Sudden Cardiac Death in China

Preliminary data suggest that sudden cardiac death (SCD) occur at a rate of 41.8/100,000 population in China, accounting for over 544,000 deaths annually. While about 70% of SCD are due to underlying coronary artery disease, several specific cardiomyopathies and hereditary heart diseases are endemic in China. Pharmacological treatment is the main treatment strategy, and both community resuscitation and implantable cardioverter defibrillator therapy are limited by socioeconomic conditions. There is increasing use of catheter ablation for some ventricular arrhythmias. A national project has been started recently for SCD prevention.     

心脏性猝死高危因素探析

目的 :探讨与心脏性猝死相关的危险因素。方法 :对 46例心脏性猝死的临床资料进行回顾性分析研究。结果 :男性 2 6例 ,女性 2 0例 ,男性中吸烟者 2 1例 ;心脏扩大及心功能Ⅲ～Ⅳ 36例 ;有心电图记录者 37例均显示异常 ,其中室性心律失常 39例次 ,左室肥厚伴ST T改变 12例 ;12例     

Implantable Cardioverter Defibrillator Therapy for Prevention of Sudden Cardiac Death in Children in The Netherlands

Introduction: Implantable cardioverter defibrillator (ICD) therapy is increasingly used in children. The purpose of this multicenter study is to evaluate mid‐term clinical outcome and to identify predictors for device discharge in pediatric ICD recipients. Methods and Results: From 1995 to 2006, 45 patients in The Netherlands under the age of 18 years received an ICD. Mean age at implantation was 10.8 ± 5.2 years. Primary prevention (N = 22) and secondary prevention (N = 23) were equally distributed. Underlying cardiac disorders were primary electrical disease (55%), cardiomyopathy (20%), and congenital heart disease (17%). The follow‐up was 44 ± 32.9 months. Three patients (7%) died and one patient (2%) underwent heart transplantation. ICD‐related complications occurred in eight patients (17%), seven of whom had lead‐related complications. Fourteen patients (31%) received appropriate ICD shocks; 12 patients (27%) received inappropriate ICD shocks. Fifty‐five percent of 22 ICD recipients under the age of 12 years received appropriate shocks, which was higher as compared with 9% of 23 older ICD recipients (P = 0.003). Although the incidence of appropriate shocks in the present study was larger in secondary prevention (9/23; 39%) as compared with primary prevention (5/22; 23%), this difference did not reach significance. Conclusions: In our population of patients, children <12 years of age had more appropriate shocks than patients 13–18 years. The complication rate is low, and is mainly lead related. (PACE 2010; 33:179–185)     

Sudden Cardiac Death, Implanted Defibrillation, and Clinical Electrophysiology

A mere 25 years ago, the technique of external defibrillation became the starting point for the development of clinical electrophysiology by permitting routine use of endocavitary programmed electrical stimulation of the heart without undue risk. Major advances in knowledge of clinical arrhythmias and the understanding of their mechanisms were, thus, permitted. Mirowski's implanted defibrillator also constituted a major breakthrough therapeutically; unfortunately, however, some 10 years later, it has not yet induced similarly hoped for consequences in terms of progressing knowledge concerning lethal arrhythmias, largely due to the absence of Holter functions in the implanted devices. As a result of this, in our opinion, better established therapeutic indications are still needed. The reasons for the present situation, we believe, may be partly technical but are conceptual as well. The key point is that even the clear demonstration of the great practical efficacy of a therapeutic tool does not exempt us from the obligation of determining the mechanisms of this effect.     

Epidemiology of Ventricular Tachycardia/Ventricular Fibrillation and Sudden Cardiac Death

Despite the difficulties correlating pathological data with acute clinical events in the field of sudden cardiac death, information useful to both the clinician and the epidemiologist has developed. Sudden cardiac death may be defined broadly. These definitions have varied, but it is now generally recognized that sudden cardiac death should reflect a time span of less than one hour. The epidemiology of sudden cardiac death incorporates many factors, including age, heredity, gender, and race. Coronary risk factors and the history of prior coronary heart disease constitute additional points of importance. Finally, clinical characteristics of the cardiac arrest patient are variable. Improving outcome in prehospital cardiac arrest victims involves a multifactorial approach involving rescue personnel, resuscitation technology, and the participation of the public.     

胃食管电极心室起博抢救心脏性猝死的临床应用

目的 :探讨胃食管电极心室起搏抢救心脏性猝死的临床应用。方法 :以 18例急重症缓慢型心律失常引起的心脏性猝死 ,进行 18例次胃食管电极心室起搏。结果 :16例 (88.9% )起搏成功。其中 15例 (83.3 % )起搏脉宽 40msec ,阈值 2 2 .1± 8.7V ;1例脉宽 10msec ,阈值 32V。结论 :体会有 3点优点 :①心室夺获率高 ,阈值电压低 ;②操作非创伤性、安全、方便、快速 ;③不需中断心肺复苏术 (CPR)的持续进行。     

Risk Assessment and Risk Stratification in Sudden Cardiac Death: A Biostatistician's View

Determining individual probabilities of developing lethal arrhythmia over time (risk assessment) and grouping individuals by that probability (risk stratification) are similar to, yet differ in purpose from, screening, diagnosis, risk factor identification, and prognostic staging. Methods of handling bias, use of multiple predictors, and evaluation of results provide challenges. A key purpose of risk assessment and stratification is examined. The role of operational definitions of predictors and events and of methods that account for multiple predictors and known confounding factors is analyzed. Constructed examples illustrate potential pitfalls in assessment and how multivariate techniques can deal with multiple predictors. A trial design to evaluate risk stratification for the identified purpose is elaborated and potential results are interpreted. Bias from predictors regressing to the mean can be minimized either by averaging a number of measurements or by equalizing the bias in comparison groups. An analysis of two predictors and two risk strata illustrates how the discrimination of combined predictors may be greater than the sum of the individual variables' discrimination. Risk stratification can be evaluated in trials that randomize competing interventions within different risk strata. Results of such trials indicate whether the risk strata adequately distinguish individuals by their responsiveness to particular intervention. Potential pitfalls, not easily recognized in risk stratification, can be avoided in the methods and in studies for evaluating those methods. Multivariate techniques maximize the discrimination of multiple predictors, but may increase complexity. Randomized trials of treatment provide evidence for utility of risk stratification.     

QT Dynamics and the Risk of Sudden Arrhythmic Cardiac Death in Ischemic Heart Disease

The relationship between altered QT dynamics and the risk of sudden arrhythmic death has not been established so far. This article describes the behavior of QT dynamics assessed in a patient with ischemic heart disease after two documented cardiac arrests due to sustained ventricular arrhythmia. (PACE 2004; 27[Pt. I]:827–828)     

Drug Therapy for Survivors of Sudden Cardiac Death

The proliferation of standard as well as novel community based systems for resuscitation of victims of out-of-hospital cardiac arrest has provided a large group of sudden cardiac death survivors who present a therapeutic challenge. The nature and severity of the underlying heart disease must be delineated. Particularly, myocardial ischemia and congestive heart failure must be controlled. Prior to considering device therapy of surgical intervention, pharmacologic therapy should be evaluated. Baseline electrophysiological studies determine the applicability of serial pharmacologic testing. In patients with inducible VT/VF, serial electrophysiological testing can identify drug regimens that prevent the arrhythmia in approximately 40% of patients. In an additional 20% of patients, regimens which slow the ventricular tachycardia and significantly reduce the arrhythmia related mortality can be identified. Three to 5-year follow-up has shown such an approach can reduce the sudden death mortality in these patients to less than 3% per year. It has been suggested that certain medication, most notably amiodarone, electrophysiological testing has not been useful in assessing efficacy. Several recent studies, however, have shown that electrophysiological testing is indeed useful even in evaluating the efficacy of amiodarone. In patients in whom ventricular tachycardia/ventricular fibrillation cannot be prevented or significantly slowed, medical therapy is generally ineffective and the sudden death mortality is 20% to 40% per year. In such patients, other therapeutic modalities should be considered.     

心源性猝死的病因、诱因及预防——附178例法医病理学解剖分析

目的:探讨心源性猝死(SCD)不同年龄、性别的病因、诱因特点及相关预防措施。方法:对2000～2005年在四川华西法医学鉴定中心进行尸体解剖的178例SCD案例资料进行回顾性分析。研究SCD与年龄、性别、诱因、潜伏病变的关系,并提出预防措施。结果:本组资料显示,精神性因素、过度劳累、轻微外伤在各类诱因中所占比例较高,不同年龄组潜伏病变有差别。负性生活事件可看作SCD一个潜在的诱因,在不同性别与年龄组中起着不同的作用。结论:心源性猝死多数有诱因或伴发于负性生活事件,减少此类事件的发生对预防心源性猝死有一定帮助。     

Implantable Cardioverter Defibrillator Therapy for Primary Prevention of Sudden Cardiac Death after Myocardial Infarction:

Study Objective: To estimate the proportion of patients eligible for implantable cardioverter defibrillator (ICD) therapy for the primary prevention of sudden cardiac death after a myocardial infarction (MI), according to the current guidelines.
Methods: Eligibility was assessed retrospectively at 6 weeks in 513 post-MI survivors (age 66 ± 13 years, left ventricular ejection fraction 48.2 ± 17%) on the basis of an electrocardiogram and an echocardiogram.
Results: LVEF was ≤ 40% in 37% and ≤ 35% in 30%, and QRS duration was <120 ms in 89% and ≥120 ms in 11% of patients. The proportion of post-MI patients meeting the criteria set by guidelines were 37% for 2006 American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) 26.5% for 2008 ACC/AHA/Canadian Heart Rhythm Society 16.3% for 2005 US Centers for Medicare and Medicaid Services (CMS), and 5.8% for the 2006 United Kingdom (UK) National Institute of Clinical Excellence (NICE). According to 2005 CMS and 2006 UK-NICE guidelines, Holter monitoring was required in 7% and 18%, respectively. For the United States (700,000 MI in 2006), the 2006 ACC/AHA/ESC guidelines equate to 216,783 ICD implantations/year. For UK (60,499 MI in 2006), the 2006 NICE guidelines equate to 2,941 ICD implantations, 10,488 Holter studies, and 1,065 VT induction tests/year.
Conclusions: Current ICD therapy guidelines for primary prevention of SCD post-MI demand a substantial increase in service provision worldwide.     

Sinus Node Dysfunction and Sudden Cardiac Death Following Treatment with Encainide

Encainide, a class Ic drug, is generally thought of as having little effect on sinus node function. In this article, we present the clinical course and electrophysiological findings of a patient who had cardiac arrest after 1 week of encainide therapy for ventricular extrasystoles. No ventricular tachyarrhythmias were induced during programmed ventricular stimulation (baseline study and while receiving encainide therapy). Prior to encainide therapy, sinus node function was normal, but clinical observations after admission for cardiac arrest and subsequent electrophysiological study revealed that encainide had caused striking impairments in sinus node function. During a 6-month follow-up without antiarrhythmic drug treatment, this patient has had an uneventful course. We concluded that encainide can cause severe and life-threatening sinus node dysfunction.     

Incidence and Characteristics of Appropriate and Inappropriate Therapies in Recipients of ICD Implanted for Primary Prevention of Sudden Cardiac Death

Background: We evaluated the number of appropriate and inappropriate therapies for ventricular tachyarrhythmias and trigger mechanisms in 55 MADIT II (MII)-like (group 1) and 86 SCD-HeFT-like (group 2) patients.
Methods and Results: We analyzed 399 appropriate episodes in 31 patients with implantable cardioverter defibrillators (ICD) implanted according to the MII trial indications, and 502 appropriate episodes in 47 patients matching the SCD-HeFT trial criteria (mean follow-up in both groups = 33 ± 19 months). In group 1, 39 treated episodes were inappropriate (9% of all episodes), while in group 2, 76 episodes were treated inappropriately (15% of all episodes). At least one episode of inappropriate ICD therapy was recorded in 18% of patients in group 1 (n = 10) and in 22% of patients in group 2 (n = 19).
Conclusions: Our study supports the implantation of ICD as primary prevention in patients who are at risk of sudden cardiac death, although the proportion of inappropriate ICD interventions remains high.     

自主神经功能指标对心脏性猝死的预测价值

目的探讨自主神经功能指标（心率变异性及心率震荡）对心脏性猝死（SCD）患者的预测价值。方法对江西省人民医院门诊及住院的50例猝死高危患者（猝死高危组）进行前瞻性随访研究,同时选择无明显器质性心脏病史的患者50例作为对照组。2组患者均采用24h动态心电图进行检测,分析心率变异性的24h正常窦性RR间期的标准差时域指标（SDNN）、窦性心率震荡的心率起始（TO）和心率斜率（TS）指标的变化,3个月随访1次,持续2年。猝死高危组根据是否发生终点事件分为恶性心律失常组（12例）及非恶性心律失常组（38例）。以SCD或室颤作为终点事件,对上述数据进行统计学分析。结果猝死高危组中12例患者发生SCD（冠心病6例,扩张性心脏病5例,长QT综合征1例）。猝死高危组SDNN、TS均明显低于对照组,TO高于对照组（均P〈0．05）。恶性心律失常组的TS明显低于非恶性心律失常组（P〈0．05）;2组SDNN及TO比较差异均无统计学意义（均P〉0．05）。结论猝死高危患者TS低于对照组,且与恶性心律失常的发生关系密切。TS可能是SCD预测的重要指标。     

The Effect of Coronary Bypass Graft Surgery for the Prevention of Sudden Cardiac Death: Recurrent Episodes After ICD Implantation and Review of Literature

Sudden cardiac death (SCD) accounts for at least 50% of the mortality of patients with ischemic heart failure. Ventricular arrhythmias are responsible for most cases of sudden cardiac death. There is some evidence that coronary artery bypass graft (CABG) surgery may reduce the incidence of recurrent episodes of SCD by prevention of myocardial ischemia. To test the hypothesis that CABG surgery is effective in the prevention of SCD, we compared the recordings of implantable cardioverter defibrillators (ICD) in patients who underwent ICD implantation alone (n = 64) or ICD implantation and concomitant CABG surgery respectively (n = 11). All patients had experienced out of hospital cardiac arrest. ICD recordings were obtained every 3 months and the number of recurrent episodes of ventricular tachycardia (VT) for each time period was noted. Three months foilowing ICD implantation patients in the surgically treated group had an average of one episode of VT per patient as compared to 2.7 episodes in the nonsurgical group. This difference was observed during the following months as well. However, at nlo time (up to 18 months of follow-up) this difference reached statistical significance. There were no deaths in the surgically treated group. Although we could not demonstrate a statistical significant difference between the two groups, there was a tendency in the surgically treated group to have less episodes of recurrent VT than in the medically treated group. We, therefore, conclude that survivors of SCD presenting with multivessel coronary artery disease (CAD) should undergo coronary artery bypass grafting to prevent myocardial ischemia as the triggering event for lethal ventricular arrhythmias.     

Cardiac Arrest and Sudden Death in Competitive Athletes with Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a predisposing factor for sportrelated cardiac arrest (CA), sudden cardiac death (SD). and life-threatening ventricular tachyarrhythmias (VT). The aim of this study was the assessment of athletes with ARVD, particularly the CA survivors. From 1974 to January 1996, 1642 competitive athletes (aver. 25.5 yr.), 136 of whom were top level athletes (TLA), were studied for important arrhythmic manifestations. All athletes underwent an individualised study protocol including a series of non invasive and invasive diagnostic techniques. One hundred and one athletes (90 males, 11 females, aver. 25.9 yr.) were diagnosed as being affected by ARVD on the basis of the WHO/ISFC criteria. The same percentage (about 6%) of ARVD is present in both the general arrhythmic athletes population and in the subgroup of TLA. Prevalence of ARVD among athletes with CA or SD is high (respectively 23% and 25%), confirming the observation that ARVD is one of the major causes of SD in Italian athletes. All CA were athletic activity related, indicating the potentiality of exercise as a cause of electrical destabilisation in subjects with ARVD. In athletes with documented ARVD intense sport activity has to be proscribed. In athletes at risk of CA or SD an aggressive treatment, ICD implantation and RF catheter ablation must be taken into consideration.     

Low‐Risk Profile for Malignant Ventricular Arrhythmias and Sudden Cardiac Death after Surgical Ventricular Reconstruction

Background: Although it has been recently demonstrated that there was no significant difference in total survival and clinical outcomes between patients who underwent coronary artery bypass grafting (CABG) with or without surgical ventricular reconstruction (SVR), the question of whether or not SVR decreases the arrhythmic risk profile in this population has not been clarified yet. Objective: To determine the real incidence of sudden cardiac death (SCD) and sustained ventricular tachycardia/ventricular fibrillation (sustained VT/VF) in patients following CABG added to SVR and to define their clinical and echocardiographic parameters predicting in‐hospital and long‐term arrhythmic events (SCD + sustained VT/VF). Methods: Pre‐ and postoperative clinical and echocardiographic values as well as postoperative electrocardiogram Holter data of 65 patients (21 female, 63 ± 11 years) who underwent SVR + CABG were retrospectively evaluated. Results: Mean follow‐up was 1,105 ± 940 days. At 3 years, the SCD‐free rate was 98% and the rate free from arrhythmic events was 88%. Multivariate logistic analysis identified a preoperative left ventricular end‐systolic volume index (LVESVI) > 102 mL/m² (odds ratio [OR] 1.4, confidence interval [CI] 1.073–1.864, P = 0.02; sensitivity 100%, specificity 94%) and a postoperative pulmonary artery systolic pressure (PASP) > 27 mmHg (OR 2.3, CI 1.887–4.487, P = 0.01; sensitivity 100%, specificity 71%) as independent predictors of arrhythmic events. Conclusions: Our and previous studies report a low incidence of arrhythmic events in patients following SVR added to CABG, considering the high‐risk profile of the study population. A preoperative LVESVI > 102 mL/m² and a postoperative PASP > 27 mmHg had a good sensitivity and specificity in predicting arrhythmic events. (PACE 2010; 33:1054–1062)     

Primary Prevention of Sudden Cardiac Death: Can We Afford the Cost of Cardioverter-Defibrillators? Data from the Search-MI Registry-Italian Sub-study

Background: Large randomized trials show that in appropriately selected patients with left ventricular dysfunction, implantable cardioverter-defibrillators (ICDs) can improve overall survival at 2–5 years. Since direct implementation of the criteria used in the MADIT II and SCD-HeFT will lead to a marked rise in ICD implants, there is a growing fear that increased use of ICDs may cause a dramatic burden to health care systems. The ICD has traditionally been seen as an expensive form of treatment, which is difficult to accept at the first look. This is mainly due to the nonlinear character of the ICD investment, characterized by high initial expenditure, followed by a deferred pay-off in terms of clinical benefits. Cost-effectiveness analysis may help provide a different perspective on the problem of ICD cost, as may estimation of the daily cost of ICD treatment, assuming a time horizon of 5–7 years—a particularly interesting subject for further registry studies.
Methods and Results: Based on real expenditure data from 2002 to 2005, as recorded in the Search-MI Registry-Italian Sub-study of patients implanted on MADIT II indications, we estimated the daily costs associated with the device and leads. Over a 5–7 year time horizon, the average daily cost was estimated to be €4.60–€6.70. Translation of these figures into U.S. market conditions suggests a daily cost of around $7.90–$11.40.
Conclusions: These findings appear useful to help evaluate the affordability of ICD in comparison with other therapeutic options in a context of limited available economic resources.     

Sudden Cardiac Death in a Southeast Asian Immigrant: Clinical, Electrophysiologic, and Biopsy Characteristics

The syndrome of sudden cardiac death in southeast Asians has only recently been given attention in the American medical literature. This case report describes a patient who presented with this rare syndrome. The physical examination, Holter monitor. 2-D echocardiogram, exercise treadmill test, radionuclide ventriculogram, coronary angiography, and endomyocardial biopsy were all normal. Programmed ventricular stimulation reproducibly induced sustained polymorphic ventricular tachycardia, Oral procainamide, oral quinidine and oral quinidine plus propranolol were not successful in suppressing inducible polymorphic ventricular tachycardia. The arrhythmia remained inducible after six weeks of oral amiodarone therapy. However, he has had no clinical recurrences while on amiodarone after one year of follow-up.