estimates, and ICD recommendations, as defined by the ACCF/AHA and ESC guidelines, were retrospectively ascertained for 288 HC patients with and without SCD or equivalent events at our center. In the SCD group (n = 14), a significantly higher proportion of patients would not have met the criteria for an ICD implant using the ESC scoring algorithm compared with ACCF/AHA guidance (43% vs 7%, p = 0.029). In those without SCD events (n = 274), a larger proportion of individuals not requiring an ICD was identified using the ESC risk score model compared with the ACCF/AHA model (82% vs 57%; p < 0.0001). Based on risk stratification criteria alone, 5 more individuals with a previously aborted SCD event would not have received an ICD with the ESC risk model compared with the ACCF/AHA risk model. In conclusion, we found that the current ESC scoring system potentially leaves more high-risk patients unprotected from sudden death in our cohort of patients.

Risk assessment of the occurrence of sudden death related to hypertrophic cardiomyopathy in Dakar

Objectifs

La cardiomyopathie hypertrophique (CMH) est l’une des principales causes de mort subite (MS) du sujet jeune, notamment chez le sportif de moins de 35 ans. Le niveau de risque est variable et nécessite d’être évalué afin d’adopter une stratégie préventive adaptée. Nous avons entrepris ce travail dans le but d’évaluer le risque de survenue de mort subite dans une population de CMH à Dakar.

Méthode

Il s’agissait d’une étude transversale et descriptive menée à la clinique cardiologique de l’hôpital Aristide Le Dantec de Dakar du 1er Janvier 2014 au 30 Juin 2015. Nous avions évalué sur le plan clinique et paraclinique les facteurs de risque de mort subite et utilisé le score en ligne de l’European Society of Cardiology (ESC) pour le calcul de ce risque. La population étudiée était constituée de patients porteurs de CMH diagnostiquée, suivis dans ledit service.

Résultats

Nous avions retrouvé un âge moyen des patients de 53.25 ans et il y avait une prédominance masculine (sexratio de 1.66). La syncope inexpliquée était retrouvée chez 2 patients et 2 autres avaient des antécédents de survenue de mort subite dans leurs familles à des âges de 50 ans et 55 ans. L’hypertrophie septale maximale était en moyenne de 20.9 mm. Quatorze patients présentaient une dilatation auriculaire gauche. Sept patients présentaient une obstruction intra-ventriculaire gauche. Selon le score ESC, 1 patient avait un haut risque de survenue de mort subite dans les 5 ans, 3 un risque intermédiaire et 13 un risque faible. Le sport de compétition était proscrit, 13 patients étaient sous traitement médical, 1 avait eu un défibrillateur automatique implantable (DAI) et 2 n’étaient sous aucun traitement.

Conclusion

Notre travail a mis en exergue une prédominance de risque faible et intermédiaire de mort subite à 5 ans. Le haut risque existait dans un cas.

Sudden Cardiac Death in Genetic Cardiomyopathies

Sudden cardiac death (SCD) caused by ventricular arrhythmias is common in patients with genetic cardiomyopathies (CMs) including dilated CM, hypertrophic CM, and arrhythmogenic right ventricular CM (ARVC). Phenotypic features can identify individuals at high enough risk to warrant placement of an implantable cardioverter-defibrillator, although risk stratification schemes remain imperfect. Genetic testing is valuable for family cascade screening but with few exceptions (eg, LMNA mutations) do not identify higher risk for SCD. Although randomized trials are lacking, observational data suggest that ICDs can be beneficial. Vigorous exercise can exacerbate ARVC disease progression and increase likelihood of ventricular arrhythmias.

Hypertrophic Cardiomyopathy-Past, Present and Future

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy with a prevalence of 1 in 500 in the general population. Since the first pathological case series at post mortem in 1957, we have come a long way in its understanding, diagnosis and management. Here, we will describe the history of our understanding of HCM including the initial disease findings, diagnostic methods and treatment options. We will review the current guidelines for the diagnosis and management of HCM, current gaps in the evidence base and discuss the new and promising developments in this field.

Inverted U-Shaped Relation Between the Risk of Sudden Cardiac Death and Maximal Left Ventricular Wall Thickness in Hypertrophic Cardiomyopathy

Background—

Hypertrophic cardiomyopathy is associated with sudden cardiac death (SCD). Some studies have shown an association between risk of sudden death and left ventricular maximal wall thickness (MWT), but there are few data in patients with extreme hypertrophy. The aim of this study was to determine the relation between MWT and the risk of SCD.

Methods and Results—

This is a multicenter, retrospective, longitudinal cohort study of 3673 adult (≥16 years) patients, previously used to develop and validate a risk prediction model for SCD (HCM Risk-SCD [hypertrophic cardiomyopathy risk-SCD]). There was an inverted U-shaped relation between MWT and the estimated 5-year risk of SCD. In patients with MWT≥35 mm (n=47; mean age, 33 years; 81% men), there was a single SCD end point (annual rate, 0.2%; 95% confidence interval, 0.03–1.60) and 3 additional cardiovascular events during a median follow-up of 9.5 years. Compared with patients with MWT≤14 mm, those with MWT≥35 mm did not have a higher risk for SCD (hazard ratio, 0.22; 95% confidence interval, 0.03–1.65), cardiovascular death (hazard ratio, 0.66; 95% confidence interval, 0.26–1.67), or all-cause mortality (hazard ratio, 0.73; 95% confidence interval, 0.32–1.69).

Conclusions—

The risk of SCD has a complex, nonlinear relationship to MWT. The pathophysiological mechanisms behind this observation require further study but implantable cardioverter defibrillator implantation should not be guided solely on the severity of left ventricular hypertrophy.

ICD Therapy for Primary Prevention in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common and heterogeneous disorder that increases an individual's risk of sudden cardiac death (SCD). This review article discusses the relevant factors that are involved in the challenge of preventing SCD in patients with HCM. The epidemiology of SCD in patients is reviewed as well as the structural and genetic basis behind ventricular arrhythmias in HCM. The primary prevention of SCD with implantable cardioverter-defibrillator (ICD) therapy is the cornerstone of modern treatment for individuals at high risk of SCD. The focus here is on the current and emerging predictors of SCD as well as risk stratification recommendations from both North American and European guidelines. Issues related to ICD implantation, such as programming, complications and inappropriate therapies, are discussed. The emerging role of the fully subcutaneous ICD and the data regarding its implantation are reviewed.

The role of imaging in the diagnosis and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, affecting approximately 1:500 people. As the yield of genetic testing is only about 35-60%, the diagnosis of HCM is still clinical and based on the demonstration of unexplained and usually asymmetric left ventricular (LV) hypertrophy by imaging modalities. In the past, echocardiography was the sole imaging modality used for the diagnosis and management of HCM. However, in recent years other imaging modalities such as cardiac magnetic resonance have played a major role in the diagnosis, management and risk stratification of HCM, particularly when the location of left ventricular hypertrophy is atypical (apex, lateral wall) and when the echocardiographic imaging is sub-optimal. However, the most unique contribution of cardiac magnetic resonance is the quantification of myocardial fibrosis. Exercise stress echocardiography is the preferred provocative test for the assessment of LV outflow tract obstruction, which is detected only on provocation in one-third of the patients.

Quantification and significance of diffuse myocardial fibrosis and diastolic dysfunction in childhood hypertrophic cardiomyopathy

The purpose of this study was to evaluate the presence of diffuse myocardial fibrosis in children and adolescents with hypertrophic cardiomyopathy (HCM) and to assess associations with echocardiographic and clinical parameters of disease. While a common end point in adults with HCM, it is unclear whether diffuse myocardial fibrosis occurs early in the disease. Cardiac magnetic resonance (CMR) estimation of myocardial post-contrast longitudinal relaxation time (T1) is an increasingly used method to estimate diffuse fibrosis. T1 measurements were taken using standard multi-breath-hold spoiled gradient echo phase-sensitive inversion-recovery CMR before and 15 min after the injection of gadolinium. The tissue-blood partition coefficient was calculated as a function of the ratio of T1 change of myocardium compared with blood. An echocardiogram and blood brain natriuretic peptide (BNP) levels were obtained on the day of the CMR. Twelve controls (mean age 12.8 years; 7 male) and 28 patients with HCM (mean age 12.8 years; 21 male) participated. The partition coefficient for both septal (0.27 ± 0.17 vs. 0.13 ± 0.09; p = 0.03) and lateral walls (0.22 ± 0.09 vs. 0.07 ± 0.10; p < 0.001) was increased in patients compared with controls. Eight patients had overt areas of late gadolinium enhancement (LGE). These patients did not show increased partition coefficient compared with those without LGE (0.27 ± 0.15 vs. 0.27 ± 0.19 and 0.22 ± 0.09 vs. 0.22 ± 0.09; p = 0.95 and 0.98, respectively). However, patients who were symptomatic (dyspnea, arrhythmia and/or chest pain) had higher lateral wall partition coefficient than asymptomatic HCM patients (0.27 ± 0.08 vs. 0.17 ± 0.08; p = 0.006). Similarly, patients with raised BNP (>100 pg/ml) had raised lateral wall coefficients (0.27 ± 0.07 vs. 0.20 ± 0.07; p = 0.03), as did those with traditional risk factors for sudden death (0.27 ± 0.06 vs. 0.18 ± 0.08; p = 0.007). Diffuse fibrosis, measured by the partition coefficient technique, is demonstrable in children and adolescents with HCM. Markers of fibrosis show an association with symptoms and raised serum BNP. Further study of the prognostic implication of this technique in young patients with HCM is warranted.

Validation of the 2014 European Society of Cardiology guidelines risk prediction model for the primary prevention of sudden cardiac death in hypertrophic cardiomyopathy

BACKGROUND

The recently released 2014 European Society of Cardiology guidelines of hypertrophic cardiomyopathy (HCM) use a new clinical risk prediction model for sudden cardiac death (SCD), based on the HCM Risk-SCD study. Our study is the first external and independent validation of this new risk prediction model.

METHODS AND RESULTS

The study population consisted of a consecutive cohort of 706 patients with HCM without prior SCD event, from 2 tertiary referral centers. The primary end point was a composite of SCD and appropriate implantable cardioverter-defibrillator therapy, identical to the HCM Risk-SCD end point. The 5-year SCD risk was calculated using the HCM Risk-SCD formula. Receiver operating characteristic curves and C-statistics were calculated for the 2014 European Society of Cardiology guidelines, and risk stratification methods of the 2003 American College of Cardiology/European Society of Cardiology guidelines and 2011 American College of Cardiology Foundation/American Heart Association guidelines. During follow-up of 7.7±5.3 years, SCD occurred in 42 (5.9%) of 706 patients (ages 49±16 years; 34% women). The C-statistic of the new model was 0.69 (95% CI, 0.57-0.82; P=0.008), which performed significantly better than the conventional risk factor models based on the 2003 guidelines (C-statistic of 0.55: 95% CI, 0.47-0.63; P=0.3), and 2011 guidelines (C-statistic of 0.60: 95% CI, 0.50-0.70; P=0.07).

CONCLUSIONS

The HCM Risk-SCD model improves the risk stratification of patients with HCM for primary prevention of SCD, and calculating an individual risk estimate contributes to the clinical decision-making process. Improved risk stratification is important for the decision making before implantable cardioverter-defibrillator implantation for the primary prevention of SCD.

Diagnosis and management of hypertrophic cardiomyopathy

The clinical spectrum of hypertrophic cardiomyopathy (HCM) is complex and includes a variety of phenotypes, which leads to different types of manifestations. Although most of the patients are asymptomatic, a significant proportion of them will develop symptoms or risk of arrhythmias and sudden cardiac death (SCD). Therefore, the objectives of HCM diagnosis and management are to relieve the patients' symptoms (chest pain, heart failure, syncope, palpitations, etc.), prevent disease progression and major cardiovascular complications and SCD. The heterogeneity of HCM patterns, their symptoms and assessment is a challenge for the cardiologist.

Risk Stratification in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a hereditary primary myocardial disease that is most commonly due to mutations within genes encoding sarcomeric contractile proteins and is characterised by left ventricular hypertrophy in the absence of a cardiac or systemic cause. Although the overall prognosis is relatively good with an annual mortality rate <1 %, the propensity to potentially fatal ventricular arrhythmias is the most feared complication. The identification of patients at risk of arrhythmogenic sudden cardiac death (SCD) is an essential component in disease management. Aborted SCD and malignant ventricular arrhythmias are the most powerful risk factors for SCD and ICD implantation is recommended in such circumstances. The selection of patients who may benefit from ICD therapy for primary prevention purposes is more challenging. The heterogeneous nature of the disease and the variation in trigger factors provides an adequate explanation for the low predictive accuracy of most conventional risk factors in isolation. A new risk model for risk stratification proposed by the European Society of Cardiology HCM outcome group shows promise but requires validation in different cohorts. The ICD is the only effective therapy in preventing SCD for the disease with a relatively low adverse event rate, but most deaths occur in relatively young patients. However, it is also difficult to ignore the complications with the ICD, therefore, the strive to perfect risk stratification in HCM should continue to ensure that only the most high-risk patients receive an ICD.

A novel clinical risk prediction model for sudden cardiac death in hypertrophic cardiomyopathy (HCM risk-SCD)

AIMS

Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death (SCD) in young adults. Current risk algorithms provide only a crude estimate of risk and fail to account for the different effect size of individual risk factors. The aim of this study was to develop and validate a new SCD risk prediction model that provides individualized risk estimates.

METHODS AND RESULTS

The prognostic model was derived from a retrospective, multi-centre longitudinal cohort study. The model was developed from the entire data set using the Cox proportional hazards model and internally validated using bootstrapping. The cohort consisted of 3675 consecutive patients from six centres. During a follow-up period of 24 313 patient-years (median 5.7 years), 198 patients (5%) died suddenly or had an appropriate implantable cardioverter defibrillator (ICD) shock. Of eight pre-specified predictors, age, maximal left ventricular wall thickness, left atrial diameter, left ventricular outflow tract gradient, family history of SCD, non-sustained ventricular tachycardia, and unexplained syncope were associated with SCD/appropriate ICD shock at the 15% significance level. These predictors were included in the final model to estimate individual probabilities of SCD at 5 years. The calibration slope was 0.91 (95% CI: 0.74, 1.08), C-index was 0.70 (95% CI: 0.68, 0.72), and D-statistic was 1.07 (95% CI: 0.81, 1.32). For every 16 ICDs implanted in patients with ≥4% 5-year SCD risk, potentially 1 patient will be saved from SCD at 5 years. A second model with the data set split into independent development and validation cohorts had very similar estimates of coefficients and performance when externally validated.

CONCLUSION

This is the first validated SCD risk prediction model for patients with HCM and provides accurate individualized estimates for the probability of SCD using readily collected clinical parameters.

The case of 17-year-old male with LEOPARD syndrome

LEOPARD syndrome is a phenotypic expression of mutations in several genes: PTPN11, RAF1, and BRAF. All these genes are responsible for Ras/MARK signaling pathway, which are important for cell cycle regulation, differentiation, growth, and aging. Mutations result in anomalies of skin, skeletal, and cardiovascular systems. The LEOPARD syndrome means lentigines, electrocardiographic conducting abnormalities, ocular hypertelorism, pulmonary stenosis, abnormal genitalia, retarded growth, and deafness. Mutations affect tyrosine proteases, which are included in the signal pathway between the cell membrane and the nucleus. This rare autosomal dominant disorder is characterized by high variability of clinical manifestations. Usually only lentigines are common. Clinical diagnosis is based on lentigines and 2 other symptoms; in cases without lentigines - 3 symptoms and at least one affected first-line relative. Herein, we report the case of 17-year-old male who had idiopathic hypertrophic cardiomyopathy with left ventricular obstruction, and supraventricular and ventricular extasystoles, class IVa, left bundle branch block, as a life-threatening manifestation of LEOPARD syndrome. For the treatment of cardiac manifestations of this syndrome, the patient underwent two interventions: (1) mitral valve replacement by mechanical valve Optiform number 27 with surgical resection of left ventricular outflow tract and subaortic membrane excision; (2) implantable cardioverter-defibrillator therapy. <Learning objective: Explain the abbreviation L.E.O.P.A.R.D. (Lentigines, Electrocardiographic conducting abnormalities, Ocular hypertelorism, Pulmonary stenosis, Abnormal genitalia, Retarded growth, and Deafness). Suspect the signs of L.E.O.P.A.R.D.-syndrome. Realize the etiology. Evaluate probability of this congenital disease on the ground of the clinical manifestations and laboratory data. Measure the significance for health of changes of organs and systems. Choose the main and dangerous manifestation of L.E.O.P.A.R.D.-syndrome. Select the best way for treatment such patients.>.