Identification of persons at risk for sudden cardiac death

Before any more progress is made in reducing the incidence of sudden cardiac death, our ability to identify those at risk must be refined further. The close association with coronary artery disease necessitates that the first step must be the identification of those with underlying coronary artery disease. This is underscored by the disturbing fact that, in many, sudden death is the first sign of coronary disease. An aggressive evaluation of those with significant risk factors appears justified. The second part of the problem is the identification of those with coronary artery disease who are at especially high risk. The current diagnostic modalities available suffer from a relative lack of specificity to be applied indiscriminately in light of the expense and morbidity of effective therapies (that is, coronary artery bypass surgery, antiarrhythmic drugs, implantable defibrillators, surgical or catheter ablation). At the present time, we can identify certain subsets that warrant aggressive therapy: survivors of sudden death events or sustained ventricular tachycardia, obstructive cardiomyopathies, aortic stenosis, left main coronary artery disease, and congenital QT prolongation. Less aggressive but also less specific therapies, such as beta-blockers in myocardial infarction survivors, can be given more indiscriminately. Ultimately, of course, the greatest impact will come from prevention of coronary artery disease.     

Role of drugs and devices in patients at risk of sudden cardiac death

The search for effective treatment for preventing sudden cardiac death (SCD) initially started with anti‐arrhythmic agents in high‐risk patients, but the use of randomized controlled trials clearly led to the conclusion that an approach based on anti‐arrhythmic agents is not useful, and sometimes potentially harmful (the risk of arrhythmic death was increased up to 159% in CAST study). Today the approach to SCD prevention includes considering both the setting of patients who have already presented a cardiac arrest or a malignant ventricular tachyarrhythmias (secondary preventions of SCD) and the much broader setting of primary prevention in patients at variable degrees of identifiable risk. For secondary prevention of SCD, implantable cardioverter defibrillation is now the standard of care (the risk of overall mortality may be reduced by 20–31%), and anti‐arrhythmic agents, specifically amiodarone, have only a complementary role (for reducing device activations or for preventing atrial fibrillation). For primary prevention of SCD in high‐risk patients, cardioverter defibrillators have nowadays specific indications in patients with left ventricular dysfunction (often in combination with cardiac resynchronization therapy), where the risk of overall mortality may be reduced by 23–54%. For the large number of subjects who have some risk of SCD, but are not identified as at high risk of SCD, a series of drugs could exert a favorable effect (beta‐blockers, angiotensin‐converting enzyme inhibitors, angiotensin receptor blocker agents, statins, omega‐3 fatty acids and aldosterone antagonists), and for some of them evidence is emerging, from subgroup analysis, of possible SCD prevention capabilities.     

Implantable cardioverter defibrillators in diabetics: efficacy and safety in patients at risk of sudden cardiac death

Diabetes mellitus is a major risk factor for arrhythmogenesis and is associated with a two-fold increase in all-cause mortality and a four-fold increase in cardiovascular mortality including sudden cardiac death when compared with nondiabetics. Implantable cardioverter defibrillators (ICD) have been shown to effectively reduce arrhythmic death and all-cause mortality in patients with severe myocardial dysfunction. With a high competing risk of nonarrhythmic cardiac and noncardiac death, survival benefit of ICD in patients with diabetes mellitus could be reduced, but the subanalysis of diabetic patients in randomized clinical trials provides reassurance regarding a similar beneficial survival effect of ICD and cardiac resynchronization therapy in diabetics, as observed in the overall population with advanced heart disease. In this article, the authors highlight some of the clinical issues related to diabetes, summarize the data on the efficacy of ICD in diabetics when compared with nondiabetics and discuss concerns related to ICD implantation in patients with diabetes.     

Cyclic antidepressants and the risk of sudden cardiac death

BACKGROUND: Tricyclic and other related cyclic antidepressants (TCAs), used frequently for the treatment of depression and several other indications, have cardiovascular effects that may increase the risk of sudden cardiac death. We thus sought to quantify the risk of sudden cardiac death among TCA users, according to dose, as well as among users of selective serotonin reuptake inhibitors (SSRIs). METHODS: We conducted a retrospective cohort study in Tennessee Medicaid, from Jan 1, 1988, through Dec 31, 1993, which included large numbers of antidepressant users and computer files describing medication use and comorbidity. The cohort included 1,282,091 person-years of follow-up for persons aged 15 to 84 years who were not in a nursing home and were free of life-threatening noncardiac illness. This included 58,956 person-years for current use of TCAs alone, 6291 person-years for SSRIs only, and 96,220 person-years for former use. RESULTS: The cohort included 1487 confirmed sudden cardiac deaths occurring in the community. When compared with nonusers of antidepressants, current users of TCAs had a dose-related increase in the risk of sudden cardiac death. Rate ratios increased from 0.97 (95% confidence interval [CI], 0.72-1.29) for doses lower than 100 mg (amitriptyline or its equivalent) to 2.53 (95% CI, 1.04-6.12) for doses of 300 mg or more (P =.03, test for dose-response). The rate ratio for SSRIs was 0.95 (95% CI, 0.42-2.15). There was no evidence that TCA doses lower than 100 mg increased the risk of sudden cardiac death in subgroups defined by pre-existing cardiovascular disease, female sex, age 65 years or older, or use of amitriptyline. CONCLUSIONS: Our data suggest that SSRI antidepressants and TCAs in doses of less than 100 mg (amitriptyline equivalents) did not increase the risk of sudden cardiac death. However, higher doses of TCAs were associated with increased relative risk, which suggests that such doses should be used cautiously, particularly in patients with an elevated baseline risk of sudden death.     

探讨心内科老年患者治疗期间心源性猝死的临床危险因素江西省安福县人民医院内一科 曾林飞

目的 分析心内科老年心血管疾病患者发生心源性猝死的高危因素。方法 搜集自2016年2月- 2019年8月在本院心内科住院期间发生心源性猝死的患者共68例,作为研究组;搜集同期未发生心源性猝死的心血管疾病患者共145例,作为对照组。收集并比较两组患者的饮酒史、吸烟史、合并症、BMI、年龄、疾病类型等临床资料,展开回顾性分析,采用Logistic分析影响患者发生心源性猝死的高危因素。结果 研究组患者中心率失常、伴高血压、伴高血脂、伴心肌梗塞病史、伴外伤、便秘、瓣膜心脏病和慢性肺病比例、BMI值明显高于对照组,差异具有统计学的意义(P<0.05);经Logistic分析显示,瓣膜心脏病、高血脂、心肌梗塞病史、慢性肺病、便秘、心率失常、BMI≥28kg/m²均为患者发生心源性猝死的高危因素(P<0.05)。结论 高血脂、心肌梗塞病史、慢性肺病、便秘以及肥胖均会增加老年心血管疾病患者发生心源性猝死的风险性,在治疗时需早期评估心内科老年患者的心源性猝死风险,指导患者调整生活习惯,控制合并症,预防猝死的发生。     

Survivors of acute myocardial infarction: who is at risk for sudden cardiac death?

Coronary artery disease is the leading cause of death in the United States. Approximately half of the deaths attributable to coronary artery disease are sudden cardiac deaths. A logical approach to prevention of sudden death is to identify those who are at risk and then to initiate effective therapy. Left ventricular dysfunction, frequent ventricular ectopic activity, nonsustained ventricular tachycardia, and late potentials have been identified as markers for increased risk of sudden cardiac death. The sensitivity and specificity of these risk factors vary, and the positive predictive power is less than satisfactory. The value of invasive electrophysiologic testing for risk stratification in the general postinfarction patient population remains unclear. In addition to these diagnostic difficulties, prevention of sudden death also has been limited by imperfect efficacy and potential lethal effects of the currently available antiarrhythmic agents. Automatic implantable defibrillators are effective for aborting sudden death; however, the potential for more general use of automatic defibrillators in asymptomatic but high-risk postinfarction patients has not been evaluated.     

心脏性猝死72例高危因素临床探讨

目的 探讨心脏性猝死(SCD)发病的危险因素.方法 以72例心脏性猝死患者的临床资料为研究对象,进行回顾性分析.结果 72例心脏性猝死患者中,男性43例,女性29例,男性中吸烟者29例;心脏扩大伴心功能Ⅲ～Ⅳ级58例;有心电图检查者61例均显示异常,其中室性心律失常65例、左室肥厚伴ST-T改变21例;低钾53例、高钾3例,正常范围9例;胆固醇升高32例,高血压病22例,糖尿病6例.猝死前有诱因者29例.结论 心脏扩大伴心功能Ⅲ～Ⅳ级、左室肥厚伴ST-T改变及室性心律失常是心脏性猝死的高危因素.     

老年心脏性猝死的临床分析

目的：分析老年心脏性猝死（ＳＣＤ）的临床特点。方法：回顾３７例６１～８４岁ＳＣＤ者的临床资料,其中部分患者曾行冠状动脉造影或尸检。结果：老年ＳＣＤ者中８１．１％生前有冠心病,５６．８％患冠心病和高血压２种疾病。冠状动脉造影或尸检可见冠状动脉血管粥样硬化病变广泛、严重。男性和伴有左室功能不全者ＳＣＤ的危险增高。结论：为减少老年冠心病和高血血压患者发生ＳＣＤ,临床需采取积极措施,改善患者心肌缺血,保护心功能。     

Preventing sudden cardiac death

An exciting new era has begun in the management of patients who either have survived or are at risk for lethal ventricular arrhythmias. Electrophysiologic testing, a remarkably safe procedure, can be used to guide selection of the best protective drug regimen. A new device, the automatic implantable cardioverter-defibrillator, continuously monitors the heart rate and converts sustained ventricular tachyarrhythmias to normal sinus rhythm. Drs Lehmann and Steinman anticipate a significant reduction of the death rate in these patients in the coming years.     

Preventing sudden cardiac death

The syndrome of sudden cardiac death, which claims the lives of hundreds of thousands of Americans each year, is usually caused by ventricular tachycardia or fibrillation. Electrophysiologic testing is now being used to prevent recurrence of this syndrome in successfully resuscitated persons. With this procedure, antiarrhythmic drugs are assessed in terms of their ability to prevent induction of sustained ventricular tachyarrhythmias, rather than their ability to merely suppress ventricular premature beats. In medically unresponsive patients, an automatic cardioverter-defibrillator can be implanted to provide maximal protection from sudden cardiac death caused by ventricular tachyarrhythmias.     

Impaired pulmonary function is a risk predictor for sudden cardiac death in men

Abstract

Objectives. Little is known about the association of reduced pulmonary function and the risk of sudden cardiac death (SCD). Our aim was to examine the relation of forced expiratory volume (FEV₁), forced vital capacity (FVC), and the ratio of FEV₁ to FVC with SCD in a population-based sample of men.

Methods. This study was based on 1250 men 42–60 years of age without chronic obstructive pulmonary disease, asthma, and lung cancer. During the 20-year follow-up, 95 SCDs occurred. FEV₁, FVC, and ratio of FEV₁ to FVC were used as lung function tests.

Results. As a continuous variable, each 10% increase in the percentage predicted FEV₁ was associated with 18% (adjusted risk 0.82, 95% CI 0.73–0.93, P < 0.002) reduced risk for SCD. Subjects with most reduced (lowest quintile) FEV₁ had a 3.5-fold increased risk for SCD (95% CI 1.42–8.41, P = 0.006), after adjustment for conventional risk factors. Similar results were observed with FVC. The results remained statistically significant among non-smokers and smokers respectively.

Conclusion. Our study shows that reduced lung function is a robust predictor of SCD in middle-aged men. Lung function test may be useful in risk stratification for SCD in general population.     

70例心脏性猝死患者的临床尸检病理分析

目的探讨心脏性猝死(SCD)的临床特点、病理基础及致死因素,从而为防治SCD提出有效措施。方法回顾性分析我院70例SCD的临床尸检病理资料。结果70例SCD患者中,冠心病猝死43例,主动脉夹层动脉瘤破裂者13例,心肌炎6例,心肌病3例,肺栓塞5例。冠心病猝死43例中,陈旧性心肌梗死(OMI)7例,OMI 急性心肌梗死(AMI)27例,单纯AMI7例。尸检发现冠状动脉粥样硬化Ⅳ级狭窄者33例,其中多支病变者36例。结论SCD病程短骤、凶险,以老年男性多见,冠心病占首位。冠状动脉多支重度粥样硬化性狭窄是重要的病理基础。尽早防治冠心病、高血压,改善心肌供血是预防SCD的根本措施。     

Pathology of sudden cardiac death

Sudden unexpected cardiac death generally occurs in persons with previously unrecognized heart disease. It has become evident that it occurs often enough in patients without any identifiable structural abnormality. Although mechanical cardiac function may seem normal, such patients might have certain discrete anatomic abnormalities, such as myocarditis, focal myocardial fibrosis, hypertrophy of Purkinje-like myocytes, and myocardial disarray. The pathophysiology in patients with acute myocardial infarction (atherothrombosis of the coronary arteries) was discussed.     

Mechanisms of sudden cardiac death

Despite recent advances in preventing sudden cardiac death (SCD) due to cardiac arrhythmia, its incidence in the population at large has remained unacceptably high. Better understanding of the interaction among various functional, structural, and genetic factors underlying the susceptibility to, and initiation of, fatal arrhythmias is a major goal and will provide new tools for the prediction, prevention, and therapy of SCD. Here, we review the role of aberrant intracellular Ca handling, ionic imbalances associated with acute myocardial ischemia, neurohumoral changes, and genetic predisposition in the pathogenesis of SCD due to cardiac arrhythmia. Therapeutic measures to prevent SCD are also discussed.     

心脏猝死的危险分层问题

心脏猝死（sudden cardiac death）是常见的死亡方式之一,也是最具悲剧性质的死亡形式。多年来，人们一直希望能通过危险分层来找出心脏猝死的高危患者，制定预防策略，进而避免或明显减少心脏猝死患者。然而，由于种种原因，这些努力至今仍收效甚微。