Epidemiology of sudden coronary death: population at risk

Sudden coronary death is a major manifestation of clinical coronary artery disease which doubles in incidence with each decade of life after age 45, with women lagging behind men in incidence by 20 years. Some 14% of heart attacks present as sudden death, and 41% of deaths from coronary disease are sudden deaths. Half of all sudden coronary deaths occur in persons without prior overt coronary artery disease. Persons with established coronary disease are at a three- to fourfold increased risk of sudden death, but the proportion of coronary deaths due to sudden death is no higher. This report examines how sudden death evolves over the long term in the general population and in persons with overt coronary artery disease, and attempts to delineate prime candidates and modifiable predisposing factors using the Framingham Heart Study. In asymptomatic persons the risk of sudden death varies over a wide range in relation to risk factors such as systolic blood pressure, serum cholesterol, cigarette smoking, heart rate, electrocardiographic abnormality and relative weight. Multivariate combination of these risk factors identifies 38.6% of sudden deaths in men and 43.8% of sudden deaths in women in the upper quintile of multivariate risk, which are, respectively, 6.0 and 5.8 times greater than the proportion of sudden deaths in the lowest quintile. When overt coronary artery disease is manifest, the major risk factors have less influence on sudden death risk, which becomes determined chiefly by indicators of intrinsic myocardial damage. With cardiac failure there is an eightfold increased risk of sudden death in men, and cardiac failure without concomitant coronary artery disease imposes a 2.7-fold increased risk.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fighting against sudden death: A single or multidisciplinary approach

There are many causes of sudden death ranging from accidents and suicide to vascular events and arrhythmias. Most sudden deaths will occur in people who have not been diagnosed with a serious heart condition but at a very low annual rate. Many of these events are probably vascular and might be prevented by reducing the risk of developing coronary disease. Only a minority of sudden deaths occur in people with established cardiac disease, but in patients with major structural heart disease, the annual rate is high. The causes of sudden death are many in this clinical setting also, but dominated by ventricular arrhythmias and vascular events. There is good evidence that conventional treatments for heart failure, including ACE inhibitors, beta-blockers, aldosterone antagonists and cardiac resynchronisation devices reduce the risk of sudden death. Evidence that statins, aspirin or revascularisation are safe or effective in patients with heart failure is currently lacking. Implantable defibrillators confer a small but definite additional survival advantage by treating arrhythmias that have not been prevented.     

Cardiac failure and sudden death in the Framingham Study

Mortality is examined in patients with cardiac failure in the Framingham study of 5209 subjects. During 30 years of follow-up, the incidence of cardiac failure doubled with each decade of age with a male predominance produced by higher rates of coronary heart disease. Most cardiac failure was associated with hypertension or coronary heart disease. Among 232 men and 229 women in whom cardiac failure developed, sudden death occurred at nine times the general age-adjusted population rate. Cardiac failure alone increased the risk of sudden death fivefold. In those who also had coronary heart disease there was a further doubling of risk. The major predisposing factors for cardiac failure included hypertension, obesity, glucose intolerance, heavy smoking, cardiac enlargement, ECG abnormality, and atrial fibrillation. These were also risk factors for sudden death. These shared modifiable risk factors and cardiac impairments did not entirely account for the markedly increased risk of sudden death in cardiac failure. This suggest that either the damaged myocardium or treatment needed to control the cardiac failure may be at fault.     

Can the mode of death be predicted in patients with angiographically documented coronary artery disease?

To determine whether sudden versus non-sudden cardiac death could be predicted in high risk patients, 1157 medical patients were followed for an average of 46 months after a diagnostic coronary angiogram and 18 clinical, hemodynamic, and angiographic variables known to be associated with a high risk of mortality were analyzed. The total group of 141 deaths was classified into 3 subgroups: (1) 82 sudden deaths (less than 1 hour after onset of symptoms); (2) 46 deaths due to acute myocardial infarction with or without heart failure, and (3) 13 deaths unrelated to cardiac symptoms. In a subset of 64 patients, the duration of electrical systole (QTc) was calculated before angiography and before death. A comparison was made of QTc measurements at entry with QTc values of subjects with normal coronary arteries and normal left ventricular function. Deaths from cardiac causes could often be predicted from older age, male sex, history of myocardial infarction, unstable angina, congestive heart failure, abnormal cardiothoracic ratio, multivessel disease, abnormal left ventricular contraction, and abnormal ejection fraction. However, these variables did not discriminate between sudden and nonsudden cardiac deaths and both modes of death were characterized by depressed left ventricular function and multivessel coronary disease. During follow-up the incidence of acute myocardial infarction was not different in patients with cardiac and noncardiac deaths and in long-term survivors. However, patients dying from cardiac causes had a higher incidence of heart failure. Patients dying suddenly did not present new infarctions during follow-up whereas patients dying from acute myocardial infarction had a 13% incidence of prior infarction and a higher incidence of heart failure. In addition, QTc at entry was longer in nonsurvivors than in normal subjects (p less than 0.0001) and patients experiencing sudden death exhibited the highest incidence of QTc prolongation (greater than or equal to 440 ms) during follow-up (p less than 0.05). We conclude that: (1) although the severity of coronary disease and left ventricular dysfunction are closely related to cardiac mortality, they do not discriminate between sudden and nonsudden cardiac deaths; (2) patients experiencing sudden death are characterized by a low incidence of new myocardial infarction or congestive heart failure and prolongation of the QTc interval during follow-up.     

Sudden cardiac death: can individual risk be predicted?]

Only 30-40% of all victims of sudden cardiac death could so far be classified as risk patients during their lifetime. Risk factors for sudden death have little predictive value in an asymptomatic population: for example, the typical risk profile for the presence of coronary heart disease and changes in the surface-ECG at rest and especially in the surface-ECG under stress. Usually, the victims of sudden cardiac death among top performance athletes have been suffering from a heart disease of which they knew nothing beforehand: below 40 years of age, mostly from hypertrophic cardiomyopathy; beyond 40, predominantly from coronary heart disease. Among the heart diseases, sudden cardiac death is the cause of death most often in hypertrophic cardiomyopathy, in dilatative cardiomyopathy and in certain types of coronary heart disease. Notwithstanding the employment of fully update cardiological diagnostics the risk patients cannot be identified with reliable precision among those suffering from these diseases. It is only clinically manifest persistent ventricular tachycardia or successful reanimation in case of ventricular fibrillation that will definitely pinpoint the patient as being at risk of sudden cardiac death also in the future.     

Exercise and acute cardiovascular events placing the risks into perspective: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism and the Council on Clinical Cardiology

Habitual physical activity reduces coronary heart disease events, but vigorous activity can also acutely and transiently increase the risk of sudden cardiac death and acute myocardial infarction in susceptible persons. This scientific statement discusses the potential cardiovascular complications of exercise, their pathological substrate, and their incidence and suggests strategies to reduce these complications. Exercise-associated acute cardiac events generally occur in individuals with structural cardiac disease. Hereditary or congenital cardiovascular abnormalities are predominantly responsible for cardiac events among young individuals, whereas atherosclerotic disease is primarily responsible for these events in adults. The absolute rate of exercise-related sudden cardiac death varies with the prevalence of disease in the study population. The incidence of both acute myocardial infarction and sudden death is greatest in the habitually least physically active individuals. No strategies have been adequately studied to evaluate their ability to reduce exercise-related acute cardiovascular events. Maintaining physical fitness through regular physical activity may help to reduce events because a disproportionate number of events occur in least physically active subjects performing unaccustomed physical activity. Other strategies, such as screening patients before participation in exercise, excluding high-risk patients from certain activities, promptly evaluating possible prodromal symptoms, training fitness personnel for emergencies, and encouraging patients to avoid high-risk activities, appear prudent but have not been systematically evaluated.     

Risk Factors for Sudden and Non-Sudden Coronary Death

ABSTRACT The impact of risk factors for sudden and non-sudden coronary death was investigated in 3589 Finnish men aged 40–59 years at entry from a prospective population survey. During a mean follow-up time of 11 years, 234 coronary deaths occurred, 150 of which were sudden, i.e. ensuing within 1 hour of the onset of symptoms. The severity of the manifestations of CHD at baseline investigation appeared to be a powerful predictor of sudden coronary death. Smoking and high serum cholesterol were significant predictors of sudden coronary death. High serum cholesterol was an equally significant predictor of sudden and non-sudden coronary death. High blood pressure did not appear to significantly increase sudden coronary death but increased the incidence of non-sudden death significantly. Obesity and diabetes did not appear to be independent risk factors for sudden coronary death. Smoking and high serum cholesterol were significant risk factors for sudden coronary death in men with manifestations of coronary heart disease. The results suggest that reduction of primary risk factors, especially smoking and high serum cholesterol, is important even after coronary heart disease has become manifest.     

Sudden death--epidemiological aspects

Coronary heart disease presents in a disturbingly high percentage of instances as sudden death. A large percentage of cases occur outside the hospital, outside the reach of emergency care. Data on the frequency of sudden death, within the framework of coronary heart disease incidence, are presented. The risk factors for sudden death, as far as it is known, are similar in kind and predictive power to those for myocardial infarction with survival. While there is a great need for new tests which predict susceptibility to sudden death with adequate sensitivity and specificity, the lesson to be learned from all the knowledge already gained is that prevention of premature coronary heart disease as a whole, through appropriate changes in life style, will correspondingly reduce the risk of sudden death in the population as well. This knowledge must be put into action and should have an appreciable effect on the frequency of sudden death while more research on the mechanisms of the condition is being conducted.     

Sudden cardiac death: epidemiology, mechanisms, and therapy

Sudden cardiac death is a major public health problem affecting 500,000 patients annually in the United States alone. The major risk factor for sudden cardiac death is the presence of coronary artery disease, usually in the setting of reduced ejection fraction. Globally, the incidence is expected to rise sharply as the prevalence of coronary artery disease and heart failure continue to increase. However, sudden cardiac death is a heterogeneous condition and may be caused by acute ischemia, structural defects, myocardial scar, and/or genetic mutations. Sudden death may occur even in a grossly normal heart. Beta-blockers can reduce the risk of sudden cardiac death, while implantable cardioverter defibrillators are effective at terminating malignant arrhythmias. Ejection fraction remains the major criterion to stratify patients for defibrillator implantation but this strategy alone is insensitive and nonspecific. Novel clinical, electrophysiologic, and genetic markers have been identified that may increase precision in patient selection for primary prevention therapy. This review discusses the epidemiology, mechanisms, etiologies, therapies, treatment guidelines, and future directions in the management of sudden cardiac death.     

ICD implantation in patients with ischemic left ventricular dysfunction

Opinion statement  Sudden cardiac death (SCD) is responsible for most deaths related to heart disease. Risk stratification in patients with ischemic heart disease can identify patients at increased risk of sudden death who may derive a mortality benefit from an implantable defibrillator. The most commonly used clinical variable for risk stratification and selection of patients for implantable cardioverter-defibrillator (ICD) therapy for primary prevention of sudden death is left ventricular ejection fraction. Because many sudden deaths occur in patients without common high-risk variables and many patients with ICDs do not receive device therapy, further investigation is warranted to improve risk stratification and patient selection for defibrillator therapy.     

A comparison of death certificate out-of-hospital coronary heart disease death with physician-adjudicated sudden cardiac death

The number of deaths due to out-of-hospital coronary heart disease as determined by death certificates was compared with the number physician-adjudicated sudden cardiac deaths in the Framingham Heart Study from 1950 to 1999. Out-of-hospital coronary heart disease deaths overestimated sudden cardiac death by 47%, suggesting that out-of-hospital coronary heart disease death rates derived from death certificates should be interpreted with caution.     

Ischaemic heart disease and prodromes of sudden cardiac death. Is it possible to identify high risk groups for sudden cardiac death?

A study was carried out to determine the incidence of sudden cardiac death in a well defined population in relation to prodromes, medical history, and previous medical consultations before sudden cardiac death. In Frederiksborg county, Denmark (population 332 000), of 1309 consecutive deaths in a six month period, 166 were due to sudden cardiac death; among men aged 50-69, 22% of all deaths were due to sudden cardiac death. The incidence per 1000 population per year by age group (less than 50, 50-69, greater than or equal to 70 years) was 0.19, 3.6, 11.4 in men and 0.12, 1.0, and 6.4 in women. The increasing incidence with age was significant. Ischaemic heart disease or hypertension had been recorded in 75% (124/166) of patients. Prodromes were reported in 54% (38/71) of patients with angina, and in 26% (25/95) without. Nineteen per cent (32/166) had neither prodromes nor overt heart disease. Forty six per cent of patients with known ischaemic heart disease and 24% without had consulted a doctor less than four weeks before death. Eight per cent had had a myocardial infarction within a year of death.     

Ischaemic heart disease and prodromes of sudden cardiac death. Is it possible to identify high risk groups for sudden cardiac death?

A study was carried out to determine the incidence of sudden cardiac death in a well defined population in relation to prodromes, medical history, and previous medical consultations before sudden cardiac death. In Frederiksborg county, Denmark (population 332 000), of 1309 consecutive deaths in a six month period, 166 were due to sudden cardiac death; among men aged 50-69, 22% of all deaths were due to sudden cardiac death. The incidence per 1000 population per year by age group (less than 50, 50-69, greater than or equal to 70 years) was 0.19, 3.6, 11.4 in men and 0.12, 1.0, and 6.4 in women. The increasing incidence with age was significant. Ischaemic heart disease or hypertension had been recorded in 75% (124/166) of patients. Prodromes were reported in 54% (38/71) of patients with angina, and in 26% (25/95) without. Nineteen per cent (32/166) had neither prodromes nor overt heart disease. Forty six per cent of patients with known ischaemic heart disease and 24% without had consulted a doctor less than four weeks before death. Eight per cent had had a myocardial infarction within a year of death.     

Cardiac pathology in 2007 consecutive forensic autopsies.

The incidence of various types of cardiovascular disease was evaluated in 2007 consecutive forensic patients. Cardiovascular deaths accounted for 22.8% of the study patients and atherosclerotic coronary heart disease was the most common type of cardiac disease (18%). Among subjects dying of atherosclerotic coronary disease, sudden death was three times more frequent than acute myocardial infarction. Expected cardiac findings included the incidence of severe coronary atherosclerosis (21%), floppy mitral valves (5%), and congenital bicuspid aortic valves (1%). Major cardiac findings occurred in 32% and minor cardiac findings were found in 40%. Only 17% of hearts were anatomically normal. An unexpected cardiac necropsy finding included the high frequency of myocardial bridges (23%). Unexpected cardiac findings included the low incidence of acute myocarditis (0.6%) and common finding of tunneled epicardial coronary arteries ("myocardial bridges") (23%).     

冠心病猝死的相关因素分析

目的探讨冠心病患者心脏性猝死的发生率及其相关因素。方法回顾分析46例冠心病患者住院期间发生心脏性猝死的有关临床资料,男性32例,女性14例,年龄38-83（49．5±10．7）岁。收集患者的诱因、心电图（ECG）、超声心动图、动态心电图、X线胸片、心电监护、电解质等资料,根据患者相关项目逐项进行分析。结果46例猝死患者占同期冠心病总住院数的2．2％。多数发生猝死的冠心病患者存在一定高危因素,电解质紊乱、Lown3-5级室早、高度房室传导阻滞、束支传导阻滞、心脏扩大、左室肥厚、心功能不全、持续心肌缺血等因素均可触发致命性心律失常;猝死起始的ECG类型及其演变过程多有一定规律性。结论冠心病患者的心脏性猝死发生率为2．2％。冠心病患者发生猝死与电解质紊乱、Lown3-5级室早、高度房室传导阻滞、束支传导阻滞、心脏扩大、左室肥厚、心功能不全、持续心肌缺血等高危因素密切相关。有效控制危险因素能大大降低冠心病猝死发生率。     

Clinical trial data on the cardioprotective effects of beta-blockade

In most patients with heart failure the underlying cause is coronary artery disease (CAD). They have a poor prognosis and die slowly from deteriorating cardiac function or suddenly from ventricular fibrillation or atheromatous plaque rupture. Two key aims of treatment, therefore, are to slow the progression of underlying CAD and the resulting heart failure and to reduce the risk of sudden death. The impact of drugs on CAD and sudden death can be assessed most effectively in patients who have recovered from a myocardial infarction (post-MI patients). Beta-blockers have been studied in at least 25 trials in post-MI patients and their capacity to reduce mortality and re-infarction has been well documented. About 50% of those who die in post-MI trials die suddenly and beta-blockers particularly propranolol, timolol and metoprolol have been shown to reduce the risk of sudden death significantly. Further evidence that beta-blockers are cardioprotective in post-MI patients can be obtained from trials of other drugs by noting the mortality rates in those patients who were also on a beta-blocker. In three trials of antiarrhythmic drugs and two trials of ACE inhibitors, those on beta-blockers had a better prognosis. There is therefore good evidence that in a patient population known to have serious CAD, beta-blockers can effectively reduce the risk of major coronary events and are particularly effective in reducing the risk of sudden death.     

Hazards,Risks, and Threats of Heart Disease from the Early Stages to Symptomatic Coronary Heart Disease and Cardiac Failure

The epidemiologic approach to investigation of atherosclerotic cardiovascular disease has provided many insights into the preclinical and clinical spectrum of the disease. The hazard of developing atherosclerotic cardiovascular disease is substantial with coronary heart disease (CHD), the most common and most lethal feature. The outlook in those who manage to survive the initial episode is also serious, with a 10-year mortality rate of 37% for persons with angina and a 55% rate for those sustaining a myocordial infarction (M). Fifteen percent of persons developing CHD present with a fatal event, and 38% of infarctions go unrecognized. The presence of atherosclerosis in one vascular territory imposes an increased risk of its appearing in another area at two to six times the general population rate. The major cardiovascular risk factors adversely affect all arterial vascular territories so that correction of risk factors targeted at one particular atherosclerotic outcome may also favorably influence the other risk factors. Coronary disease is the most prevalent lethal hazard of hypertension, dyslipidemia, glucose intolerance, and cigarette smoking. These risk factors cluster and optimal therapy must improve the whole risk profile. Women share the same risk factors for CHD as men. Although women have a lower absolute risk for most risk factors, a high total/HDL cholesterol ratio, left ventricular hypertrophy, and diabetes each tend to eliminate the female advantage. Menopause also promptly escalates risk threefold. Although women tend to have a lower incidence than men, the initial attack is just as highly lethal in women, and their subsequent outlook as survivors is at least as serious as for men. Sudden death is a pre-eminent feature of coronary disease and cardiac failure. Coronary disease increases sudden death risk 3.3-fold and cardiac failure 4.8-fold. Sudden death incidence varies in relation to the same cardiovascular risk factors as coronary heart disease, with no unique risk factors identified. However, multivariate combinations of these in a profile can identify high-risk candidates for sudden death as well as coronary attacks in general. The key to prevention of sudden death is to prevent coronary attacks and cardiac failure.Despite aggressive cardiac revascularization and treatment of hypertension, congestive heart failure (CHF) has not decreased in prevalence, and innovations in the treatments of overt failure have not substantially improved survival. Median survival is only 1.7 years for men and 3.2 years for women. The conditional probability of developing CHF can be estimated using a logistic function comprised of age, systolic pressure, vital capacity, heart rate, ECG-left ventricular hypertrophy (LVH), glucose intolerance, x-ray enlargement, and presence of CHD and heart murmurs. Eight percent of CHF events occur in persons in the upper quintile of multivariate risk. Continued clinical, metabolic, and epidemiologic research have expanded and refined atherosclerosis risk factors. The lipid connection is now concerned with the apoprotein makeup of the lipids, subfractions of lipids, and Lp(a). The diabetic influence is now focused on insulin resistance. Ambulatory monitoring is being used to evaluate blood pressure and silent ischemia. Fibrinogen and leukocyte counts have emerged as possible indicators of unstable lesions.Prospects for primary and secondary prevention are good if public health measures, health education, and preventive medicine are implemented based on existing knowledge of correctable or avoidable risk factors. The potential for more effective prevention continues to expand, and great advances have already been made in countries where aggressive preventive measures have been implemented to correct the major established risk factors.     

Sudden death secondary to cardiac arrhythmias: mechanisms and treatment strategies

PURPOSE OF REVIEW: This article reviews mechanisms and available therapeutic options for arrhythmias leading to sudden cardiac death in patients with coronary artery disease. RECENT FINDINGS: Intensive efforts have led to a better understanding of the pathophysiology and various treatments of sudden cardiac death. Antiarrhythmic medications have not demonstrated a survival benefit. Beta-adrenergic blocking agents have been revalidated in recent studies to improve survival and reduce risk of sudden cardiac death in patients with myocardial infarction. Angiotensin-converting enzyme inhibitors and aldosterone antagonists should also be used in these patients. Data from randomized trials demonstrate significant survival benefit with an implantable cardioverter-defibrillator and indications have expanded. Patients with established ischemic cardiomyopathy do not require electrophysiologic studies for induction of tachyarrhythmias based on these trials. One recent trial did not demonstrate mortality reduction with implantable defibrillators in patients with recent myocardial infarction. Devices may not provide survival benefit in patients with advanced New York Heart Association class IV heart failure. SUMMARY: The incidence of arrhythmia-related sudden death in the general population remains relatively high. Better risk stratification tools are needed to identify high-risk patients in the general population and in those with known coronary disease and to exclude low-risk patients.     

How to evaluate sudden cardiac death risk after myocardial infarction?

Sudden cardiac death is the mode of death of more than half of coronary heart disease patients. Preventing sudden cardiac death involves prevention of ventricular arrhythmias occurrence as well as the treatment by an implantable cardioverter defibrillator. The evaluation of sudden cardiac death risk should consider the underlying cardiopathy, the associated coronary risk factors and all pharmacological treatment efficient to reduce ventricular remodeling and myocardial ischemia. Only significant low ejection fraction and positive ventricular testing in some cases are now considered are now considered by the current French recommendations for cardioverter defibrillator implantation in primary prevention. However, other noninvasive markers such as heart rate variability and T wave alternans are of interest in sudden cardiac death risk stratification after myocardial infarction.     

Kidney dysfunction and sudden cardiac death among women with coronary heart disease

We evaluated the association between kidney dysfunction and sudden cardiac death risk among ambulatory women with coronary heart disease. The Heart and Estrogen Replacement Study evaluated the effects of hormone treatment on cardiovascular events among 2763 postmenopausal women with coronary heart disease. Kidney dysfunction was categorized by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease equation. Multivariate proportional hazards models were used to adjust for cardiovascular risk factors, congestive heart failure, and myocardial infarction. At baseline, 37% (n=1027) had an eGFR of >60 mL/min, 54% (n=1503) had an eGFR of 40 to 60 mL/min, and 8% (n=230) had an eGFR of <40 mL/min. During the 6.8-year follow-up period, there were 136 adjudicated sudden cardiac deaths. The rate of sudden cardiac death was higher in those with lower kidney function (0.5% per year among those with an eGFR >60; 0.6% per year with an eGFR between 40 and 60; and 1.7% per year with an eGFR <40 mL/min; P for trend <0.001). After multivariate analysis with baseline risk factors, eGFR at 40 to 60 mL/min was not a significant predictor, but eGFR at <40 mL/min remained strongly associated with sudden cardiac death (hazard ratio: 3.2; 95% CI: 1.9 to 5.3); adjustment for incident congestive heart failure and myocardial infarction during follow-up diminished this association (hazard ratio: 2.3; 95% CI: 1.3 to 3.9), suggesting that congestive heart failure and myocardial infarction mediated only part of the association between kidney dysfunction and sudden cardiac death. Advanced kidney dysfunction is an independent predictor of sudden cardiac death among women with coronary heart disease.