The epidemiology of sudden unexpected death: risk factors for men and women in the Framingham Heart Study

Family history, socioeconomic factors, comorbidities, health behaviors, and the risk of sudden cardiac arrest

Genetic, environment, and behaviour factors have a role in causing sudden cardiac arrest (SCA). We aimed to determine the strength of the association between various risk factors and SCA incidence. We conducted a multicentre case-control study at 17 hospitals in Korea from September 2017 to December 2020. The cases included out-of-hospital cardiac arrest aged 19-79 years with presumed cardiac aetiology. Community-based controls were recruited at a 1:1 ratio after matching for age, sex, and urban residence level. Multivariable conditional logistic regression analysis was conducted. Among the 1016 cases and 1731 controls, 948 cases and 948 controls were analysed. A parental history of SCA, low educational level, own heart disease, current smoking, and non-regular exercise were associated with SCA incidence (Adjusted odds ratio [95% confidence interval]: 2.51 [1.48-4.28] for parental history of SCA, 1.37 [1.38-2.25] for low edication level, 3.77 [2.38-5.90] for non-coronary artery heart disease, 4.47 [2.84-7.03] for coronary artery disease, 1.39 [1.08-1.79] for current smoking, and 4.06 [3.29-5.02] for non-regular exercise). Various risk factors related to genetics, environment, and behaviour were independently associated with the incidence of SCA. Establishing individualised SCA prevention strategies in addition to general prevention strategies is warranted.

Sudden cardiac death in South India: Incidence, risk factors and pathology

BACKGROUND

Sudden cardiac death (SCD) is a major cause of mortality secondary to coronary artery disease (CAD) in the industrialized societies. Although South Asians have a high prevalence of CAD, the frequency and underlying pathology of SCD among this population are unknown.

METHODS

Medical records of consecutive patients presenting with unexplained sudden death (USD) in a tertiary care center were reviewed. Patients with trauma, violent deaths, positive toxicology and non-cardiac pathology were excluded to determine sudden cardiac death (SCD). Cardiac pathological findings were analyzed by autopsy. SCD rate was estimated based on census and government vital statistics for the years studied.

RESULTS

During a two year period, 223 patients (mean age 55 + 10 yrs, 78.9% male, body mass index 26 + 4, 60% smokers, 39% known CAD, 46% hypertension, 43% diabetes) presented to hospital with USD. SCD was attributed to myocardial infarction (MI) in 87% of cases; 69% were acute (96% anterior MI); 76% were small/moderate infarct and 9.9% of the cohort had normal hearts. Based on official municipal vital statistics, the SCD rate in those >35 yrs of age was estimated as 39.7/100,000 with male/female ratio of 4.6.

CONCLUSIONS

SCD in this south Indian city occurred predominantly in men of relatively young age and was most frequently associated with small or moderate-sized acute MI. Improved health care access, preventive measures and enhanced emergency management may reduce SCD from acute MI in this locale.

CAP2 in cardiac conduction, sudden cardiac death and eye development

Sudden cardiac death kills 180,000 to 450,000 Americans annually, predominantly males. A locus that confers a risk for sudden cardiac death, cardiac conduction disease, and a newly described developmental disorder (6p22 syndrome) is located at 6p22. One gene at 6p22 is CAP2, which encodes a cytoskeletal protein that regulates actin dynamics. To determine the role of CAP2 in vivo, we generated knockout (KO) mice. cap2⁻/cap2⁻ males were underrepresented at weaning and ~70% died by 12 weeks of age, but cap2⁻/cap2⁻ females survived at close to the expected levels and lived normal life spans. CAP2 knockouts resembled patients with 6p22 syndrome in that mice were smaller and they developed microphthalmia and cardiac disease. The cardiac disease included cardiac conduction disease (CCD) and, after six months of age, dilated cardiomyopathy (DCM), most noticeably in the males. To address the mechanisms underlying these phenotypes, we used Cre-mediated recombination to knock out CAP2 in cardiomyocytes. We found that the mice developed CCD, leading to sudden cardiac death from complete heart block, but no longer developed DCM or the other phenotypes, including sex bias. These studies establish a direct role for CAP2 and actin dynamics in sudden cardiac death and cardiac conduction disease.

Cardiac aetiology of cardiac arrest: percutaneous coronary interventions during and after cardiopulmonary resuscitation

Management and prevention of cardiac arrest in the setting of heart disease is a challenge for modern cardiology. After reviewing the aetiology of sudden cardiac death and discussing the way to identify candidates at risk, we emphasise the role of percutaneous coronary interventions during and after cardiopulmonary resuscitation in the treatment of patients with return of spontaneous circulation after cardiac arrest.

Pattern of sudden death at Ladoke Akintola University of Technology Teaching Hospital, Osogbo, South West Nigeria

Background

The purpose of this study was to determine the etiology and epidemiologic characteristics of sudden death at Ladoke Akintola University of Technology (LAUTECH) Teaching Hospital, South West Nigeria.

Methods

This was a retrospective descriptive study of all cases of natural unexpected death, either occurring out of hospital or less than 24 hours after admission to LAUTECH Teaching Hospital, over a nine-year period from January 2003 to December 2011. Data were generated from information in the case notes and autopsy reports for these cases.

Results

Sudden death accounted for 29 (4.0%) of 718 adult medical deaths and 1.0% of all adult medical admissions. Out-of-hospital deaths occurred in 72.4% of cases. The mean age of the patients was 46.8 ± 11.5 (range 25–74) years. The male to female ratio was 6.25:1. Cardiovascular disease were the most common cause of death (51.7%), followed by respiratory disease (20.7%), pulmonary thromboembolism (10.4%), central nervous system disease (13.8%), gastrointestinal disorders (13.8%), severe chemical/drug poisoning (13.8%), and combined cardiovascular and central nervous system disease (13.8%). Hypertension-related causes were responsible for 14/29 (48.3%) of the sudden deaths. Hypertensive heart disease accounted for 86.7% of the cardiovascular deaths, hypertensive heart failure accounted for 73.3%, whilst all heart failure cases accounted for 80.0%. Left ventricular hypertrophy was present in 69.2% of the patients with hypertensive heart disease. Moderate to severe atheromatous changes occurred in the aorta in 38.5% of patients aged ≥50 years. No case of myocardial infarction was found.

Conclusion

Hypertensive heart disease and hypertension-related disorders are the most common causes of sudden death in South West Nigeria, so effective public health strategies should be channeled towards prevention, detection, and treatment of hypertension.

Clinical correlates and heritability of QT interval duration in blacks: the Jackson Heart Study

BACKGROUND

Electrocardiographic QT interval prolongation is a risk factor for sudden cardiac death and drug-induced arrhythmia. The clinical correlates and heritability of QT interval duration in blacks have not been well studied despite their higher risk for sudden cardiac death compared with non-Hispanic whites. We sought to investigate potential correlates of the QT interval and estimate its heritability in the Jackson Heart Study.

METHODS AND RESULTS

The Jackson Heart Study comprises a sample of blacks residing in Jackson, Miss, of whom 5302 individuals with data at the baseline examination were available for study. Jackson Heart Study participants on QT-altering medications, with bundle-branch block, paced rhythm, atrial fibrillation/flutter, or other arrhythmias were excluded, resulting in a sample of 4660 individuals eligible for analyses. The relation between QT and potential covariates was tested using multivariable stepwise linear regression. Heritability was estimated using Sequential Oligogenic Linkage Analysis Routine in a subset of 1297 Jackson Heart Study participants in 292 families; the remaining sample included unrelated individuals. In stepwise multivariable linear regression analysis, covariates significantly associated with QT interval duration included R-R interval, sex, QRS duration, age, serum potassium, hypertension, body mass index, coronary heart disease, diuretic use, and Sokolow-Lyon voltage (P < or = 0.01 for all). The heritability of QT interval duration in the age-, sex-, and R-R interval-adjusted model and in the fully adjusted model was 0.41 (SE, 0.07) and 0.40 (SE, 0.07; P < 10(-11) for both), respectively.

CONCLUSIONS

There is substantial heritability of adjusted QT interval in blacks, supporting the need for further investigation to identify its genetic determinants.

Erythrocyte magnesium and prostaglandin dynamics in chronic sleep deprivation

BACKGROUND AND HYPOTHESIS

The mechanism of sudden cardiac death occurring in patients with chronic fatigue is controversial. This study was designed to define a hypothesis that coronary arterial spasm and thrombus formation can occur during chronic fatigue.

METHODS

For evaluating the feasibility of coronary arterial spasm, erythrocyte magnesium (Mg) was measured. Blood coagulability was evaluated by the change of prostaglandin concentration. Subjects included 16 healthy male volunteers (mean age 21.6 +/- 2.5 years). Test conditions were as follows: (A) control state: a day following a night of good sleep; (B) temporary sleep deprivation: a day preceded by < 3 h of sleep; (C) chronic sleep deprivation: a day preceded by a month during which sleep lasted < 60% of that in condition (A) above. The erythrocyte Mg concentration was measured by the atomic absorption method. The plasma concentration of thromboxane B2 and 6-keto-prostaglandin F1 alpha were measured in eight subjects by radioimmunoassay method.

RESULTS

(1) Mean erythrocyte Mg concentration was significantly less in chronic sleep deprivation (1.1 +/- 0.4 mg/dl) than in the control state (1.8 +/- 0.4 mg/dl, p < 0.01) or in temporary sleep deprivation (1.6 +/- 0.4, p < 0.01). (2) The level of thromboxane B2 was significantly higher during chronic sleep deprivation than under control conditions (104.4 +/- 78.0 vs. 20.4 +/- 9.0 pg/ml, p < 0.05). (3) There were no significant intergroup differences in 6-keto-prostaglandin F1 alpha level.

CONCLUSION

These findings could support the hypothesis that coronary arterial spasm and thrombus formation occur in chronic sleep deprivation.

Genetic determinants of QT interval variation and sudden cardiac death

Electrocardiographic QT interval prolongation or shortening is a risk factor for sudden cardiac death. The study of Mendelian syndromes in families with extreme long and short QT interval duration and ventricular arrhythmias has led to the identification of genes encoding ion channel proteins important in myocardial repolarization. Rare mutations in such ion channel genes do not individually contribute substantially to the population burden of ventricular arrhythmias and sudden cardiac death. Only now are studies systematically testing the relationship between common variants in these genes--or elsewhere in the genome--and QT interval variation and sudden cardiac death. Identification of genetic variation underlying myocardial repolarization could have important implications for the prevention of both sporadic and drug-induced arrhythmias.

Possible association of the human KCNE1 (minK) gene and QT interval in healthy subjects: evidence from association and linkage analyses in Israeli families

QT interval prolongation is associated with increased risk of sudden and non-sudden cardiac death. Potassium channel gene variants are associated with inherited long QT syndromes. Using linkage and association analyses, we investigated whether variants in the potassium channel subunit KCNE1 are associated with QTc intervals in an unselected population sample of 80 kindreds living in kibbutz settlements in Israel. Variance-component linkage analysis revealed weak evidence of linkage of KCNE1 polymorphisms with QTc intervals. Family-based association analysis showed a significant association between the G38S polymorphism and QTc interval. Further quantitative trait association analysis demonstrated a significant residual heritability component (h(2)= 0.33), and that the effect of the G38S variant allele is modified by gender. Estimated maximum likelihood parameters from these models indicated that male gender, age, hypertension, diabetes, hypercholesterolemia, fibrinogen and BMI were positively associated with QTc interval; level of education and cigarette smoking showed an inverse association. Both erythrocyte membrane n-6 and n-3 fatty acids showed a significant inverse association with QTc interval. While more than 15.8% of QTc variability was contributed by covariates, another 4.7% was explained by dietary factors, the G38S polymorphism explained 2.2%, and approximately 36% was explained by polygenes. An in silico analysis showed also that the novel V80 SNP, another KCNE1 synonymous variant, abolishes the recognition for a splicing enhancer, which may lead to an increased effect of the G38S mutation. These results demonstrate that, in addition to polygenic background, dietary factors and other covariables, the KCNE1 G38S variant is involved in determining QTc levels in this population-based sample of families.

Sex differences in outcome after ventricular fibrillation in out-of-hospital cardiac arrest

INTRODUCTION

Previous studies have shown that early defibrillation programs improve survival after an out-of-hospital cardiac arrest (OHCA). Reports also suggest that women fare worse than men do after cardiovascular events, but there is no population-based study of sex differences after an OHCA with early defibrillation. We, therefore, compared the short- and long-term survival and quality-of-life (QOL) in women and men after an OHCA.

METHODS

All patients with a ventricular fibrillation (VF) OHCA who received early defibrillation in Olmstead County, Minnesota between November 1990 and December 2000 were included. Using medical records and the cardiac arrest database, the short- and long-term survival and QOL based on a SF-36 survey of each sex were compared. Adjusted QOL scores were obtained by using age- and sex-specific norms from a sample of the general U.S. population; an adjusted score of 50 (normalized mean) was considered normal.

RESULTS

Thirty-seven female and 163 male patients presented with a VF OHCA and early defibrillation. Survival to hospital admission was significantly better for women than men [30 female survivors to admission (81%), 112 male (69%), p = 0.04]. Paradoxically, survival to discharge among those admitted was worse for women [13 female survivors to discharge (43%), 66 male (61%), p = 0.04]. The average length of follow-up was 4.8+/-3.0 years. The 5-year expected survival was 83% in women and 78% in men (p = 0.48). There was no difference in call-to-shock time (6+/-2, 6+/-2 min, p = 0.6) or whether the arrest was witnessed (86, 82%, p = 0.64). There was no statistical difference between women and men in age (64+/-17, 65+/-14 years), ejection fraction (40+/-17, 40+/-18%), diabetes (17, 29%, p = 0.16), hypertension (23, 28%, p = 0.58) or known CAD (27, 48%, p = 0.06). Adjusted QOL scores were similar between women and men in terms of pain (52+/-9, 52+/-10) vitality (47+/-11, 40+/-9), general health (49+/-9, 44+/-7), social function (51+/-10, 51+/-8), and mental health (50+/-10, 49+/-6).

CONCLUSION

Women are more likely to survive to hospital admission following an OHCA. However, admitted women less likely to survive their hospital stay. Long-term survival and QOL are equally favorable in both sexes.

Gender differences in electrophysiologic effects of mental stress and autonomic tone inhibition: a study in health individuals

INTRODUCTION

Gender differences exist in electrophysiologic properties and the occurrence of certain arrhythmias. Mental stress may trigger serious arrhythmias, including ventricular tachycardias and ventricular fibrillation. This study investigates gender differences in the electrophysiologic effects on different levels of the cardiac conduction system elicited by mental stress and autonomic tone inhibition.

METHODS AND RESULTS

Twenty-three healthy volunteers (11 male and 12 female) participated in the study. Electrophysiologic and hemodynamic variables were measured at baseline, during mental stress produced by Stroop's color word conflict test (CWT), and after autonomic tone inhibition (ATI) with propranolol (0.15 mg/kg) and atropine (0.02 mg/kg). During CWT, men showed shorter QT and JT durations, whereas women had shorter refractoriness in the atrial tissue and AV node. After ATI, no gender differences in sinus nodal properties were noted, whereas AV nodal refractoriness and conduction time became shorter in women, and QT and JT duration and the refractory period of the right ventricle were shorter in men.

CONCLUSION

In women, mental stress produces a pronounced effect on the AV node and on the sinus node. Men react with a more pronounced effect on ventricular electrophysiologic properties. Certain gender differences in cardiac electrophysiologic properties seem to be intrinsic. After ATI, women have a higher heart rate and shorter AV nodal refractoriness but longer QT and JT intervals and longer effective refractory periods in the right ventricle. These differences may partly explain why certain arrhythmias occur more often in women than in men.

The Association Between Cholesterol and Mortality in Heart Failure Comparison Between Patients With and Without Coronary Artery Disease

Hypercholesterolemia is a risk factor for development of coronary artery disease (CAD), however, several reports have suggested that low serum cholesterol is associated with a worse prognosis in patients with congestive heart failure (CHF). The objective of this study was to determine the prognostic value of cholesterol for CHF. The study subjects consisted of 133 consecutive patients hospitalized in our institution for progressive heart failure from April 2000 to March 2003. Thirty-two percent of the patients had CAD. After improvement of congestive heart failure and discharge from the hospital, lipid profiles, including serum total cholesterol (TC), triglycerides, and high and low density lipoprotein cholesterol (HDL, LDL, respectively), were obtained. During the follow-up period (2.3 +/- 0.9 years), 21 patients died. There was a significant difference between survivors and nonsurvivors in HDL (53 +/- 15, 43 +/- 15 mg/dL, P = 0.01), but no differences were observed in other variables. In patients with CAD, survivors had significantly lower TC concentrations (179 +/- 30 versus 246 +/- 55 mg/dL, P = 0.004), although in patients without CAD, survivors had significantly higher TC concentrations (203 +/- 37 versus 170 +/- 40 mg/dL, P = 0.02). Multivariate analysis showed high TC predicted a worse outcome in patients with CAD (odds ratio (OR) = 1.052, 95% confidence interval (CI) 1.002-1.104, P = 0.04), but a better outcome in patients without CAD (OR = 0.972, 95% CI 0.948-0.997, P = 0.03), independent of age, gender, medication, and complications. Thus, low serum cholesterol is associated with an improved outcome in patients with CAD, while it predicts a worse outcome in patients without CAD.

Effects of chronic sleep deprivation on autonomic activity by examining heart rate variability, plasma catecholamine, and intracellular magnesium levels

Chronic sleep deprivation is associated with cardiovascular events. In addition, autonomic activity determined from the levels of the heart rate variability (HRV), plasma catecholamine, and intracellular magnesium (Mg) are important in the pathophysiology of cardiovascular events. This study therefore aimed to determine the effects of chronic sleep deprivation on autonomic activity by examining the HRV, plasma catecholamine, and intracellular magnesium levels. Thirty (30) healthy male college students ranging in age from 20 to 24 years of age (average 22 +/- 1 years; mean +/- SD) with no coronary risk factors such as hypertension, diabetes mellitus, hyperlipidemia or a family history of premature coronary artery disease (CAD) were included in the study. Over a 4-week period, the volunteers' plasma levels of epinephrine, norepinephrine, and erythrocyte-Mg were measured. The study was made during the 4 weeks before and immediately after college finals exams. HRV, obtained from 24-hour ambulatory ECG monitoring, included time and frequency domain indices. The HRV indices and erythrocyte-Mg decreased while norepinephrine increased during chronic sleep deprivation. It is concluded that chronic sleep deprivation causes an autonomic imbalance and decreases intracellular Mg, which could be associated with chronic sleep deprivation-induced cardiovascular events.

Effect of chronic stress and sleep deprivation on both flow-mediated dilation in the brachial artery and the intracellular magnesium level in humans

BACKGROUND

Chronic mental and physical stress has been suggested to be a trigger for cardiovascular events. In addition, a reduction in levels of intracellular magnesium has been reported to cause vasoconstriction while enhancing platelet-dependent thrombosis.

HYPOTHESIS

The purpose of this study was to investigate whether chronic stress affects endothelial function and intracellular magnesium levels in humans.

METHODS

Flow-mediated dilation (endothelium-dependent vasodilation) and sublingual nitroglycerin-induced dilation (0.3 mg, endothelium-independent vasodilation) were measured in the brachial artery in 30 healthy male college students, aged 22 +/- 1 years, using high-resolution ultrasound both before and immediately after a 4-week final term examination period. Erythrocyte magnesium concentration was measured simultaneously. All students had chronic sleep deprivation for 4 weeks, during which sleep lasted < 80% of that on ordinary days; in addition, the students were under great stress to pass the examination. This condition was considered to be chronic stress.

RESULTS

Chronic stress decreased flow-mediated dilation and erythrocyte magnesium concentration (from 7.4 +/- 3.0 to 3.7 +/- 2.3%, p < 0.05; from 5.7 +/- 0.4 to 5.5 +/- 0.4 mg/ml, p < 0.05, respectively). The change in flow-mediated dilation correlated significantly with that of the erythrocyte magnesium concentration (r = 0.43, p < 0.05), but not with nitroglycerin-induced dilation.

CONCLUSIONS

Chronic stress was found to attenuate endothelial function, which may also be associated with a reduction in the intracellular magnesium level in humans.

The epidemiology of out-of-hospital 'sudden' cardiac arrest

It is difficult to assemble data from an out-of-hospital cardiac arrest since there is often lack of objective information. The true incidence of sudden cardiac death out-of-hospital is not known since far from all of these patients are attended by emergency medical services. The incidence of out-of-hospital cardiac arrest increases with age and is more common among men. Among patients who die, the probability of having a fatal event outside hospital decreases with age; i. e. younger patients tend to more often die unexpectedly and outside hospital. Among the different initial arrhythmias, ventricular fibrillation is the most common among patients with cardiac aetiology. The true distribution of initial arrhythmias is not known since several minutes most often elapse between collapse and rhythm assessment. Most patients with out-of-hospital cardiac arrest have a cardiac aetiology. Out-of-hospital cardiac arrests most frequently occur in the patient's home, but the prognosis is shown to be better when they occur in a public place. Witnessed arrest, ventricular fibrillation as initial arrhythmia and cardiopulmonary resuscitation are important predictors for immediate survival. In the long-term perspective, cardiac arrest in connection with acute myocardial infarction, high left ventricular ejection fraction, moderate age, absence of other heart failure signs and no history of myocardial infarction promotes better prognosis. Still there is much to learn about time trends, the influence of patient characteristics, comorbidity and hospital treatment among patients with prehospital cardiac arrest.

Urinary antispasmodic use and the risks of ventricular arrhythmia and sudden death in older patients

OBJECTIVES

The introduction of new medications to treat overactive bladder has resulted in a significant increase in the number of individuals with this condition who use medications for symptoms. Formal epidemiological studies of the safety of these medications in typical patient populations are lacking, particularly studies of serious events. We sought to determine whether the use of urinary antispasmodics increases the risk of ventricular arrhythmias or sudden death.

DESIGN

Retrospective cohort study.

SETTING

Retrospective analysis of data of participants in community, hospital or nursing home setting.

PARTICIPANTS

Fourteen thousand six hundred thirty-eight subjects with a diagnosis of urinary incontinence made between January 1, 1991, and June 30, 1995; all were aged 65 and older and enrolled in Medicare and Medicaid or the Pharmacy Assistance for the Aged and Disabled programs of New Jersey.

MEASUREMENTS

Filled prescriptions for oxybutynin (Ditropan), flavoxate (Urispas), hyoscyamine (Cystospas), and hyoscyamine sulfate (Cystospas-M) were used to define days of exposure to these drugs. We also identified all use of nonsedating antihistamines and cytochrome P450 3A4 inhibitors, and their concurrent use, to serve as a positive control exposure. Two outcomes were then defined: a new diagnosis of ventricular arrhythmia combined with initiation of an antiarrhythmic medication and sudden death. Other covariates, including clinical, demographic, medication use, and healthcare utilization variables, were also assessed. Adjusted risk ratios of ventricular arrhythmia and sudden death were derived from multivariable Cox proportional hazards models.

RESULTS

There was no significant association between periods of use of urinary antispasmodics and the development of ventricular arrhythmias (adjusted risk ratio (RR) = 1.23, 95 confidence interval (CI) = 0.87-1.75) or sudden death (adjusted RR = 0.70, 95% CI = 0.28-1.74). A significantly increased risk of ventricular arrhythmia was observed for the positive control regimen, concurrent use of nonsedating antihistamines and cytochrome P450 3A4 inhibitors (adjusted RR = 5.47; 95% CI = 1.34-22.26), but not for use of either drug group alone. Concurrent use of nonsedating antihistamines and cytochrome P450 3A4 inhibitors was also associated with a significant increase in the risk of sudden death (adjusted RR = 21.50, 95% CI = 5.23-88.37). Other variables significantly associated with ventricular arrhythmia included ischemic heart disease and congestive heart failure, whereas nursing home use before the index date was associated with a decreased likelihood of receiving a diagnosis of and treatment for ventricular arrhythmia. Other variables significantly associated with sudden death included male gender, black race, and congestive heart failure.

CONCLUSIONS

Antimuscarinic urinary antispasmodics available before 1996 were not associated with an increased risk of ventricular arrhythmias and sudden death. Additional study will be required to confirm these results, exclude the possibility of unmeasured confounders contributing to any lack of an observed relationship, and extend these findings to newer agents such as tolterodine.

PAI-I 4G/5G polymorphism and sudden cardiac death in patients with coronary artery disease

The 4G/5G polymorphism of the plasminogen activator inhibitor type I (PAI-I) gene is involved in coronary artery disease (CAD), with the highest risk in 4G/4G homozygotes. The role of PAI-I polymorphism in patients suffering from CAD and history of sudden cardiac death (SCD) has not been addressed yet. We studied the frequency distribution of the PAI-I gene to test the hypothesis that the 4G/4G genotype favors myocardial ischemia and, even in the absence of acute infarction, promotes SCD in patients with CAD.

METHODS

The PAI-I 4G/5G genotypes and PAI-I antigen plasma levels were determined in 97 patients with CAD and a history of SCD treated with an implantable cardioverter defibrillator (ICD) (defibrillator group) comparing to 113 patients with CAD but no history of SCD (control group).

RESULTS

The defibrillator group consisted of significantly more 4G/4G homozygotes and higher PAI-I levels than the control group (44% vs. 24%, 173+/-41 vs. 144+/-49 ng/ml; P<.01). The carriers of 4G allele had a significantly higher risk for SCD (odds ratio (OR) 1.9) with the highest risk in the 4G/4G genotype (OR 3.6, P<.01).

CONCLUSION

These results suggest that the PAI-I 4G/4G genotype is associated with SCD in patients suffering from CAD.

Platelet glycoprotein Ia gene dimorphism alpha2-807 in malignant arrhythmia in coronary artery disease

It has been shown recently that the variable expression of the platelet collagen receptor integrin alpha2beta1 predisposes to thrombotic risk on the one hand and hemorrhagic risk on the other hand. The level of expression of the integrin alpha2beta1 is genetically controlled and associated with the alpha2-807 dimorphism. The expression level of this platelet collagen receptor may play a central role in the rapidly evolving coronary artery lesions that lead to malignant arrhythmia and sudden cardiac death. We studied allelic frequencies of the alpha2-807 dimorphism for their relation as a risk factor for malignant arrhythmia in a well-defined subgroup of patients with coronary artery disease. We compared allelic frequencies (by sequence specific primer polymerase chain reaction) of the dimorphism that is associated with integrin alpha2beta1 levels in 94 Caucasoid survivors of sudden cardiac death with a matched group of 106 patients with coronary artery disease without sudden cardiac death. Gene frequencies in the patient groups did not differ and were similar to those in the general population represented by 217 healthy individuals. There was no overrepresentation of an allele in any group. The inherited dimorphism that is associated with the levels of platelet integrin alpha2beta1 is not associated with malignant arrhythmia in coronary artery disease patients.

Genetic and environmental sources of QT interval variability in Israeli families: the kibbutz settlements family study

QT interval prolongation not attributed to long QT syndromes is reported to be associated with increased risk of sudden and nonsudden cardiac death. Genetic and environmental determinants of QTc interval were investigated in an unselected free living population sample of 80 kindreds residing in kibbutz settlements in Israel. The sample included 214 males and 227 females aged 15-97 years. There was a significant familial aggregation of adjusted QT interval levels, as indicated by inter- and intraclass correlation coefficients significantly different from zero. Complex segregation analysis applied to the sex- and age-adjusted data was not conclusive and heterogeneous etiologies for individual differences were suggested. There was evidence for a single recessive locus (q = 0.173) with a major effect in addition to polygenic effects (h2 = 0.41) that explained the mixture of distributions. In parallel, a nontransmitted environmental major factor in addition to polygenic effects that explained the adjusted variation in QTc could not be rejected. Similar results were obtained upon the adjustment for sex, age, and environmental covariables. The major factor, either genetic or environmental, and polygenic-loci accounted for about 20 and 33% of the adjusted QTc variation, respectively. Furthermore, sex, age, measured environmental covariables, the unmeasured major factor, and the unmeasured polygenes could account for 63% of the variation of QTc in these families. Our data provide evidence for a major factor, either genetic or environmental, in addition to a polygenic background, influencing QT interval levels in a population-based sample of pedigrees.

Predicting sudden death in the population: the Paris Prospective Study I

BACKGROUND

Sudden death was found to share the same set of usual risk factors as coronary events and therefore could not be specifically predicted in the population. It appears, however, that parental history of sudden death has not been investigated yet as a risk factor for sudden death. Therefore, we assessed risk factors, including parental sudden death, associated with the occurrence of sudden death in a long-term cohort study.

METHODS AND RESULTS

We included 7746 men employed by the city of Paris who were 43 to 52 years of age in 1967 to 1972 in the Paris Prospective Study I. Each subject underwent a physical examination and an ECG, provided blood for laboratory tests, and answered questionnaires administered by trained interviewers who paid particular attention to family medical history. Men with known ischemic cardiac disease were further excluded from analysis. For 95.5% of the men, vital status was obtained from specific inquiries until retirement, then by death certificates. Resting heart rate, systolic or diastolic blood pressure, tobacco consumption, body mass index, diabetes status, serum cholesterol, and parental history of sudden death were independent factors associated with sudden death during follow-up (23 years on average). When adjusted for confounding variables, including parental history of myocardial infarction, relative risk of sudden death associated with parental sudden death was 1.80 (95% CI, 1.11 to 2.88).

CONCLUSIONS

Parental sudden death is an independent risk factor for sudden death in middle-aged men. The existence of familial risk factors for sudden death may help provide better identification of subjects at high risk of and early prevention of sudden death.

Sudden unexpected death from cardiac causes in Nigerians: a review of 50 autopsied cases

Fifty cases of sudden and unexpected death from cardiac causes in individuals between the ages of 28 and 80 years are reviewed; the causes and circumstances of the deaths of these individuals are defined. 70% were males and 44% of the deaths occurred in the 41-50 years age group. Death was due to hypertensive heart disease in 82% of the cases and only 18% were previously diagnosed. Acute left ventricular failure was the commonest (68%) cause of death. Only 4% of the total died of acute myocardial infarction from coronary artery disease. The causes of sudden cardiac death in a developing country such as Nigeria, appears to be different to the pattern in Western countries.

Family history as a risk factor for primary cardiac arrest

BACKGROUND

The hypothesis that a family history of myocardial infarction (MI) or primary cardiac arrest (PCA) is an independent risk factor for primary cardiac arrest was examined in a population-based case-control study. In addition, we investigated whether recognized risk factors account for the familial aggregation of these cardiovascular events.

METHODS AND RESULTS

PCA cases, 25 to 74 years old, attended by paramedics during the period 1988 to 1994 and population-based control subjects matched for age and sex were identified from the community by random digit dialing. All subjects were free of recognized clinical heart disease and major comorbidity. A detailed history of MI and PCA in first-degree relatives was collected in interviews with the spouses of case and control subjects by trained interviewers using a standardized questionnaire. For each familial relationship, there was a higher rate of MI or primary cardiac arrest (MI/PCA) in relatives of case compared with relatives of control subjects. Overall, the rate of MI/PCA among first-degree relatives of cardiac arrest patients was almost 50% higher than that in first-degree relatives of control subjects (rate ratio [RR]=1.46; 95% CI=1.23 to 1.72). In a multivariate logistic model, family history of MI/PCA was associated with PCA (RR=1.57; 95% CI=1.27 to 1.95) even after adjustment for other common risk factors.

CONCLUSIONS

Family history of MI or PCA is positively associated with the risk of primary cardiac arrest. This association is mostly independent of familial aggregation of other common risk factors.

Sudden death and physical activity in athletes and nonathletes

Among young athletes, sudden deaths are predominantly associated with cardiomyopathies, coronary artery abnormalities and myocarditis, but coronary heart disease is a reality already in this group. The absolute risk of sudden death is, however, low and the benefits of routine medical screening are small. If an athlete has had any symptoms that arouse suspicion of cardiac disease, the athlete must be meticulously investigated, as an underlying life-threatening illness may be present. Among all nonathletes, as well as athletes > or = 30 years, the predominant cause of sudden death is coronary heart disease. A large number of studies have provided strong evidence suggesting the benefits of physical activity regarding prevention of cardiovascular death and disease. The immediate risk for sudden death is higher during physical activity than during other times, especially among usually sedentary individuals, but inactivity is much more dangerous in the long run. Regular exercise at moderate intensity gives large benefits with small risks. The benefits of irregular and intensive exercise are less clear and the risks higher. For the individual without known heart disease who exercises regularly, the risk for sudden death during physical activity is extremely small.

Incidence and other epidemiological characteristics of sudden cardiac death in northwest Greece

Sudden cardiac death (SCD) has not been investigated separately in Greece. The aim of this study is to describe the epidemiological characteristics of people dying suddenly out of hospital in an area of Greece. In 1990, a population based study was started to detect the cases of people dying suddenly out of hospital (< 1 h after onset of acute symptoms or < 6 h after being seen alive) in a closed population in Northwest Greece (Ioannina area: 160,000 inhabitants). During a 3.5 year period, 283 potential cases aged 30-70 years were identified by monitoring the mortality in the emergency rooms of the two hospitals of the area, the coroner's office and the death certificates from the Government Department of Statistics. The diagnosis of SCD was established in 223 (183 men, 40 women; mean ages 59 and 61 years respectively) after visiting and interviewing the relatives and/or the family doctors within 12 days (range 1-28) after the death. SCD in the study accounts for 50% of all cardiovascular deaths and is the most common cause of death after neoplasia. The most common place of death was home (151 cases, 68%), and in 174 cases (78%) deaths occurred while the patients were relaxing or during routine activities. Prodromal symptoms were reported in 57 cases (26%). The time of day of death showed a circadian variation, with a peak in the late morning from 9:00 to 12:00. Ninety four (42%) had a prior history of heart disease. One hundred and ninety one cases (86%) occurred in the subgroup of age 50-70 years.(ABSTRACT TRUNCATED AT 250 WORDS)

The natural history of borderline isolated systolic hypertension

BACKGROUND

Patients with isolated systolic hypertension are at increased risk for cardiovascular disorders. We attempted to determine whether those with borderline isolated systolic hypertension (defined as a systolic blood pressure of 140 to 159 mm Hg and a diastolic blood pressure below 90 mm Hg) have a greater risk of progression to definite (more severe) hypertension and of major morbid or fatal events than people with normal blood pressure (< 140/90 mm Hg).

METHODS

A total of 2767 of the original participants in the Framingham Heart Study were monitored with biennial examinations for up to 34 years for the development of definite hypertension (defined as a systolic blood pressure of > or = 160 mm Hg, a diastolic blood pressure of > or = 90 mm Hg, or the initiation of antihypertensive therapy) and for major cardiovascular events.

RESULTS

Borderline isolated systolic hypertension was the most common type of untreated hypertension among adults over the age of 60. After 20 years of follow-up, 80 percent of those with borderline isolated systolic hypertension had progression to definite hypertension, as compared with 45 percent of the normotensive participants (P < 0.001). After adjustment for age, sex, and risk factors for cardiovascular disease, participants with borderline isolated systolic hypertension had an excess long-term risk of cardiovascular disease (hazard ratio, 1.47; 95 percent confidence interval, 1.24 to 1.74) and death from cardiovascular disease (hazard ratio, 1.57; 95 percent confidence interval, 1.24 to 2.00), as compared with normotensive participants. In an analysis of pooled data from biennial examinations to study short-term sequelae, subjects with borderline isolated systolic hypertension had an increased risk of progression to definite hypertension (odds ratio, 3.84; 95 percent confidence interval, 3.35 to 4.41) and of cardiovascular disease (odds ratio, 1.39; 95 percent confidence interval, 1.06 to 1.82).

CONCLUSIONS

In both the short term and the long term, subjects with borderline isolated systolic hypertension are at increased risk of progression to definite hypertension and the development of cardiovascular disease.

Resting thallium-201 scintigraphy for identifying viable myocardium in a patient with severe left ventricular dysfunction

Recognizing patients with coronary artery disease in whom severe left ventricular dysfunction is attributed to a chronic decrease in myocardial blood flow without infarction is often difficult but important because such patients may benefit from surgical revascularization. Herein we describe a patient with severe left ventricular dysfunction who had appreciable resting wall motion abnormalities; tomographic thallium-201 myocardial scintigraphy performed while the patient was resting identified viable myocardium. Subsequent revascularization improved regional and global left ventricular function considerably.

Reduced HDL2 cholesterol subspecies and elevated postheparin hepatic lipase activity in older men with abdominal obesity and asymptomatic myocardial ischemia

Silent myocardial ischemia (SI), an asymptomatic manifestation of coronary artery disease (CAD), was identified in 10% of apparently healthy nonsmoking, nondiabetic older (60 +/- 7 years, mean +/- SD) men with normal plasma cholesterol levels. We hypothesized that in the absence of other major risk factors for CAD, the men with SI would have reduced plasma levels of high density lipoprotein (HDL) and HDL2 subspecies due to an upper-body fat distribution (waist-to-hip ratio [WHR]), hyperinsulinemia, and abnormal postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities. Compared with 47 normal control subjects of similar age, obesity, and maximal aerobic capacity, the 18 men with SI had higher plasma triglyceride (TG) (162 +/- 71 versus 102 +/- 39 mg/dl, p less than 0.001) and lower HDL-C (33 +/- 6 versus 37 +/- 7 mg/dl, p less than 0.02) levels with no difference in low density lipoprotein cholesterol level. The HDL2b and HDL2a subspecies measured by gradient gel electrophoresis were also lower in the men with SI (p less than 0.01). The plasma glucose and insulin responses during an oral glucose tolerance test were the same in both groups. Postheparin plasma HL activity was significantly higher in 12 men with SI than in 41 control subjects (34 +/- 8 versus 27 +/- 10 mumol/ml.hr-1, p less than 0.03) and was correlated with log insulin area (r = 0.36, p less than 0.05) and WHR (r = 0.32, p less than 0.05) in the control subjects but not in the men with SI. In the control group, the percent HDL2b subspecies was correlated inversely with postheparin plasma HL activity (r = -0.46, p less than 0.01, n = 41) as well as WHR (r = -0.49, p less than 0.001, n = 47) and log insulin area (r = -0.37, p less than 0.05, n = 47) but not in the men with SI. Postheparin LPL activity was the same in both groups of men and did not correlate with HDL, WHR, insulin, or plasma TG levels. As the control subjects and men with SI had comparable degrees of abdominal obesity and hyperinsulinemia, these results suggest that the reduced HDL-C levels in men with SI may be related to elevations in HL activity. Thus, abdominal obesity, hyperinsulinemia, elevated TG levels, and low HDL-C and HDL2 subspecies levels may predispose these older men to atherosclerosis.

Modern approaches to the diagnosis of coronary artery disease

Atherosclerotic coronary artery disease is a serious clinical problem. Clinicians dealing with patients can make a diagnosis of coronary disease in several ways. Unfortunately all too often the diagnosis is made via sudden death or acute myocardial infarction. At other times the diagnosis is made by evaluation of patients with symptoms--usually symptoms of angina or anginal equivalents. The great clinical and epidemiologic challenge of the coming years is to recognize that education and evaluation of persons with no symptoms or signs of coronary disease, but with risk factors for it, can and should be a focus of major efforts to reduce the number one cause of death in our society.

Biological risk factors for sudden death in patients with coronary artery disease and without heart failure

In a study of biological risk factors for sudden death in patients with coronary artery disease, 320 patients were, prospectively, recruited and followed-up over two years. None of the patients had heart failure or recent myocardial infarction. The following variables were recorded: previous acute myocardial infarction, hypertension, smoking habits, ventricular arrhythmia; the angiographic variables included: left ventricular ejection fraction, Jenkins' and mean atherosclerotic scores; lipid profile: cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoproteins Al and B; hemostatic profile: fibrinogen, fibrinopeptide A, antithrombin III, factor VIII antigen, factor VIII coagulant, protein C, plasminogen, alpha 2-antiplasmin, euglobulin clot lysis time and tissue plasminogen activator before and after venous occlusion, tissue plasminogen activator inhibitor, platelet factor 4, beta-thromboglobulin. During the follow-up period, 12 of the patients died suddenly. In these patients, ejection fraction was lower: 49 +/- 16% versus 61 +/- 14% for the other patients (P less than 0.02), fibrinogen higher: 3.9 +/- 0.8 g/l versus 3.5 +/- 0.8 for the living patients (P less than 0.05) and protein C lower: 89 +/- 39% versus 111 +/- 39% (P = 0.06) for the other patients. In multivariate analysis: lower ejection fraction (P less than 0.008), older age (P less than 0.03) and lower protein C (P less than 0.01) were correlated with sudden death. Among the patients with coronary artery disease, the raised fibrinogen and the decreased protein C appeared to be risk factors for sudden cardiac death. These alterations reflected a prothrombotic state which might increase the ischemic risk, due to an acute thrombosis, leading to the fatal ventricular arrhythmia. Determination of these hemostatic variables might be a useful adjunct for assessment of the vital prognosis of patients with coronary artery disease, especially the risk of sudden death in addition to other known clinical, electrocardiographic, hemodynamic risk factors. This would also guide both the instigation of complementary investigations and appropriate therapy in such high risk group of patients.

The Tromsø Study: associations between self-reported arrhythmia, psychological conditions, and lifestyle

In a survey, 19222 males and females aged 12-64 answered a question about sudden changes of heart rate or rhythm during the preceding year. The prevalence of reported arrhythmia was 12.4% in males and 17.2% in females. Multiple logistic regression was performed with self-reported arrhythmia as the dependent variable and psychological, lifestyle, and coronary risk factors as independent variables. The highest odds ratio for reported arrhythmia concerned poor compared with excellent health status; 3.86 in males and 2.98 in females. The relative risk for reported arrhythmia according to frequency of physician consultations was 2.28 in males and 1.70 in females, and odds ratios in both sexes were significant for psychological problems and smoking. The findings suggest that attention should be paid to the psychological conditions and lifestyle of patients who report irregular heartbeats. Self-reported arrhythmia may be a minor problem from a clinical point of view, but we still do not know its prognostic implications. Further work is necessary to determine the predictive strength of self reported arrhythmia for morbidity and mortality.

The influence of sex and different segments of thoracic aorta on bioactive aortic substance (BAS) and prostacyclin (PGI2) synthesis

BAS is a protein generated by aortic rings isolated from rats. Our previous results clearly established that BAS inhibits platelet aggregation and modifies vascular tone. We have now examined the effect of separated segments of thoracic aorta and the effect of sex on the release of the BAS and PGI2. We evaluated three different segments of thoracic aorta: A = aortic arch, B = the upper segment and C = the lowest segment of the thoracic aorta. We measured the release of BAS and PGI2 from them. The BAS production increased in the first segment (A) when compared with the other two (B and C), whilst PGI2 production was the same along the thoracic aorta. On the other hand female and male thoracic aorta produced the same levels of BAS and 6-keto PGF1 cm.

Sudden cardiac death: etiologies, pathogenesis, and management

Sudden death claims an estimated 350,000 lives per year in the United States. When death occurs within 1 hour of the onset of symptoms, 90% are the result of ventricular tachyarrhythmias. The majority of victims are middle-aged men with coronary artery disease, but in approximately 25%, sudden death is the presenting manifestation of their problem. In some populations, the detection of premature ventricular complexes (PVCs) by ambulatory monitoring is predictive of an increased risk of sudden death. However, the arrhythmia that best predicts this risk is unclear, and ambient arrhythmias are only a modest marker of this risk. Therapy to suppress asymptomatic PVCs has not been shown to be effective in preventing sudden death, and in some cases, lethal arrhythmias can be prevented without significant effects on ambient arrhythmias. Other risk markers such as depressed left ventricular function and the presence of low-amplitude, long-duration, late potentials recorded on a signal averaged electrocardiogram are more powerful predictors of risk than are PVCs. These latter findings in particular support the presence of areas of slow electrical conduction (a requirement for reentrant mechanism arrhythmias) and suggest that an abnormal electrical environment or "substrate" is the most important factor in this problem. The management of patients at risk for sudden death is controversial. While postinfarct survivors with arrhythmias constitute a population at increased risk, the absolute risk is only about 5% in the first year and has not been shown to be improved by conventional antiarrhythmic drugs. Small study size, arrhythmia variability, ill-defined end points, and proarrhythmia may partially explain this apparent lack of efficacy. The prophylactic use of antiarrhythmic drugs other than beta-blockers to prevent sudden death in asymptomatic populations at risk is therefore of unproven benefit. By contrast, patients who have survived a life-threatening arrhythmia unrelated to an acute myocardial infarction have an approximately 30% risk of recurrence in the following year. In these patients, the use of ambulatory monitoring to guide therapy is limited by the high incidence of false-negative responses (lethal arrhythmia recurrence despite ambient arrhythmia suppression) and the lack of frequent spontaneous arrhythmias in many patients. In this patient population, electrophysiological testing can be used to prognosticate recurrence and gain insight into arrhythmia mechanism, stability, and hemodynamic tolerance. The technique is also useful in guiding both pharmacological and nonpharmacological therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Sudden cardiac death after aortic valve surgery: incidence and concomitant factors

A retrospective analysis of 599 consecutive patients after aortic valve surgery aged 7-82 years (mean 56) was performed. During a follow-up of 1-14 years (mean 4.7 years) a 4-week perioperative mortality of 6.9% and a late annual mortality of 3.6% were observed. Sudden cardiac death was the most frequent single cause of death, accounting for 24% of all deaths. Patients dying suddenly were younger than patients dying from other causes (51 +/- 17 vs. 59 +/- 14 years, p less than 0.05) and showed more left ventricular hypertrophy by electrocardiographic criteria when compared with matched survivors (mean Estes score 5.2 +/- 2.4 vs. 2.8 +/- 1.9; p less than 0.01) and with patients dying nonsuddenly (mean Estes score 5.2 +/- 2.4 vs. 1.8 +/- 1.8; p less than 0.01). Ventricular premature beats in the resting electrocardiogram were more prevalent in patients dying suddenly than in matched survivors (55 vs. 20%; p less than 0.025) as well as in patients dying from other causes (55 vs. 25%; p less than 0.05). In addition, there were more intracardiac conduction disturbances and more ungrafted coronary vessels with insignificant stenoses at the time of surgery in sudden death patients. Our findings suggest that after aortic valve replacement patients with left ventricular hypertrophy, bundle-branch block, and ventricular premature beats in the resting electrocardiogram are at increased risk for sudden cardiac death. A possible etiological role of concomitant coronary artery disease must be considered.

Cardiovascular risk factors and graded treadmill exercise endurance in healthy adults: The Framingham Offspring Study

To help describe the association between exercise endurance and cardiovascular risk factor profiles, 2,606 young and middle-aged healthy adults in the Framingham Offspring Study were given submaximal treadmill tests. For both men and women, exercise endurance was inversely related to resting heart rate (p less than 0.001), body mass index (p less than 0.001), systolic blood pressure (p less than 0.001) and blood glucose (p less than 0.01), and positively related to high density lipoprotein (HDL) cholesterol (p less than 0.05). In men, cigarette smoking (p less than 0.05), high levels of total cholesterol (p less than 0.01) and very low density lipoprotein (VLDL) cholesterol (p less than 0.001) were also associated with poor exercise endurance. After adjusting for age, resting heart rate and body mass index, significant independent associations persisted for HDL cholesterol (p less than 0.05) in both sexes and for systolic blood pressure, VLDL cholesterol, blood glucose and cigarette smoking in men (p less than 0.05). Risk factors associated with overt cardiovascular disease in older individuals are also associated with poor exercise endurance in those who are younger and asymptomatic.

The hibernating myocardium

The hibernating myocardium refers to resting LV dysfunction due to reduced coronary blood flow that can be partially or completely reversed by myocardial revascularization and/or by reducing myocardial oxygen demand. It is different from the stunned myocardium. Methods for its detection are not yet perfect. Hibernating myocardium has been demonstrated to be present in several clinical subgroups of patients; however, currently its full clinical presence and impact are not adequately defined.

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.

Predictors of sudden death up to 18 years after a first attack of unstable angina or myocardial infarction

Factors related to the occurrence of sudden death were examined in 551 men aged less than 60 years who survived a first attack of unstable angina or myocardial infarction by at least 28 days. There were 301 deaths over an average follow up period of 9.4 years and 138 (46%) of these were sudden. Life table techniques permitted the estimation of mortality up to 18 years after the index event. The proportion of sudden deaths showed a decrease with length of follow up. In those who were non-smokers and in those aged less than 45 years on admission sudden deaths in the first two years were very common (80% (95% confidence interval: 69%-91%) and 79% (95% confidence interval: 68%-90%) respectively). The proportion of sudden deaths in the remaining 16 years of follow up was related inversely to age at initial attack. After the first two years of follow up sudden death rates were similar in those who continued to smoke and those who stopped smoking, although those who continued to smoke had a significantly higher overall mortality. The risk of sudden death should be borne in mind when planning the investigation and rehabilitation of young and non-smoking subjects presenting with a first coronary event.

Blood rheology in general medicine and surgery

Traditionally, blood rheology tests have been used in diagnosis and monitoring of infection, rheumatic diseases and malignancy, and are still of clinical value in these conditions. In the last twenty years, clinical and epidemiological studies have shown that the haematological determinants of blood flow resistance (haematocrit, fibrinogen, white cell count and altered red and white cell rigidity) are also associated with nutritional, metabolic, endocrine and vascular disorders. Decreased red cell deformability may contribute to reduced red cell survival and anaemia in burns, malaria, liver disease and kidney failure. In trauma and inflammatory disease, overt hyperviscosity is usually prevented by vasodilatation and reduction in the haematocrit. However, low-flow states may arise systemically from haemoconcentration (contracted plasma volume, Chapter 3) in severe burns, inappropriate red cell transfusion, or dehydration due to illness; systemically in circulatory shock; and locally in venous thrombosis or arterial disease. In such circumstances, the intrinsic flow resistance of blood may perpetuate flow disturbance, ischaemia and thrombosis. Conversely, optimal levels of haematocrit, fibrinogen and white cell count may be lower than normal in low-flow states. Haemodilution by colloid infusion is beneficial in burns, shock, major surgery, prevention of postoperative venous thrombosis, chronic stable claudication and possibly in acute stroke and retinal vein thrombosis. Plasma exchange may be beneficial in severe Raynaud's phenomenon. Defibrination with ancrod is effective in prevention and treatment of venous thrombosis but its role in arterial disease is unproven. The benefits of streptokinase therapy in venous thrombo-embolism and acute myocardial infarction may be partly rheological, due to fibrinogen depletion. Drugs with rheological effects may be beneficial in intermittent claudication.

The electrocardiogram in prediction of sudden death: Framingham Study experience

The influence of ECG abnormalities on the incidence of sudden cardiac death is examined in the Framingham Study cohort and is compared with the effect of known cardiovascular risk factors. Although many individual ECG abnormalities are associated with SD, multiple regression analysis, including non-ECG variables, leaves fewer independently related ECG sudden death risk factors: ECG-MI and IVB in those with overt CHD, LVH and tachycardia in all men and in women without CHD, and nonspecific ST-T abnormalities only in men. VPBs appear to be without an independent influence. Inclusion of ECG variables in the predictive model for SD has little effect on identifying those at risk for sudden unexpected death, but it improves substantially the predictive value in persons with known CHD.