Sudden cardiac death in nonischemic cardiomyopathy

Sudden cardiac death (SCD) is a major cause of mortality in patients with nonischemic cardiomyopathy (NICM). Identifying patients who are at highest risk for SCD is an ongoing challenge. At present, guidelines recommend the use of an implantable cardioverter-defibrillator (ICD) in patients with NICM with a reduced left ventricular ejection fraction (LVEF) and heart failure (HF) symptoms. Some recent data, however, suggest that ICDs may not increase longevity in this population. Conversely, community-based studies have demonstrated that many at-risk individuals who may benefit from ICD therapy remain unprotected. Current recommendations for ICD implantation are continually debated, justifying comprehensive individualized risk assessment. Various promising techniques for further risk stratification are under evaluation, including cardiac magnetic resonance imaging, electrocardiographic assessment of electrical instability, and genetic testing. However, none of these strategies has been fully adapted into guidelines. Hence, clinical risk stratification practice today depends on LVEF and HF symptoms, which have poor sensitivity and specificity for predicting SCD risk.     

Sudden cardiac death in patients with nonischemic cardiomyopathy

Sudden cardiac death (SCD) is an important cause of mortality worldwide. Although SCD is most often associated with coronary heart disease, the risk of SCD in patients without ischemic heart disease is well-established. Nonischemic cardiomyopathies, including idiopathic dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy represent three unique disease entities that have been shown to be highly associated with SCD and ventricular arrhythmias. A variety of risk stratification tools have been investigated, although the optimal strategy remains unknown. Identification of the arrhythmogenic substrate and treatment of ventricular arrhythmias in these subgroups can be challenging. Herein, we aim to discuss the current understanding of the anatomic and electrophysiologic substrate underlying ventricular arrhythmias and highlight features that may be associated with a higher risk of SCD in these 3 conditions.     

Hypertrophic cardiomyopathy: Can the noninvasive diagnostic testing identify high risk patients?

Hypertrophic cardiomyopathy(HCM) is the most common cause of sudden cardiac death(SCD) in the young, particularly among athletes. Identifying high risk individuals is very important for SCD prevention. The purpose of this review is to stress that noninvasive diagnostic testing is important for risk assessment. Extreme left ventricular hypertrophy and documented ventricular tachycardia and fibrillation increase the risk of SCD. Fragmented QRS and T wave inversion in multiple leads are more common in high risk patients. Cardiac magnetic resonance imaging provides complete visualization of the left ventricular chamber, allowing precise localization of the distribution of hypertrophy and measurement of wall thickness and cardiac mass. Moreover, with late gadolinium enhancement, patchy myocardial fibrosis within the area of hypertrophy can be detected, which is also helpful in risk stratification. Genetic testing is encouraged in all cases, especially in those with a family history of HCM and SCD.     

Arrhythmic risk stratification in ischemic,non-ischemic and hypertrophic cardiomyopathy: A two-step multifactorial,electrophysiology study inclusive approach

Annual arrhythmic sudden cardiac death ranges from 0.6% to 4% in ischemic cardiomyopathy (ICM), 1% to 2% in non-ischemic cardiomyopathy (NICM), and 1% in hypertrophic cardiomyopathy (HCM). Towards a more effective arrhythmic risk stratification (ARS) we hereby present a two-step ARS with the usage of seven non-invasive risk factors: Late potentials presence (≥ 2/3 positive criteria), premature ventricular contractions (≥ 30/h), non-sustained ventricular tachycardia (≥ 1episode/24 h), abnormal heart rate turbulence (onset ≥ 0% and slope ≤ 2.5 ms) and reduced deceleration capacity (≤ 4.5 ms), abnormal T wave alternans (≥ 65μV), decreased heart rate variability (SDNN < 70ms), and prolonged QT_c interval (> 440 ms in males and > 450 ms in females) which reflect the arrhythmogenic mechanisms for the selection of the intermediate arrhythmic risk patients in the first step. In the second step, these intermediate-risk patients undergo a programmed ventricular stimulation (PVS) for the detection of inducible, truly high-risk ICM and NICM patients, who will benefit from an implantable cardioverter defibrillator. For HCM patients, we also suggest the incorporation of the PVS either for the low HCM Risk-score patients or for the patients with one traditional risk factor in order to improve the inadequate sensitivity of the former and the low specificity of the latter.     

Implantable Cardioverter Defibrillator Therapy in Patients with Ischemic or Non-Ischemic Cardiomyopathy and Nonsustained Ventricular Tachycardia

BACKGROUND: Mortality benefit from implantable cardioverter defibrillator (ICD) therapy in ischemic cardiomyopathy (ICM) with non-sustained ventricular tachycardia (NS-VT) and inducible VT is well defined. Although NS-VT may suggest an increased risk of sudden cardiac death (SCD) in non-ischemic cardiomyopathy (NICM), the role of ICD therapy is unclear. This retrospective study compares follow-up data in these two groups after ICD implantation. METHODS: 153 consecutive patients with ICD implantation for NS-VT were analyzed. ICM patients received an ICD if they had inducible VT at electrophysiology study (EPS). NICM patients did not routinely undergo EPS before ICD implantation. RESULTS: There were 48 patients (33 males) in NICM group and 105 patients (89 males) in the ICM group. Baseline characteristics including mean ejection fraction (EF), distribution in various New York Heart Association (NYHA) classes, and the mean duration of follow up in the two groups were similar. 50% of the patients in the NICM group and 36% in the ICM group received appropriate therapies (p = 0.106). The mean number of appropriate therapies in the two groups were similar (23.3 +/- 56.7 and 22.5 +/- 59.5 respectively, p = NS). The percentage of patients with inappropriate therapies in the two groups were 27% and 23% respectively (p = NS). Patients in the NICM group received appropriate ICD discharges at a greater rate (p = 0.02). CONCLUSION: Patients undergoing ICD implantation for NICM and NS-VT receive appropriate ICD therapy at a greater rate than those implanted for ICM, NS-VT, and a positive EPS. Although these data do not prove survival benefit in NICM, they suggest a beneficial effect.     

The arrhythmogenic right ventricular cardiomyopathy in comparison to the athletic heart

Intense exercise‐induced right ventricular remodeling is a potential adaptation of cardiac function and structure. The features of the remodeling may overlap with those of a very early form of arrhythmogenic right ventricular cardiomyopathy (ARVC): at this early stage, it could be difficult to discriminate ARVC, from exercise‐induced cardiac adaptation that may develop in normal individuals. The purpose of this paper is to discuss which exercise‐induced remodeling may be a pathological or a physiological finding. A complete evaluation may be required to identify the pathological features of ARVC that would include potential risk of sudden cardiac death during sport or, to avoid the false diagnosis of ARVC. The most recent expert assessment of arrhythmogenic cardiomyopathy focuses on endurance athletes presenting with clinical features indistinguishable from ARVC.     

Arrhythmogenic ventricular cardiomyopathy:A paradigm shift from right to biventricular disease

Arrhythmogenic ventricular cardiomyopathy(AVC) isgenerally referred to as arrhythmogenic right ventricu-lar(RV) cardiomyopathy/dysplasia and constitutesan inherited cardiomyopathy.Affected patients maysuccumb to sudden cardiac death(SCD),ventriculartachyarrhythmias(VTA) and heart failure.Geneticstudies have identified causative mutations in genesencoding proteins of the intercalated disk that lead toreduced myocardial electro-mechanical stability.Theterm arrhythmogenic RV cardiomyopathy is somewhatmisleading as biventricular involvement or isolated leftventricular(LV) involvement may be present and thus abroader term such as AVC should be preferred.The di-agnosis is established on a point score basis accordingto the revised 2010 task force criteria utilizing imagingmodalities,demonstrating fibrous replacement throughbiopsy,electrocardiographic abnormalities,ventricu-lar arrhythmias and a positive family history includingidentification of genetic mutations.Although severarisk factors for SCD such as previous cardiac arrest,syncope,documented VTA,severe RV/LV dysfunctionand young age at manifestation have been identified,risk stratification still needs improvement,especially inasymptomatic family members.Particularly,the roleof genetic testing and environmental factors has to befurther elucidated.Therapeutic interventions include re-striction from physical exercise,beta-blockers,sotalol,amiodarone,implantable cardioverter-defibrillators andcatheter ablation.Life-long follow-up is warranted insymptomatic patients,but also asymptomatic carriersof pathogenic mutations.     

Should Primary Prevention ICDs Still Be Placed in Patients with Non-ischemic Cardiomyopathy? A Review of the Evidence

Purpose of Review

Recent evidence has suggested that implantable defibrillator (ICD) in non-ischemic cardiomyopathy (NICM) may not offer mortality benefit in the presence of guideline-directed medical therapy (GDMT) and cardiac resynchronization therapy (CRT).

Recent Findings

Despite significant benefits of GDMT and CRT, current evidence is derived from ICD trials that rely predominantly on reduced left ventricular ejection fraction alone (LVEF). The majority of patients with sudden cardiac death (SCD) have LVEF >?30% indicating that LVEF by itself is an inadequate predictor of SCD. The Danish study to assess the efficacy of ICD in patients with non-ischemic systolic heart failure on mortality (DANISH) highlights the importance of better risk stratifying NICM patients for ICD implantation.

Summary

Assessment of life expectancy, comorbidities, presence of advanced heart failure, etiology of NICM, and the presence of myocardial fibrosis can help risk stratify ICD beyond LVEF. Genetics and biomarkers can be of further assistance in risk stratification.

     

Predicting Sudden Cardiac Death in Genetic Heart Disease

Genetic heart diseases are common causes of sudden cardiac death (SCD) in the young and are typically divided into inherited cardiomyopathies and primary electrical heart diseases. Cardiomyopathies associated with risk of SCD include hypertrophic cardiomyopathy (HCM) and arrhythmogenic cardiomyopathy (ACM). The latter includes arrhythmogenic right ventricular cardiomyopathy (ARVC) as well as ACM primarily affecting the left ventricle, such as lamin cardiomyopathy. Primary electrical diseases more commonly seen in clinical practice include Brugada syndrome (BrS) and long QT syndrome (LQTS). Risk stratification of SCD is a central component of the management of patients with these genetic heart diseases. Numerous risk factors have been identified with variable degrees of scientific evidence. More recently, risk prediction models have been developed to estimate the absolute risk of sustained arrhythmias and SCD, to support clinicians and patients in decision making regarding prophylactic implantable cardioverter-defibrillators (ICDs). This paper provides a practical review of the current literature on risk stratification in ARVC and other ACMs, HCM, BrS, and LQTS, and summarises current recommendations for ICD use.     

碎裂 QRS 波和心脏性猝死相关性的研究进展

碎裂 QRS 波（fragmented QRS complex,fQRS）的形成机制被认为是心肌瘢痕造成的传导延迟所致,常见于冠心病、心肌梗死患者,也可见于心肌病和先天性心脏病患者。fQRS 对致心律失常性右室心肌病的预测及防治、Brugada 综合征和非缺血性心肌病的预警均具有重要的临床价值。鉴于目前心源性猝死（sudden cardiac death,SCD）危险分层的主要危险因素及预测参数存在明显的局限性,探索新的无创性心电学检查手段成为亟待解决的问题。fQRS 可考虑作为 SCD 危险分层或积分的重要组成部分之一。     

Catheter ablation of ventricular tachycardia in ischaemic and non-ischaemic cardiomyopathy: where are we today? A clinical review

According to the current guidelines, patients with ischaemic cardiomyopathy (ICM) or non-ischaemic cardiomyopathy (NICM) at risk for sudden cardiac death should undergo implantation of an implantable cardioverter-defibrillator (ICD). Although ICDs effectively terminate ventricular arrhythmias, the arrhythmogenic substrate remains unchanged or may progress over time, resulting in recurrent ICD shocks. Defibrillator shocks increase mortality and worsen quality of life. Evidence from two prospective randomized trials on outcome in patients with ischaemic heart disease undergoing catheter ablation for ventricular tachycardia (VT) suggests that ablation prevents recurrence of VT and decreases the number of ICD shocks. This review will highlight the recent progress made in the ablative treatment of VT in patients with ICM and NICM.     

Baseline scintigraphic abnormalities by myocardial perfusion imaging predict echocardiographic response to cardiac resynchronization therapy in nonischemic cardiomyopathy

BACKGROUND: Significant myocardial scar in the posterolateral left ventricle (LV) has been associated with a diminished response to cardiac resynchronization therapy (CRT) in patients with coronary artery disease, but the effects of resting perfusion abnormalities in nonischemic cardiomyopathy (NICM) are yet to be described. HYPOTHESIS: We sought to characterize the effect of myocardial perfusion abnormalities upon echocardiographic outcomes of CRT in patients with NICM. METHODS: Twenty-one patients (mean age 64.4 +/- 13.3; 71.4% male; mean left ventricular ejection fraction [LVEF] 20.2 +/- 6.9%) with NICM who underwent CRT implantation and Thallium-201 single positron emission computed tomography (SPECT) myocardial perfusion imaging (MPI) were included. MPI studies were read quantitatively, assigning each of 17 myocardial segments a perfusion score (0-4) and cumulatively generating a summed perfusion score (SPS). The LV lead position was determined by chest radiography. Echocardiograms were performed both before and after (median 12 mo) CRT in 15 patients. RESULTS: Echocardiographic response, defined as > or = 15% relative increase in LVEF, was documented in 8 (53.3%) of 15 patients. All patients (5/5) with an SP < or =6 responded to CRT, whereas only 30.0% (3/10) with an SPS > or = 6 responded (odds ratio 3.33 [95% confidence interval {CI} 1.29-8.59]; p = 0.01). All nonresponders had inferior perfusion defects. Defect density adjacent to the LV lead tip had little demonstrable effect upon CRT efficacy. CONCLUSIONS: The presence of significant myocardial perfusion defects negatively influences echocardiographic response to CRT in NICM. These findings warrant prospective confirmation and histopathological correlation with explanted hearts.     

左心室射血分数在心脏性猝死危险分层中的价值

心脏性猝死是世界上发达国家中最常见的死因,因此有效的识别高危患者并进行积极有效的预防和治疗有着重要意义。现有多项临床试验表明,左心室射血分数与心脏性猝死有密切关系,其在识别心脏性猝死高危人群及埋藏式心律转复除颤器植入对象的筛选中将具有重要的价值。     

Risk factors for sudden cardiac death to determine high risk patients in specific patient populations that may benefit from a wearable defibrillator

BACKGROUND There is a high risk for sudden cardiac death(SCD) in certain patient groups that would not meet criteria for implantable cardioverter defibrillator(ICD) therapy.In conditions such as hypertrophic cardiomyopathy(HCM) there are clear risk scores that help define patients who are high risk for SCD and would benefit from ICD therapy. There are however many areas of uncertainty such as certain patients post myocardial infarction(MI). These patients are high risk for SCD but there is no clear tool for risk stratifying such patients.AIM To assess risk factors for sudden cardiac death in major cardiac disorders and to help select patients who might benefit from Wearable cardiac defibrillators(WCD).METHODS A literature search was performed looking for risk factors for SCD in patients post-MI, patients with left ventricular systolic dysfunction(LVSD), HCM, long QT syndrome(LQTS). There were 41 studies included and risk factors and the relative risks for SCD were compiled in table form.RESULTS We extracted data on relative risk for SCD of specific variables such as age,gender, ejection fraction. The greatest risk factors for SCD in post MI patients was the presence of diabetes [Hazard ratio(HR) 1.90-3.80], in patient with LVSD was ventricular tachycardia(Relative risk 3.50), in LQTS was a prolonged QTc(HR36.53) and in patients with HCM was LVH greater than 20 mm(HR 3.10). A proportion of patients currently not suitable for ICD might benefit from a WCDCONCLUSION There is a very high risk of SCD post MI, in patients with LVSD, HCM and LQTS even in those who do not meet criteria for ICD implantation. These patients may be candidates for a WCD. The development of more sensitive risk calculators to predict SCD is necessary in these patients to help guide treatment.     

Long‐term outcomes after prophylactic ICD and CRT‐D implantation in nonischemic patients: Analysis from a nationwide database of daily remote‐monitoring transmissions

Introduction: Clinical trials did not provide conclusive evidence concerning the benefit of prophylactic implantable cardioverter‐defibrillators (ICDs) in patients with severe nonischemic cardiomyopathy (NICM). We aimed to compare incidence of appropriate sustained ventricular arrhythmia (SVA) and device therapy in ischemic cardiomyopathy (ICM) vs NICM ICD and/or cardiac resynchronization therapy (CRT‐D) patients. Methods and Results: We analyzed remote‐monitoring data from devices of the Home Monitoring Expert Alliance network. SVA recordings were adjudicated by three independent electrophysiologists. Our cohort included 1,946 patients who received either an ICD (55%) or a CRT‐D (45%) for primary prevention of sudden cardiac death. Median (interquartile range) age was 70 (62‐77) years, 81% were male, and 52% were in the ICM group. Patients were remotely monitored for a maximum follow‐up of 5 years. The 5‐year product‐limit estimate of SVA incidence in patients with an ICD was 47.3% (95% confidence interval [CI], 41.0%‐53.9%) in the ICM group and 44.7% (36.9%‐53.3%) in the NICM group. In patients with a CRT‐D, SVA incidence was 45.7% (37.3%‐55.0%) in ICM patients and 49.2% (40.4%‐58.7%) in NICM patients. The adjusted hazard ratio for SVA in the ICM vs NICM group was 0.96 (95% CI: 0.70‐1.30, P = .77) in ICD patients and 0.85 (95% CI: 0.61‐1.18, P = .34) in CRT‐D patients. SVAs triggered appropriate device therapies with similar incidence in all groups. Conclusion: In a large cohort of remotely monitored ICD and CRT‐D recipients, SVA incidence did not significantly differ in ICM and NICM patients.     

Sudden death related cardiomyopathies – Arrhythmogenic right ventricular cardiomyopathy,arrhythmogenic cardiomyopathy,and exercise-induced cardiomyopathy

Sudden cardiac death (SCD) is a devastating possible outcome of all cardiomyopathies. The risk of SCD is increased in patients with structural heart disease and continues to increase as ventricular dysfunction worsens. There is, however, a subset of cardiomyopathy, so-called “arrhythmogenic cardiomyopathy” (ACM), that carries an inherent propensity for arrhythmia in all stages of the disease, even preceding ventricular dysfunction. The aim of this review is to identify cardiomyopathies, other than ischemic and dilated cardiomyopathies, that are associated with ventricular arrhythmias (VAs) and SCD. We discuss prevalence, diagnosis, natural history and management of arrhythmogenic right ventricular dysplasia/cardiomyopathy, ACM, and exercise-induced cardiomyopathy, with emphasis on the morbidity and mortality of VAs associated with these cardiomyopathies and how they can be mitigated through lifestyle modification, medical management, and implantation of cardioverter defibrillators.     

Apical hypertrophic cardiomyopathy: A case series at a Brazilian referral center with a maximal follow-up of 15 years

BackgroundApical hypertrophic cardiomyopathy (AHCM) is a rare cardiomyopathy, in which hypertrophy occurs predominantly in the ventricular apex, and in some cases with a high risk of sudden cardiac death.ObjectiveThe aim of this paper is to present a case series of patients with AHCM and describe their main clinical, echocardiographic and electrocardiographic characteristics, the recommendation for an implantable cardioverter-defibrillator (ICD) and the frequency of sudden cardiac death (SCD).MethodsA retrospective case series was conducted at the referral center of a federal teaching hospital, between the years 2005 to 2020, involving patients with an echocardiographic diagnosis of AHCM. The parameters of the American College of Cardiology and the European Society of Cardiology were used to assess the risk of SCD.ResultsA total of 11 individuals were assessed with a mean age of 55.3 years, mean follow-up of 41.2 months, most of whom were symptomatic at diagnosis (72.7%). The most frequent symptom was dyspnea (27.3%). A family history of SCD was described in 45.5% of cases. Due to a high risk of SCD, four patients received ICDs. One patient presented sudden cardiac death after having refused the ICD.ConclusionsSymptoms and alterations in the imaging exams are significant factors in the clinical and prognostic assessment of patients with AHCM.     

Sinus rhythm ECG criteria associated with basal-lateral ventricular tachycardia substrate in patients with nonischemic cardiomyopathy

ECG Criteria Associated with NICM VT . Introduction: Patients with nonischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) usually have basal‐lateral scar in the left ventricle (LV). We sought to determine electrocardiogram (ECG) characteristics that may help identify NICM patients with basal‐lateral scar and VT. Methods and Results: Phase I, study patients (n = 25) had NICM, VT, and endocardial/epicardial basal‐lateral LV low voltage consistent with scar on detailed mapping. ECGs were compared to controls (n = 18) with NICM, and comparable age and gender without VT/known scar. All patients had either sinus or paced atrial rhythm ECGs without bundle‐branch block or ventricular pacing. In phase II, criteria were evaluated prospectively, blinded to clinical data, using ECGs from 15 NICM patients, of which 7 patients had VT and endocardial/epicardial basal‐lateral LV scar on detailed mapping. Of ECG characteristics studied, V1 R and R:S ratio, and V6 S and S:R ratio were univariately associated with basal‐lateral‐scar associated VT. Controlling for LVEF and multicollinearity in multivariate analyses, V1 R ≥ 0.15 mV (P = 0.001) and V6 S ≥ 0.15 mV (P < 0.001), or V6 S:R ≥ 0.2 mV (P < 0.001), best predicted presence of basal‐lateral scar. In Phase II, the former criteria best identified those with NICM and VT because of basal‐lateral scar, with sensitivity and specificity 0.86 and 0.88, respectively. Conclusions: Among patients with NICM, VT, and normal QRS duration, V1 R ≥ 0.15 mV and V6 S ≥ 0.15 mV predicted presence of basal‐lateral LV areas of bipolar low voltage. This ECG information may have important value in defining presence of LV scar and possible risk for VT in NICM patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1351‐1358, December 2011)     

扩张型心肌病临床与预后的关系探讨

目的 :探讨扩张型心肌病(DCM )发生心脏性猝死 (SCD)的高危因素 ,研究DCM临床与预后的关系。方法 :对 60例DCM临床资料进行分析 ,以超声心动图 (UCG)、心电图 (ECG)、动态心电图 (DCG、Holter)及X线胸片观察心脏各参数变化 ,并做心电图QT离散度 (QTd)测定。结果 :有病毒性心肌炎病史与无病毒性心肌炎病史病人 ,重度心力衰竭、严重室性心律失常的发生率分别为 66.7%和 2 3 .3 % ,经比较有统计学意义 (P <0 .0 5 ) ;5例SCD均有病毒性心肌炎史 ,临死前都发生多次严重室性心律失常、晕厥 ;QTd对预测SCD高危因素有意义。结论 :有病毒性心肌炎史、心力衰竭、严重室性心律失常、头晕或晕厥及QTd增加 ,可作为预测发生SCD的高危因素。     

18例非缺血性心肌病临床诊疗体会

目的：研究非缺血性心肌病（NICM）患者血清学指标、辅助检查指标与患者不良终点发生的关系。方法纳入2004年1月~2011年10月南京医科大学第二附属医院NICM患者18例，其中4例患者院内死亡，进入死亡组，其余14例患者进入存活组。采用酶联免疫吸附测定（ELISA）法对脑钠肽（BNP）、心脏肌动蛋白（cTnI）、肌红蛋白（MYO）进行检测，同时对两组患者住院期间NYHA心功能分级、心率（HR）、平均动脉压（MAP）、左心射血分数（LVEF）、心胸比等指标进行比较。结果与存活组相比，死亡组住院期间MBP明显较低[（78±15）mmHg vs.（87±15）mmHg，P＜0.05]，LVEF值下降[（28.3±7.2）%vs.（32.2±7.4）%，P＜0.05]，血清BNP明显升高[（2231±556）pg/ml vs.（647±231）pg/ml，P＜0.05]。结论非缺血性心肌病患者血清BNP升高、LVEF值明显下降以及cTnI轻微升高可提示患者不良事件高发风险。