The effects of atrial pacing on the signal-averaged electrocardiogram in patients with coronary artery disease

The effects of atrial pacing on the signal-averaged electrocardiogram were studied in 14 patients with remote myocardial infarction and a history of cardiac arrest or sustained ventricular tachycardia (group I) and in 13 patients with coronary artery disease and no history of sustained ventricular tachyarrhythmia (group II). Recordings of the signal-averaged electrocardiogram were obtained at control and during atrial pacing at rates of 80, 100, and 120 beats/min. All patients had recordings analyzed from at least two paced rates. At control, the mean high frequency total duration of the QRS complex (HFTD) was significantly longer in group I versus group II patients (123 +/- 5.6 versus 111 +/- 3.5 msec, p less than 0.05). Although the duration of the QRS signal under 40 microV (D40) was higher in group I versus group II patients (42 +/- 4.7 versus 32.4 +/- 3.5 msec) and the root mean square amplitude of the terminal 40 msec QRS (RMSA) was lower in the group I patients (27 +/- 7.5 versus 38.1 +/- 8.8 microV), these differences did not achieve statistical significance. There was no effect of atrial pacing on the measured signal-averaged parameters of HFTD, D40, and RMSA. Although there was a difference between group I and group II at each paced rate analyzed, atrial pacing did not help to further stratify the groups. In patients with coronary artery disease, atrial pacing is not a useful method of stratifying high-risk patients. Changes in serial signal-averaged electrocardiograms from the same patient are not due to heart rate variability.     

The signal-averaged electrocardiogram in predicting coronary artery disease

The ability to noninvasively detect coronary artery disease (CAD) in patients undergoing diagnostic cardiac catheterization was studied using a signal-averaged electrocardiogram. An initial study of 13 patients revealed that a QRS duration greater than or equal to 100 msec, a root mean square voltage in the terminal 40 msec of the QRS less than 50 microV, and a low amplitude signal (LAS) duration greater than 28 msec were suggestive of CAD. These parameters were then used prospectively to examine 40 consecutive patients with chest pain of undetermined etiology referred for cardiac catheterization. Patients with CAD had significantly longer filtered QRS and LAS durations and lower root mean square voltages compared with patients without CAD. The sensitivity, specificity, and positive predictive value of a single parameter ranged from 62% to 76%, 74% to 89%, and 75% to 87%, respectively. Thus the signal-averaged electrocardiogram may be a useful tool in evaluating patients for the presence of CAD.     

Short-term effect of coronary artery bypass grafting on the signal-averaged electrocardiogram

Ventricular late potentials at the end of the QRS can be detected on the body surface during sinus rhythm by recording a signal-averaged electrocardiogram (SAECG). In patients with coronary artery disease, these late potentials have been shown to be markers for spontaneous or inducible ventricular tachycardia, or both. The short-term (before and 10 +/- 4 days after coronary revascularization) influence of coronary artery bypass grafting (CABG) on the quantitative SAECG variables was studied in 40 patients with chronic coronary artery disease. Twenty-five of these patients had a previous myocardial infarction. In the 15 patients without previous myocardial infarction, no abnormal SAECG indexes were recorded before CABG and no change in the quantitative SAECG variables was observed after surgery. In the patients with a previous myocardial infarction, 7 (28%) had a late potential before CABG. After CABG, 5 (71%) patients remained late potential-positive, whereas the other 2 (29%) lost their late potential. The mean values of their SAECG variables improved after coronary revascularization. In the entire group of postmyocardial infarction patients, the high-frequency QRS duration had shortened (p less than 0.01) after CABG (the other SAECG indexes did not change). The postoperative arrhythmic complications (transient atrial fibrillation, new onset of ventricular couplets) tended to be more frequent in the postmyocardial infarction group and in patients with late potentials. Our findings suggest that the reported increase in ventricular arrhythmias after CABG is probably not related to a change in the arrhythmogenic substrate for ventricular reentry but is associated with changes in the arrhythmogenic milieu.     

Effects of exercise on the signal-averaged electrocardiogram in coronary artery disease

The effects of exercise on the signal-averaged electrocardiogram (SAECG) were investigated in 52 patients with stable coronary artery disease. The SAECG was recorded before and immediately after the exercise test and analyzed at 25 to 250 Hz and 40 to 250 Hz. All patients had SAECG with noise level less than or equal 0.8 microV at 25 Hz and less than or equal to 0.6 microV at 40 Hz and with the difference in noise level between control SAECGs and SAECGs after exercise less than or equal to 0.2 to 0.3 microV. Twenty-eight patients developed ST changes consistent with transient subendocardial ischemia that persisted during the SAECG recording after exercise. There was no significant difference between control SAECGs and SAECGs after exercise in patients with or without a positive exercise test. The absence of significant change on the SAECG was not related to the presence or absence of prior myocardial infarction, site of infarction, development of exercise-induced ventricular arrhythmias or presence of an abnormal recording at baseline. These data suggest that exercise-induced electrophysiologic changes and ventricular arrhythmias may not be related to the anatomic-electrophysiologic substrate that underlies late potentials on the SAECG.     

信号平均心电图预测冠心病患者心律失常事件的前瞻性研究

目的：评价心室晚电位（ＶＬＰ）预测心律失常事件（ＡＥ）的价值。方法：对２６１例冠心病患者进行２４小时Ｈｏｌｔｅｒ和信号平均心电图（ＳＡ－ＥＣＧ）检测，其中ＡＭＩ患者于发病后２～４周行ＳＡ－ＥＣＧ检测。所有患者均进行临床随访。结果：２６１例冠心病患者中ＶＬＰ阳性率１４９％，随访１３６±６９（４～３６）月，发生ＡＥ１８例。ＶＬＰ阳性组ＡＥ发生率２９７％，明显高于ＶＬＰ阴性组ＡＥ发生率３６％（Ｐ＜００００１）。发生ＡＥ组ＶＬＰ阳性率６１１％，明显高于未发生ＡＥ组ＶＬＰ阳性率１２３％（Ｐ＜０００１）。ＶＬＰ时域分析预测冠心病患者发生ＡＥ的敏感性６１１％、特异性８７７％、阳性预测值２９７％、阴性预测值９６４％、准确性８５６％。结论：ＶＬＰ预测ＡＥ有较高的敏感性、特异性和准确性。ＶＬＰ有助于冠心病（尤其心肌梗死）患者的危险性分层。     

The ratio of eicosapentaenoic acid to arachidonic acid is a critical risk factor for acute coronary syndrome in middle-aged older patients as well as younger adult patients

BackgroundCoronary risk factors for the onset of acute coronary syndrome (ACS), including polyunsaturated fatty acids (PUFAs), in younger adult patients may be different from those in older patients.Methods and resultsWe enrolled 578 patients who underwent coronary angiography at Fukuoka Saiseikai Hospital, and divided them into a younger adult group (YG) (<50 years, n = 47) and a middle-aged older group (OG) (≥50 years, n = 531). In a multivariate analysis, lower levels of high-density lipoprotein cholesterol and the ratio of eicosapentaenoic acid (EPA) to arachidonic acid (AA) (EPA/AA), and less aspirin, oral hypoglycemic agent, and calcium channel blocker (CCB) use were independent risk factors for ACS in all patients. In YG, lower levels of EPA/AA and less angiotensin II receptor blocker/angiotensin-converting enzyme inhibitor use were the independent risk factors. In OG, smoking, lower levels of EPA/AA, less aspirin and CCB use were the risk factors. While lower levels of EPA/AA was the only risk factor for ACS that was common to all patients, YG and OG, docosahexaenoic acid/AA was not associated with ACS in YG and OG.ConclusionsLower level of EPA/AA is a common critical risk factor for ACS in middle-aged older patients as well as younger adult patients. Some of the risk factors for the onset of ACS in younger patients were different from those in older patients.     

饮食中增加多不饱和脂肪酸对冠状动脉硬化性心脏病患者的影响

目的探讨饮食中增加多不饱和脂肪酸(PUFA)与冠状动脉硬化性心脏病(CHD)患病风险的关系。方法通过计算机检索PubMed、CENTRAL、中国生物医学文献数据库系统(CBM)、中国期刊全文数据库(CNKI)、万方数据库、中文科技期刊全文数据库(VIP)等,收集国内外公开发表的关于食物中增加PUFA与CHD患病风险关系的临床随机对照研究(RCT)。采用系统评价方法对各研究结果进行分析,计算其合并风险比(RR)和95%置信区间(CI)。结果检索到符合要求的文献7篇,包括13 257例受试者,在这些受试者中共有969例发生了CHD。在入选的研究中干预组受试者PUFA的平均摄入量为总热量的14.4%,对照组受试者PUFA的平均摄入量为总热量的5.0%。荟萃分析显示,饮食中增加PUFA可以明显减少CHD的患病风险(Z=13.15,P=0.000);干预组受试者CHD的患病风险可以减少19%(RR=0.81,95%CI:0.69～0.94,Z=13.5,P=0.000)。结论饮食中增加PUFA可以显著降低CHD患病风险。     

Effects of amiodarone on the P-wave triggered signal-averaged electrocardiogram in patients with paroxysmal atrial fibrillation and coronary artery disease

The effects of a 6-week treatment with amiodarone on the P-wave triggered signal-averaged electrocardiogram in patients with paroxysmal atrial fibrillation and coronary artery disease have been studied. Amiodarone favorably influences P-wave triggered signal-averaged electrocardiographic parameters, predominantly in patients in whom amiodarone is effective in preventing paroxysmal atrial fibrillation.     

The long-term effects of individual cardiac rehabilitation in patients with coronary artery disease

BackgroundThe positive effects of cardiac rehabilitation have been repeatedly described and are well-known over the short- and middle-term periods. However there is less knowledge about long-term outcomes in patients with chronic stable coronary artery disease.AimThe aim of this study was to evaluate the long-term outcome of individual cardiac rehabilitation in patients with coronary artery disease.MethodsOne hundred fifty-two patients with stable coronary artery disease were retrospectively divided into two groups according to their adherence to individual physical activity recommendations, regardless of their participation in guided cardiac rehabilitation training. The IT+ group which participated in individual exercise programmes according to recommendations was compared with patients who declined these activities (the IT− group). The median follow-up period was 12.7 years.ResultsThe individual training had no long-term effect on survival after being checked for other possible contributing factors, but the multivariate analysis showed a significant association with the occurrence of cardiac events like myocardial infarction, unstable angina, coronary revascularization and hospitalization for heart failure: HR (95% CI) 0.51 (0.30–0.89); p = 0.017.ConclusionHome based cardiac rehabilitation and regular physical activity significantly improve long-term cardiac morbidity in patients with coronary artery disease.     

Predicting efficacy of dipeptidyl peptidase‐4 inhibitors in patients with type 2 diabetes: Association of glycated hemoglobin reduction with serum eicosapentaenoic acid and docosahexaenoic acid levels

This study was initiated to identify clinical and dietary parameters that predict efficacy of dipeptidyl peptidase‐4 inhibitors. A total of 72 untreated Japanese patients with type 2 diabetes who received DPP‐4 inhibitors (sitagliptin, alogliptin or vildagliptin) for 4 months were examined for changes of glycated hemoglobin (HbA_1c) and body mass index (BMI), and self‐administered 3‐day food records, as well as serum levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). DPP‐4 inhibitors significantly reduced HbA_1c (before initiation of DPP‐4 inhibitors 7.2 ± 0.7%, 4 months after initiation of DPP‐4 inhibitors 6.7 ± 0.6% [paired t‐test, P < 0.01 vs before]). Multiple regression analysis showed that changes of HbA_1c were significantly correlated with baseline HbA_1c, as well as estimated intake of fish. Furthermore, changes of HbA_1c were significantly correlated with serum levels of EPA (r = −0.624, P < 0.01) and DHA (r = −0.577, P < 0.01). HbA_1c reduction by DPP‐4 inhibitors is significantly correlated with estimated intake of fish and serum levels of EPA and DHA. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00214.x, 2012)     

Long-term treatment with eicosapentaenoic acid improves exercise-induced vasodilation in patients with coronary artery disease.

We have previously shown that long-term treatment with eicosapentaenoic acid (EPA) improves endothelium-dependent vasodilation of the atherosclerotic arteries in both animals and humans. The aim of the present study was to examine whether EPA treatment also improves metabolic vasodilation evoked by exercise in patients with coronary artery disease (CAD). Forearm blood flow (FBF) was measured by strain gauge plethysmography in 10 patients with stable CAD, before and 3 months after oral treatment with EPA (1,800 mg/kg). FBF was measured at rest and during intra-arterial infusion of acetylcholine or sodium nitroprusside, before and after intra-arterial infusion of NG-monomethyl-L-arginine (L-NMMA, an inhibitor of nitric oxide (NO) synthesis). A rhythmic handgrip exercise was also performed for 3 min before and after L-NMMA, and FBF was measured for 3 min just after the handgrip exercise. These protocols were repeated after the long-term treatment with EPA for 3 months. The long-term treatment with EPA significantly improved the FBF responses to acetylcholine (p < 0.01), which was significantly reduced by acute administration of L-NMMA (p < 0.01). By contrast, the EPA treatment did not affect the endothelium-independent responses to sodium nitroprusside. Metabolic increases in FBF caused by the handgrip exercise were not significantly decreased by L-NMMA before the EPA treatment. The EPA treatment significantly augmented the exercise-induced increases in FBF (p < 0.05) and L-NMMA acutely abolished this augmentation (p < 0.01). These results indicate that long-term treatment with EPA improves both endothelium-dependent and exercise-induced forearm vasodilations in patients with CAD and that NO is substantially involved in the EPA-induced improvement of the FBF responses in patients with CAD.     

Correlation between the signal-averaged electrocardiogram and electrophysiologic study findings in patients with coronary artery disease and sustained ventricular tachycardia

Ventricular late potentials at the end of the surface QRS, detected on the signal-averaged electrocardiogram (SAECG) have been shown to be markers for spontaneous and/or inducible ventricular tachycardia (VT) in patients with coronary artery disease (CAD). We examined the correlations between electrophysiologic study (EPS) findings and SAECG indexes in 50 patients with chronic CAD with documented spontaneous VT/ventricular fibrillation (VF), who had either syncope (24 patients) or aborted sudden cardiac death (SCD). The prevalence of late potentials was significantly higher in the syncope patients (75%) compared with the SCD group (46%) (p less than 0.05). No correlation was found between the ventricular refractoriness and the SAECG indexes. There was a significant difference in quantitative SAECG indexes comparing the induction mode of the sustained VT/VF by single and double versus triple extrastimuli; the types of the induced VT (sustained monomorphic, sustained pleomorphic or VF, noninducible); and the cycle length of the induced sustained monomorphic VT with the high frequency QRS duration (QRSD). In conclusion, differences in prevalence and characteristics of ventricular late potentials were found between patients with syncope and with SCD. The degree of abnormality of SAECG indexes correlated with the type and the mode of induction of sustained VT. The magnitude of QRSD of the SAECG correlated with the cycle length of monomorphic VT. The above findings suggest that in patients with CAD and sustained VT/VF the SAECG variables are related to the area of reentry.     

High hexacosanoic acid levels are associated with coronary artery disease

Aims

Levels of saturated very long chain fatty acids (VLCFAs) are associated with coronary risk factors, including metabolic syndrome (MS), atherogenic lipoproteins, and systemic inflammation. However, the relationship between circulating levels of saturated VLCFA and coronary artery disease (CAD) remains unclear.

Method

We enrolled 100 consecutive CAD patients and 40 age-, gender-, and body mass index (BMI)-matched healthy control subjects. The levels of hexacosanoic acid (C26:0), a VLCFA, in whole blood were measured by gas–liquid chromatography mass spectrometry.

Results

C26:0 levels were significantly higher in the CAD group than in the control group (2.42 ± 0.32 vs. 2.27 ± 0.24 μg/ml, P = 0.01) and positively correlated with BMI (r = 0.23, P = 0.008), triglyceride levels (r = 0.22, P = 0.01), and hypertension (P = 0.01). CAD patients with MS showed the highest C26:0 levels adjusted by hematocrit. Furthermore, adjusted C26:0 levels in CAD patients without MS were higher than those in controls (P = 0.02), suggesting that C26:0 levels increased with the presence of CAD independent of MS. Our multivariate analysis revealed that high C26:0 levels in whole blood is an independent marker for CAD even after adjustment for age, gender, BMI, lipid profiles, fasting plasma glucose, and blood pressure.

Conclusion

High C26:0 levels in whole blood may be an independent marker for identifying the risks of CAD.     

叶酸对冠心病患者支架术后血管内皮功能的影响

目的 探讨叶酸能否改善冠心病患者支架术后的血管内皮功能.方法 共184例冠心病患者,在行冠状动脉支架术后,随机分为叶酸治疗（20 mg/d）92例和对照组92例.随访6个月,观察两组同型半胱氨酸水平.以超声测定肱动脉血流介导的舒张功能（FMD）变化来评价血管内皮功能,并观察两组间的差别.结果 叶酸治疗组血浆同型半胱氨酸水平低于对照组[（8.83±3.33）μmol/L比（13.18±5.08）μmol/L,P＜0.01].叶酸治疗后,FMD由（4.72±1.73）%增加至（8.54±1.45）%,P＜0.01.结论 叶酸治疗可能通过降低同型半胱氨酸以外的途径改善血管内皮功能,对介入治疗后的冠心病患者发挥潜在益处.     

厄贝沙坦对冠心病患者非心脏手术围术期的影响

目的:探讨血管紧张素Ⅱ受体拮抗剂(AngiotensinⅡ receptor blocker ARB)类降压药厄贝沙坦应用对有心肌缺血病变患者的围术期保护作用的临床疗效。方法:60例行非心脏手术(noncardiac surgery)的冠心病(coronary artery disease CAD)患者,美国麻醉师协会分级(American society of anesthesiologists classification,ASA classification)Ⅱ-Ⅲ级,随机分为厄贝沙坦(A组)、对照组(B组),每组各30例。分别测定患者麻醉前(T0)、术后3d(T1),术后10d(T2)的心肌肌钙蛋白I(cTnI)的浓度,并统计心电学变化状况、心脏事件发生率。结果:在T1、T2时点,所有组别cTnI浓度与T0相比较均升高(P0.05),T1时点的A组(0.157±0.120)μg/L及B组(0.161±0.142)μg/L患者血cTnI浓度在2组间差异无统计学意义(P0.05),T2时点的cTnI浓度及阳性率B组(0.268±0.225)μg/L高于A组〔(0.098±0.089)μg/L,P0.05〕差异有统计学意义。术后短期内A组10例(33.3%),较B组16例(53.3%)心电学变化及心脏事件发生率低。结论:厄贝沙坦对冠心病患者可能降低围术期cTnI上升程度,减少心电学变化及心脏事件发生率,对心肌具有保护作用。     

冠心病患者脉搏波传导速度与心功能的相关性

目的研究冠心病患者脉搏波传导速度(PWV)与心功能的相关性。方法选取经冠状动脉造影确诊为冠心病者366例,收集一般临床资料,测定肱踝PWV(baPWV),行超声心动图检查等,同时在入选患者中选取44例行多普勒组织成像。结果冠心病患者baPWV与室间隔厚度(r=0.306,P<0.001)、左心室后壁厚度(r=0.365,P<0.001)、左心室质量分数(r=0.293,P<0.001)和E/Ea(r=0.458,P<0.01)呈显著正相关,与射血分数(r=-0.210,P<0.001)、Ea(r=-0.428,P<0.01)、Ea/Aa(r=-0.331,P<0.05)呈显著负相关。在除外高血压等的影响后,偏相关分析显示,baPWV与室间隔厚度(r=0.231,P<0.001)、左心室后壁厚度(r=0.320,P<0.001)、左心室质量分数(r=0.233,P<0.001)、射血分数(r=-0.182,P<0.001)、Ea(r=-0.429,P<0.01)、Ea/Aa(r=-0.339,P<0.05)、E/Ea(r=0.437,P<0.01)仍显著相关。冠心病患者不同心功能分级组间的baPWV差异有统计学意义(P<0.05),baPWV随临床心功能恶化而升高。结论 baPWV与冠心病患者左心室肥厚、左心室收缩和舒张功能、临床心功能均具有相关性,baPWV可以作为评估冠心病患者心功能的一个指标。     

Comparative effects of ventricular resynchronization therapy in heart failure patients with or without coronary artery disease

In patients with advanced heart failure, intraventricular conduction delay (IVCD) and left ventricular systolic dysfunction (LVSD), multisite cardiac pacing can be proposed as an additive treatment. The aim of this study was to assess the clinical effectiveness of atrioventricular pacing according to the etiology of LVSD, by comparing the outcome of patients with and without coronary artery disease. Between August 1997 and November 1998, 103 patients were included in the InSync trial and received a biventricular pacemaker and a specifically designed left ventricular pacing lead. Baseline evaluation (12 lead ECG, New York Heart Association Class, quality of life (QOL) and distance walked during the 6 min walk test) was repeated in survival patients at 1, 3, 6 and 12 months after pacemaker implantation. Patients were split in two groups, ischemic (N = 48) and non-ischemic (N = 55), according the result of a recent coronary angiography, the existence of coronary angioplasty or coronary artery bypass or the history of a prior myocardial infarction. RESULTS: The mortality rate was similar in the two groups with a mean 12 months actuarial survival rate of 78%. Nevertheless, the delay between the death and the pacemaker implantation was significantly higher in the non-ischemic group. A significant reduction in QRS duration and a significant improvement in NYHA class (-1.5). QOL score (-50%) and 6 min walking test (+18%) were observed similarly in the two groups. CONCLUSION: This study shows that biventricular pacing improves significantly functional status of patients with LVSD, IVCD and advanced heart failure, regardless the etiology of the cardiomyopathy, ischemic or not, without over-mortality in ischemic patients.     

A free fatty acid tolerance test identifies patients with coronary artery disease among individuals with a low conventional coronary risk profile

This study investigated whether the presence of coronary artery disease (CAD) in patients with a low conventional coronary risk profile is associated with perturbations of free fatty acid (FFA) metabolism. All patients studied were non-smokers, normoglycemic, normotensive, nonobese, and had triglycerides, low-density lipoprotein and high-density lipoprotein (HDL) cholesterol in the reference ranges. An FFA tolerance test was designed, consisting of a heparin injection 4 h after an oral fat load which induced a marked increase in plasma FFA concentrations. Measurements were made before the fat load, after 4 h (immediately before heparin injection), and after 4.5, 8, and 10 h. The test was carried out in 28 male CAD patients and in 25 male controls free of CAD as verified by coronary angiography. In the fasting state the two groups showed no differences in conventional risk factors with the exception of HDL cholesterol (patients 0.97 ± 0.04 mmol/l, controls 1.13 ± 0.05 mmol/l, P = 0.013). During the test the best discriminator found was FFA at 8 h (P = 0.0009) and, very pronounced, at 10 h (P = 0.000). We conclude that perturbed FFA metabolism in an FFA tolerance test can indicate the presence of CAD in men with a low conventional coronary risk profile, possibly as an early indicator of the metabolic syndrome. Received: May 1, 2001 / Accepted: October 13, 2001