Immediate and Day-to-Day Reproducibility of the Signal-Averaged Electrocardiogram in Patients with Coronary Artery Disease

The purpose of this study was to prospectively evaluate the immediate (5 minutes) and short-term (1 day) reproducibility of the signal-averaged electrocardiogram (SAECG) in patients with coronary artery disease. A total of 59 consecutive patients with coronary artery disease (50 male, 9 female, mean age 59 ± 13 years) were included. Analysis was performed using a commercially available system with high-pass filters of 25, 40, and 80 Hz without any change in electrode position. The following time-domain parameters were measured: (1) total filtered QRS duration; (2) duration of high-frequency low-amplitude signals (HFLA); and (3) root-mean-square voltage of the terminal 40 ms of the QRS complex (RMS40). Correlation between pairs of measurements was excellent, ranging from 0.91–0.99 for QRS and HFLA duration, and from 0.83–0.98 for RMS40 value. However, the range of differences was wide for all parameters, especially at 25 and 80 Hz, revealing marked individual variations in selected cases. The immediate reproducibility of an initially normal SAECG was 95% at 25 Hz, 100% at 40 Hz, and 81 % at 80 Hz; figures for an initially abnormal SAECG were 89%, 91 %, and 93%, respectively, and the coefficient of agreement kappa was highest at 40 Hz than at 25 or 80 Hz. Discordant results were most frequently observed in patients with borderline values, or in cases with nonsimilar residual noise levels. In conclusion, the immediate and day-to-day reproducibility of the SAECG is excellent in patients with chronic stable coronary artery disease. However, individual variations are observed in selected cases, leading to modification in interpretation of the result. For this reason, individual reproducibility should be considered before evaluating the effect of any therapeutic intervention on the SAECG, especially in patients with borderline values of the quantitative parameters of the SAECG.     

Immediate and Short-Term Reproducibility of the P Wave Signal-Averaged Electrocardiogram

While abnormalities in the P wave SAECG have been associated with the occurrence of AF, its reproducibility has never been documented. The purpose of this study was to evaluate the immediate and short-term reproducibility of measurements from the P wave SAECG. P wave SAECGs were obtained using well-described techniques that utilize the QHS complex as the trigger and the P wave as template for averaging. In 28 subjects (8 controls, 11 with cardiac disease, 9 with prior AF), 3 P wave SAECGs were obtained: an initial study; an immediate reacquisition; and reacquisition after 4–5 days. Vector duration and RMS voltage of the terminal 20 ms of the P wave SAECG were measured and compared. The mean P wave duration was 152 ± 14 ms on initial SAECG, 152 ± 14 ms and 152 ± 15 ms at immediate and short-term reacquisitions, respectively (both P = NS vs initial). The mean terminal BMS voltage was 6.4 ± 6.0 mcV on initial SAECG, 6.4 ± 5.9 mcV and 6.5 ± 5.8 meV at immediate and short-term reacquisitions, respectively (both P = NS vs initial). Linear regression analysis showed high reproducibility for both P wave duration (r = 0.94 for immediate and r = 0.96 for short-term reacquisition vs initial) but slightly less for terminal RMS voltage (r = 0.92 for immediate and r = 0.84 for short-term reacquisition vs initial). In subgroup analysis, P wave duration measurements were highly reproducible in controls, in subjects with cardiac disease, and in those with a history of AF. P wave duration was also reproducible for both males and females, as well as for subjects age > 65 years (r = 0.96 and 0.89 for immediate and short-term reacquisition, respectively). Terminal RMS voltage measurements were reproducible for controls, but less reproducible in other subgroups. In conclusion, P wave duration measurements on SAEGG are reproducible when evaluated at immediate and short-term reacquisition regardless of age, sex, cardiac disease, or prior AF. Terminal RMS voltages were less reproducible, especially in patients with cardiac disease and/or prior AF. These findings may explain conflicting observations regarding the clinical utility of terminal P wave measurements.     

Signal-Averaged P Wave in Patients with Paroxysmal Atrial Fibrillation

The theoretical and experimental rational of atrial signal-averaged ECG in patients with AF is delay in the intra-atrial and interatrial conduction. Similar to the ventricuiar signal-averaged ECG, the atrial signai-averaged ECG is an averaging of a high number of consecutive P waves that match the template created earlier. P wave triggering is preferred over QRS triggering because of more accurate aligning. However, the small amplitude of the atrial ECG and its gradual increase from the isoelectric line may create difficulties in defining the start point if P wave triggering is used. Studies using P wave triggering and those using QRS triggering demonstrate a prolonged P wave duration in patients with paroxysmal AE. The negative predictive value of this test is relatively high at 60%–80%. The positive predictive value of atrial signal-averaged ECGs in predicting the risk of AF is considerably lower than the negative predictive value. All the data accumulated prospectively on the predictive value of P wave signal-averaging was determined only in patients undergoing coronary bypass surgery or following MI; its value in other patients with paroxysmal AF is still not determined. The clinical role of frequency-domain analysis (alone or added to time-domain analysis) remains undefined. Because of this limited knowledge on the predictive value of P wave signal-averaging, it is still not clinical medicine, and further research is needed before atrial signal-averaged ECG will be part of clinical testing.     

Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting?

VASSILIKOS V., et al. : Can P Wave Wavelet Analysis Predict Atrial Fibrillation After Coronary Artery Bypass Grafting? The purpose of this study was the evaluation of Morlet wavelet analysis of the P wave as a means of predicting the development of atrial fibrillation (AF) in patients who undergo coronary artery bypass grafting (CABG). The P wave was analyzed using the Morlet wavelet in 50 patients who underwent successful CABG. Group A consisted of 17 patients, 12 men and 5 women, of mean age   66.9 ± 5.9 years   , who developed AF postoperatively. Group B consisted of 33 patients, 29 men and 4 women, mean age   62.4 ± 7.8 years   , who remained arrhythmia-free. Using custom-designed software, P wave duration and wavelet parameters expressing the mean and maximum energy of the P wave were calculated from 3-channel digital recordings derived from orthogonal ECG leads (X, Y, and Z), and the vector magnitude (VM) was determined in each of 3 frequency bands (200–160 Hz, 150–100 Hz and 90–50 Hz). Univariate logistic-regression analysis identified a history of hypertension, the mean and maximum energies in all frequency bands along the Z axis, the mean and maximum energies (expressed by the VM) in the 200–160 Hz frequency band, and the mean energy in the 150–100 Hz frequency band along the Y axis as predictors for post-CABG AF. Multivariate analysis identified hypertension, ejection fraction, and the maximum energies in the 90–50 Hz frequency band along the Z and composite-vector axes as independent predictors. This multivariate model had a sensitivity of 91% and a specificity of 65%. We conclude that the Morlet wavelet analysis of the P wave is a very sensitive method of identifying patients who are likely to develop AF after CABG. The occurrence of post-CABG AF can be explained by a different activation pattern along the Z axis. (PACE 2003; 26[Pt. II]:305–309)     

P波离散度、QT离散度和ST-T对冠心病的诊断价值

目的　探讨P波离散度 (Pd)、QT离散度 (QTd)和ST T段综合分析 ( 2 + 1方法 )对诊断冠心病的价值。方法　分析 3 5例经冠脉造影证实的冠心病患者Pd、QTd和ST T ,以 19例临床疑有冠心病 ,但经冠脉造影证实冠脉正常的健康者为对照。结果　Pd和QTd冠心病组均高于对照组 (P <0 .0 1) ,分别为 ( 2 4.15± 10 .13 )ms、( 45 .2 7±18.96)ms和 ( 15 .76± 9.68)ms、( 2 9.69± 7.74)ms。对冠心病的诊断 ,2 + 1方法的敏感性和特异性分别为 71.4%和73 .7% ,而单纯ST T分析的为 97.1%和 47.3 % ,两者间差异显著 (P <0 .0 1)。结论　与观察ST T变化比 ,Pd、QTd和ST T综合分析是诊断冠心病较特异的指标     

Characteristics of the Signal-Averaged P Wave in Orthotopic Heart Transplant Recipients

Rejection remains the Achilles heel of Orthotopic cardiac transplantation (OHT). Reliable non-invasive markers of rejection are desirable for timely therapy and to reduce risks and costs. Changes in atrial electrophysiology may precede ventricular changes during acute rejection. Although P wave duration in the signal-averaged ECG reflects atrial conduction, the feasibility of such measurement and the range of its values in OHT patients in absence of rejection is uncertain. This study compared the filtered P wave duration in 15 hypertensive OHT patients free of rejection with that in 15 age-matched hypertensive controls. All OHT patients had biatrial anastomoses. Two electrophysiologists interpreted the tracings independently. Three tracings (2 OHT, 1 control) could not be interpreted by either reader. An adequate P wave signal-averaged ECG was obtained in the remaining patients, despite the frequent presence of dissociated P waves (recipient and donor atria) on standard ECG in OHT patients. There was good interobserver agreement in the measurement of filtered P wave duration (r = 0.91; P < 0.0001). Conclusions: The filtered P wave duration was significantly shorter in the OHT patients (112 ± 15 ms versus 128 ±14 ms; P= 0.008). Filtered P wave duration can be measured in most OHT. Filtered P wave duration is shorter in OHT patients than in hypertensive controls, possibly as a result of the reduced mass of the truncated donor atria. Further studies are needed to determine whether the signal-averaged P wave can be useful to predict acute cardiac rejection.     

Analysis of the P Wave in the Signal-Averaged Electrocardiogram: Normal Values and Reproducibility

To apply p wave analysis of the signal-averaged electrocardiogram (SAECG) clinically, the knowledge of normal values and the verification of highly reproducible measurements are essential. In 40 healthy volunteers (ages 23 -37 years), an SAECG of the p wave was performed and then repeated after 1 week and 1 month. In addition to Simson analysis (unidirectional and bidirectional filters), the data were filtered with finite impulse response (FIR) and least squares fit (LSQ) filters to obtain a better differentiation between the end of the p wave and QRS onset. All recordings were evaluated by two independent observers, and the following parameters were calculated: the duration of the p wave in the three unfiltered leads; and for the vector magnitude of the three leads x, y, and z: the duration of the p wave and the root mean square voltage of its last 30, 20, and 10 ms. The average p wave duration was significantly different among the various filter techniques: 135 ± 7 ms (unidirectional); 97 ± 8 ms (bidirectional); 109 ± 8.5 ms (FIR); and 126 ± 10 ms (LSQ) (P = 0.001 for each comparison). There was a good reproducibility of the data analyzed with the Simson method (R = 0.80–0.91). Filtering with the FIR and LSQ leads to a considerably greater variability.     

血清腹脂素的表达水平与冠心病及其危险因素的关系

目的：通过检测冠心病患者的血清腹脂素水平和其他危险因素,探讨血清腹脂素与冠心病及其危险因素的相关性。方法：129例在我院行冠状动脉造影患者,根据造影结果分为冠心病组（96例）和对照组（33例）,冠心病组根据患者症状、心电图、心肌酶谱进一步分为急性ST段抬高型心肌梗死组27例（STEMI组）及不稳定型心绞痛/非ST段抬高型心肌梗死组32例（UA/NSTEMI组）,稳定性心绞痛组37例（SAP组）。测定各组患者血清腹脂素水平,同时检测血清总胆固醇、三酰甘油、高密度脂蛋白、低密度脂蛋白、载脂蛋白A、载脂蛋白B100、脂蛋白（a）、空腹血糖、肌酐水平。结果：在冠心病各组中腹脂素水平STEMI组〉UA/NSTEMI组〉SAP组〉对照组（26.96±5.30ng.dL-1比24.20±6.88ng.dL-1比20.84±4.63ng.dL-1比19.85±8.08ng.dL-1）。其中STEMI组和UA/NSTEMI组腹脂素水平显著高于对照组（P〈0.01）和SAP组（P〈0.05）。相关分析显示血清腹脂素水平与空腹血糖相关,与冠心病其他危险因素不相关。Logistic逐步回归分析显示血清腹脂素水平升高与冠心病独立相关。结论：血清腹脂素水平升高与冠心病独立相关。     

Comparison of Spectral Temporal Mapping to the Time Domain Signal-Averaged Electrocardiogram in Normal Subjects and in Patients with Coronary Artery Disease and Sustained Ventricular Tachycardia

Spectral temporal mapping is a new form of analysis for signal-averaged electro-cardiography, which has the goal of improving the sensitivity and specificity of traditional time domain analysis. Our objective in this study was to determine the effectiveness of one form of spectral temporal mapping, in the face of conflicting results that have so far been reported with this approach. We prospec-tively performed both spectral temporal mapping and time domain analysis on 50 patients with a history of coronary artery disease and inducible sustained monomorphic ventricular tachycardia (Group 1) and on 25 normal subjects with normal electrocardiograms and no history of heart disease (Group 2). We found that for the 40 Group 1 patients without bundle branch block (Group lA), the sensitivity of spectral temporal mapping was lower than that for time domain analysis (45% vs 80%, P < 0.005). The results of spectral temporal mapping for Group lA patients were similar to that for all of Group 1. The sensitivity of spectral temporal mapping was 60% (n = 10) for patients with bundle branch block (Group IB). The specificity noted in Group 2 was 88% by each means of analysis; however, no one In Group 2 had an abnormal finding by time domain and spectral temporal mapping. Attempts to optimize the criteria for an abnormal spectral analysis did not identify criteria that were superior to those currently in use. We conclude that spectral temporal mapping using Haberl's method is inferior to time domain analysis in identifying patients with sustained ventricular tachycardia, but may be of value in conjunction with the traditional approach in identifying normal subjects.     

Colchicine in Stable Coronary Artery Disease

Purpose

Disease management of stable coronary artery disease consists of controlling hemostasis and lipid regulation. No treatment strategies preventing plaque erosion or rupture are yet available. Cholesterol crystal–induced inflammation leading to plaque destabilization is believed to be an important factor contributing to plaque instability and might well be amenable to treatment with anti-inflammatory drugs. Colchicine has anti-inflammatory properties with the potential to address both the direct and indirect inflammatory mechanisms in the plaque.

Anticoagulant Therapy in Coronary Artery Disease

The “when, why and how” to use anticoagulants in coronary disease is still controversial. In these statements two internationally known authorities express their views. It is challenging to read their opinions.     

Common Problems in Coronary Artery Disease

Plethora in one of a pair of monozygotic twins and pallor in the other are now understood as evidence of intrauterine transfer of blood by way of vascular anastomoses in the placenta. The artery-to-vein type of communication acts as an arteriovenous shunt. The syndrome is an important cause of fetal and neonatal morbidity and mortality.     

餐后2小时血糖水平结合外周动脉脉搏波传导速度对冠脉病变的预测价值

目的探讨患者餐后2小时血糖水平结合外周动脉脉搏波传导速度对冠心病的预测价值,为以无创方法早期检出冠脉病变患者提供依据。方法选取2007年7～11月拟诊冠心病的患者158例,分别测量餐后2小时血糖值和外周动脉脉搏波传导速度,并进行冠状动脉造影,评价餐后2小时血糖值结合外周动脉脉搏波传导速度对冠心病的诊断价值。结果餐后2小时血糖值升高对诊断冠状动脉病变的敏感性为65.04%,特异性为51.43%;而外周动脉脉搏波传导速度增快对诊断冠状动脉病变的敏感性为67.48%,特异性为42.86%;二者结合对诊断冠状动脉病变的敏感性为82.14%,特异性为83.33%,显著高于单独两种检测方法(P<0.05)。结论餐后2小时血糖水平结合外周动脉脉搏波传导速度对冠心病有较好的预测价值。     

高频超声探查颈动脉预测冠状动脉病变

目的以颈动脉为窗口，探讨颈动脉与冠状动脉硬化间关系。方法用高频超声探查冠状动脉多支病变组，一支病变组与对照组的颈动脉内中膜厚度值(IMT)，斑块分级。结果三组IMT值及斑块分级存在显著差异。以斑块存在为预测冠脉病变的阳性指标，敏感性为83％，持异性为77％。1ogistic回归分析发现斑块为预测冠状动脉粥样硬化性。0脏病(CAHD)的最有效的阳性指标。结论高频超声探查颈动脉可预测冠状动脉病变的存在及严重程度。     

高血压合并冠心病患者的冠脉病变特点

目的 探讨高血压合并冠心病患者的血压及冠脉病变特点.方法 对358例高血压合并冠心病患者和144例单纯冠心病患者进行24h动态血压监测,分析动态血压参数.两组患者都行冠脉造影术,冠脉病变程度以病变的血管支数表示.结果 高血压合并冠心病组患者血管狭窄程度重,弥漫性血管病变多见,且明显高于单纯冠心病组患者(x2＝6.03,P＝0.019);其中复杂病变患者24h动态收缩压、日间动态收缩压、夜间动态收缩压、24h 动态脉压、日间动态脉压、夜间动态脉压都高于简单病变组(t值分别为2.580、2.045、2.675、2.037、2.601、1.995;P 值分别为0.015、0.037、0.009、0.041、0.017、0.047).结论 与单纯冠心病患者相比,高血压合并冠心病患者的冠状动脉的病变程度更重,故应对血压进行良好的控制以减轻高血压合并冠心病患者冠脉病变的程度.     

Prevalence and Significance of Obstructive Coronary Artery Disease in Patients with Zero Coronary Artery Calcium Score

Abundant data have established coronary artery calcium score (CACS) in the algorithm of cardiovascular risk stratification, especially for those at intermediate risk of coronary artery disease (CAD). Absence of CACS is associated with a very low cardiac event rate in asymptomatic individuals and no further imaging is required. Cardiac event rates in symptomatic patients are comparatively higher but still relatively low and have to be interpreted in the context of the population included. Conflicting results from angiography literature with a reported presence of obstructive CAD in up to 39% of mostly symptomatic patients with zero CACS are explained by the higher-risk patients enrolled. CACS is an excellent test for asymptomatic patients in predicting cardiac events and absence of obstructive CAD but has a limited role in symptomatic and higher-risk patients encountered by a cardiovascular specialist, particularly those referred for CT angiography and invasive coronary angiography. This is especially true for relatively young patients (<45 years of age).     

心率变异性对变异性心绞痛患者冠脉病变的评估价值

【目的】探讨心率变异性（HRV）对变异性心绞痛患者冠脉病变的评估价值。【方法】回顾性分析本院2011年1月至2014年12月收治的96例变异性心绞痛患者,根据冠脉造影结果进行分组,冠状动脉直径减少≥50％为有意义病变组,冠状动脉直径减少＜50％为无意义病变组;有意义病变组中显示为左回旋支、左前降支、右冠状动脉有一支病变则为单支病变组,左回旋支、左前降支、右冠状动脉有两支或两支以上病变或单纯左主干病变则为多支病变组。单支病变组中冠脉狭窄≥75％为重度狭窄组,冠脉狭窄50％～75％为轻中度狭窄组。【结果】有意义病变组 H RV指标均低于无意义病变组,差异具有统计学意义（ P ＜0．05）;多支病变组H RV指标均低于单支病变组,差异具有统计学意义（ P ＜0．05）;重度狭窄组 H RV指标均低于轻中度狭窄组,差异具有统计学意义（ P ＜0．05）。【结论】通过对变异性心绞痛患者进行 HRV分析,可以了解冠状动脉病变程度,对评估病情和诊治变异性心绞痛有重要意义。