QT dispersion as a risk factor for sudden cardiac death and fatal myocardial infarction in a coronary risk population.

OBJECTIVE: To evaluate the efficacy of head up tilt guided treatment with metoprolol and clonidine in preventing the recurrence of syncope in patients with malignant vasovagal syncope. PATIENTS: 20 patients (9 men and 11 women, mean age 33 (SD 17), range 14 to 62 years) with severe symptoms. DESIGN: Randomised double blind crossover trial; efficacy was assessed by head up tilt testing. RESULTS: Metoprolol was more effective than clonidine in abolishing syncope (19/20 v 1/20, P < 0.001) but clonidine showed some beneficial effects on time to syncope and severity of hypotension in 12 patients. During an average follow up of 15 (3) months there was a significant reduction in the recurrence of symptoms compared with the previous year in patients who had tilt up guided treatment (18 metoprolol, 1 clonidine). CONCLUSIONS: Treatment guided by head up tilting is a reliable method of treating patients with malignant vasovagal syndrome. Metoprolol was an effective long term treatment for preventing syncope. High doses were more effective and a careful dose titration period helped to minimise withdrawal symptoms and side effects.     

Hypertension as a risk factor for sudden cardiac death and nonfatal myocardial infarction. Working Group of CNR Study OD1

To evaluate long-term prognosis during medical treatment of hypertension associated with angina pectoris, a total of 1083 patients with angiographically-documented coronary artery disease were followed for a mean of 66 months. At the end of the study, follow-up was complete in 98% of all patients. Of the 1083 patients, 132 (12%) had hypertension and 951 (88%) were not hypertensive. During the follow-up period, there was a total of 15 deaths (11.3%) among the hypertensive population (vs. 61 or 6.4% in the nonhypertensives) as well as a higher incidence of nonfatal myocardial infarction (9.0% in the hypertensives vs. 3.7% in the nonhypertensives) (Figure 2). Six-year cumulative survival was 84% in the hypertensive patients as compared to 92% in the nonhypertensives. Among risk factors, historical data, clinical and catheterization findings, the only noninvasively-obtainable independent predictor of prognosis using multivariate analysis was hypertension (Table 3).     

Diabetes as a risk factor for sudden death

Although a family history of sudden death was a risk factor for sudden death in the Paris Prospective Study I, diabetes was also a strong risk factor, with a similar risk after accounting for other cardiovascular risk factors. Diabetes, however, was not a risk factor for death by myocardial infarction.     

Lipoprotein (alpha) as a risk factor for myocardial infarction]

Serum lipoprotein (alpha) [Lp(alpha)]was determined in 105 cases of myocardial infarction survivors (MIS). Lp(alpha) level in MIS was much more elevated as compared with that in healthy subjects and in a hypertension group. Lp(alpha) had no relation with apolipoprotein B and AI, cholesterol, triglyceride and high density lipoprotein cholesterol. It may be a significant and independent risk factor for coronary heart disease.     

Seasonal variation in sudden cardiac death after experimental myocardial infarction

The authors studied the incidence of sudden death by monitoring the ECG after ligation of the left anterior descending coronary artery in 184 dogs. A significant number of sudden deaths (46 dogs) occurred in the cold weather months, November-February (42%), compared to the summer months, July and August (6%). All deaths resulted from ventricular tachyarrhythmias (greater than or equal to 300/min) and occurred between 13 and 22 hours after coronary artery ligation. The survivors (138 dogs) were subjected to electrophysiological study, during which a significantly higher number showed induced sustained monomorphic ventricular tachycardia (VT) (heart rate greater than or equal to 300/min) during the winter months than during the summer months. Heart weight and infarct mass were not significantly different throughout the year. Higher sympathetic tone or catecholamine levels may account for the seasonal variation in sudden death during evolving myocardial infarction.     

Out-of-hospital sudden cardiac death following myocardial infarction in urban population

Samples of out patient sudden cardiac deaths in Kanagawa Urban prefecture from 1972-1987 and coronary risk factors were studied to determine the increase and/or decrease of myocardial infaction deaths. On the whole death from myocardial infarction increased chronologically, and the rate for females tended to be increased further. The age adjusted myocardial infarction deaths doubled over 10 years, while non-ischemic acute cardiac failure decreased with each generation. Other cardiac diseases tended to be reduced. Cigarette smoking was the highest in advanced countries in male. These findings suggest that deaths from myocard infarction approximately doubled in 10 years in all out-of hospital sudden cardiac deaths. Cigarette smoking from a young age was as great risk as future ischemic heart disease.     

老年陈旧性心肌梗死患者心性猝死危险性预测指标的探讨

目的探讨４项非创伤性检查指标对老年人陈旧性心肌梗死后心性猝死危险性的预测价值。方法老年人陈旧性心肌梗死７９例，分为猝死组（２２例）和非猝死组（５７例），对比分析两组间４项指标的差异。结果（１）猝死组的左室射血分数（ＬＶＥＦ）和心率变异性指数（ＨＲＶＩ）明显低于非猝死组（Ｐ＜０．０１），而ＱＴ离散度和２４小时动态心电图室性期前收缩（ＶＰＢｓ）＞３０个／小时的发生率在两组间差异无显著性。（２）Ｌｏｇｉｓｔｉｃ多因素回归分析显示ＬＶＥＦ是预测心性猝死危险性的独立指标。如以ＬＶＥＦ４５％为界分组，ＬＶＥＦ＜４５％组的ＶＰＢｓ＞３０个／小时的发生率明显高于ＬＶＥＦ＞４５％组（Ｐ＜０．０１），ＨＲＶＩ明显低于ＬＶＥＦ＞４５％组（Ｐ＜０．０５）。结论老年人心肌梗死伴左心功能不全者易发生心脏自主神经功能失调，诱发严重室性心律失常，导致心性猝死。     

Silent myocardial ischemia as a mechanism of sudden cardiac death

Sudden death, a major cause of mortality in the Western world, usually results from electrophysiologic phenomena in chronically damaged hearts with advanced coronary atherosclerosis. The exact pathophysiologic mechanisms are not known, but there is reasonable circumstantial evidence to implicate myocardial ischemia--clinically manifest or silent--as one of probably multiple factors of pathogenetic significance. This may be on the basis of coronary artery spasm, platelet aggregation, left ventricular dysfunction perpetuating a vicious circle of hypoperfusion and ventricular vulnerability to electrical instability. The increasing use and quality of continuous ambulatory electrocardiographic (Holter) monitoring have allowed improved detection of ST-segment changes and arrhythmias. The majority of sudden deaths result from ventricular tachyarrhythmias degenerating into ventricular fibrillation, and a more significant proportion of these than had been previously thought may be ischemically mediated. Importantly, as many as 20 to 25 per cent of the approximately 450,000 yearly terminal events represent bradyarrhythmias that may be preceded or accompanied by silent myocardial ischemia. Research is still required to determine the incidence, role, and mechanisms of silent myocardial ischemia in sudden death, with the hope that this common catastrophic event can be better prevented.     

Genetic profiling as a marker for risk of sudden cardiac death

PURPOSE OF REVIEW: Clinical trials provide evidence that an empirical approach of implantable cardioverter-defibrillator implantation in all heart failure patients (ejection fraction 相似文献   

Prediction of sudden cardiac death after myocardial infarction in the beta-blocking era

OBJECTIVES: This study assessed the predictive power of arrhythmia risk markers after an acute myocardial infarction (AMI). BACKGROUND: Several risk variables have been suggested to predict the occurrence of sudden cardiac death (SCD), but the utility of these variables has not been well established among patients using medical therapy according to contemporary guidelines. METHODS: A consecutive series of 700 patients with AMI was studied. The end points were total mortality, SCD, and nonsudden cardiac death (non-SCD). Nonsustained ventricular tachycardia (nsVT), ejection fraction (EF), heart rate variability, baroreflex sensitivity, signal-averaged electrocardiogram (SAECG), QT dispersion, and QRS duration were analyzed (n = 675). Beta-blocking therapy was used by 97% of the patients at discharge and by 95% at one and two years after AMI. RESULTS: During a mean (+/-SD) follow-up of 43 +/- 15 months, 37 non-SCDs (5.5%) and 22 SCDs (3.2%) occurred. All arrhythmia risk variables differed between the survivors and those with non-SCD (e.g., the standard deviation of N-N intervals was 98 +/- 32 vs. 74 +/- 21 ms [p < 0.001] and the QRS duration was 103 +/- 22 vs.89 +/- 16 ms [p < 0.001]). Sudden cardiac death was weakly predicted only by reduced EF (<0.40; p < 0.05), nsVT (p < 0.05), and abnormal SAECG (p < 0.05), but not by autonomic markers or standard ECG variables. The positive predictive accuracy of EF, nsVT, and abnormal SAECG as predictors of SCD was relatively low (8%, 12%, and 13%, respectively). CONCLUSIONS: The common arrhythmia risk variables, particularly the autonomic and standard ECG markers, have limited predictive power in identifying patients at risk of SCD after AMI in the beta-blocking era.     

Low heart rate variability is a risk factor for sudden cardiac death in type 2 diabetes

The purpose of this study is to examine the association between sudden cardiac death (SCD) and heart rate variability (HRV) in subjects with and without type 2 diabetes and to determine whether low HRV can predict SCD in type 2 diabetes. Subjects were 8917 consecutively examined persons (3089 diabetic, and 5828 nondiabetic subjects) aged 35-69 years who underwent a 75 g oral glucose tolerance test (OGTT) together with electrocardiography (ECG). HRV was calculated from the 12-lead ECG as the coefficient of variance for 100 R-R intervals (CV(R-R)). During a median observation period of 5.2 years, SCD occurred in 56 subjects (33 diabetic, and 23 nondiabetic). Among diabetic subjects, mortality from SCD tended to be higher in subjects with a low CV(R-R) (P=0.004). After adjustment for age, gender, systolic blood pressure, total cholesterol (TC), triglycerides (TG), BMI, ischemic ECG change, and smoking history, relative risk (RR) of SCD was 2.07 (95% CI 1.02-4.17) in diabetic subjects with a CV(R-R) <2.2% compared with those with a CV(R-R) > or =2.2%. Diabetic subjects with a CV(R-R) <2.2% had significantly higher cumulative mortality from SCD than those with a CV(R-R) > or =2.2% (P=0.007). In type 2 diabetes, a low CV(R-R) carried an increased risk of SCD.     

急性心肌梗死心脏骤停患者的院前急救探析

目的探讨急性心肌梗死心脏骤停院前急救特点及效果。方法本次共选取80例急性心肌梗死心脏骤停的患者作研究对象,均为我院急诊科2012年2月至2013年5月收治,行完善的院前急救,回顾分析临床资料。结果本次选取病例中,抢救成功48例,占60％,死亡32例,占40％。抢救成功患者年龄〉165岁占25％（4／16）,明显少于死亡组70．8％（17,24）,CPR、电除颤时间明显早于死亡组,气管插管人数抢救成功组为18．8％（3／16）,明显低于死亡组45．8％（11／24）,差异均有统计学意义（P〈0．05）。结论加强急救网络的配置,普及急救知识,对院前急救流程行完善建立,加强规范救治,可显著提高急性心肌梗死心脏骤停患者的救治成功率,保障患者生命安全,具有非常积极的意义,需引起各级部门重视。