bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidence and Clinical Significance of Ventricular Late Potentials in Idiopathic Dilated Cardiomyopathy Compared to Coronary Artery Disease
Authors: Grimm Wolfram , Winzenburg Jens , Knop Ursula , Hoffmann Jürgen , Menz Volker , Grote Frank , Maisch Bernhard
Published: October 2006

Objective: This prospective study was designed to compare incidence and clinical significance of ventricular late potentials between patients with idiopathic dilated cardiomyopathy (IDC) and postinfarct patients (CAD) using exactly the same method of signal‐averaged electrocardiography (SAECG) in both patient groups.

Methods: Time‐domain analysis of SAECG was performed in 120 consecutive patients with IDC, 120 patients with CAD, and 60 healthy controls. Ventricular late potentials were detected in 27 of 120 patients with IDC (23%) compared to 41 of 120 patients with CAD (34%; P < 0.05).

Results: Ventricular late potentials were found in 2 of 60 controls (3%). During 15 ± 7 months follow‐up, serious arrhythmic events occurred in 17 of 120 patients with IDC (14%) and in 13 of 120 patients with CAD (11%). The sensitivity of ventricular late potentials for future arrhythmic events was 35% for IDC compared to 77% for CAD (P < 0.05). The positive predictive value of late potentials detected by time‐domain analysis was 22% for IDC versus 24% for CAD (P = ns).

Conclusion: In this selected patient population with IDC and CAD, time‐domain analysis of SAECG revealed a lower incidence of ventricular ate potentials in patients with IDC as compared to postinfarct patients. Whereas ventricular late potentials had a high sensitivity but a low positive predictive value for identification of postinfarct patients with serious arrhythmic events during follow‐up, both sensitivity and positive predictive value of ventricular late potentials for future serious arrhythmic events were low in the setting of IDC.
Development of a New Device for Diagnosis of Hypoxemia and Arrhythmia by SaO2 ECG Holter Monitoring
Authors: Nakamoto Takaaki , Momoki Shigeru , Harasawa Hiroshi , Ohnuma Noboru , Kato Shiro , Hase Tatsuya , Kuga Hideyo , Kishiro Izumi , Ohno Kunihiko , Suzuki Hidehiko , Tokoyama Kouki , Okamoto Shingo , Takasaki Keiji , Saitoh Koh‐ichi , Tamamura Kazuki , Abe Tetsuro , Iizuka Masahiko
Published: October 2006

Background: We have developed a system to monitor, simultaneously and continuously, ambulatory SaO2 measured using a pulse‐oximeter and ECG data for 24 hours.

Methods: The ambulatory SaO2‐ECG monitoring system consisted of a portable monitoring device (SM50) with two channels for ECG data and one channel for SaO2 data input; a sensor for SaO2 recording; and a pulse‐oximeter. An ambulatory monitoring analyzer was used. The SaO2 report from the present analyzer included two types of data (i.e., a profile of heart rate [HR], pulse rate [PR], and SaO2 value per min), and a trend graph of HR, arrhythmia, ST level and slope, PR, and SaO2 per minute. We also designed and produced an analytical program to automatically remove noise errors relating to the SaO2 measurement.

Results: Using this system, we performed a clinical study on ten healthy volunteers (Group N) and seven patients with chronic pulmonary diseases (Group CPD) to evaluate the usefulness of the system as a diagnostic means for respiratory failure and arrhythmia. Group N showed a stable value of 90% or over in SaO2 during the 24‐hour monitoring while Group CPD showed values under 90% SaO2 in all patients at rest during the night or after a 15‐minute walk. Transient atrial tachycardia (TAT) was observed in 3 of 7 CPD patients, and each episode was preceded by a decrease of SaO2. The occurrence of a single or double ventricular extrasystole was high in Group CPD compared with Group N (1.21 ± 0.89 vs 0.6%± 0.3%, P < 0.05), its occurrence was not associated with a decrease in SaO2.

Conclusions: In outpatients, especially patients who are taken care of at home, the present system will certainly contribute greatly to the diagnosis of respiratory failure and arrhythmia as well as to evaluate the effects on these diseases of therapy. In addition it is suggested that in CPD, patients’hypoxemia may induce TAT.
ECG Diagnosis of Coronary Artery Disease
Authors: Frogner Fredrik J. , Juul‐Möller Steen
Published: October 2006

Objective: In order to assess the diagnostic accuracy of ST depression in the diagnosis of coronary artery disease (CAD) in patients with suspected myocardial ischemia we compared ST depression in 3‐lead ambulatory ECG (AECG) with that of exercise tolerance testing (ETT).

Methods: Significant coronary artery stenosis in coronary angiography was used as a standard reference. ST analysis could be performed in 106 of the investigated 113 patients, all with suspected CAD. One person with left bundle branch block was excluded from the ST analysis, and six persons could not perform ETT.

Results: Seventy‐eight of the 106 patients had at least one significant stenosis (> 70% narrowing) and 28 had no stenosis according to coronary angiography. The sensitivity for AECG was 62% and for ETT it was 63%, the specificity for AECG was 79% and for ETT the specificity was 57%. The accuracy for AECG was 66%, and for ETT it was 61%. We also evaluated late potentials (LPs) from the AECG tapes in order to correlate LP to left ventricular function (LVF), myocardial infarction (Ml), and/or CAD. We found that LP correlates better to advanced CAD than to Ml or LVF.

Conclusion: The accuracy of ST diagnosis of CAD in patients with suspected myocardial ischemia using AECG was equal to that of a maximal ETT. LP finding from an AECG tape may support the argument for CAD in patients with ST depressions at AECG.
The Correlation Dimension of Heart Rate Variability Reflects Cardiac Autonomic Activity
Authors: Kamen Peter Walter , Krum Henry , Tonkin Andrew Maxwell
Published: October 2006

Background: Linear methods of time series analysis such as summary statistics and frequency‐domain parameters have been used to measure heart rate variability (HRV). More recently, nonlinear methods including the correlation dimension (CDim) have been used to evaluate HRV. The aim of this study was to examine the effect of autonomic perturbations on the CDim.

Methods: The CDim was calculated from 2000 data points (RR intervals) collected over a relatively short period of time (20–40 min) in 12 healthy subjects aged between 20 and 40 years (mean 30 ± 2 years) during: (a) supine rest; (b) head up tilt (sympathetic activation, parasympathetic nervous system activity withdrawal); (c) intravenous infusion of atropine (parasympathetic nervous system activity withdrawal); and (d) following overnight administration of low dose transdermal scopolamine (parasympathetic nervous system augmentation.

Results: The CDim was determined at rest (7.8 ± 0.3) and found to be significantly reduced during tilt (5.9 ± 0.4, P < 0.01) and atropine administration (4.2 ± 0.4, P < 0.01) and possibly increased by scopolamine (8.3 ± 0.5, NS).

Conclusions: The changes following these interventions suggest that CDim can accurately measure cardiac autonomic nervous system activity.
QRST Isointegral Map in Dilated Cardiomyopathy
Authors: Kawakami Yoshihide , Sakai Yasuhiko , Shimada Satoshi , Nagao Hikaru , Hirota Yuzo , Kawamura Keishiro
Published: October 2006

Objective: To investigate the clinical significance of the QRST isointegral map in patients with dilated cardiomyopathy (DCM).

Methods: We performed body surface mapping, signal‐averaged ECG, and 201TI myocardial imaging in 41 patients with DCM. Using the QRST I‐sub map, we derived the two parameters of the number of lead points below −2 standards of deviation for the normal nSub value and the absolute value of the Dimin.

Results: LPs were detected in 17 patients (41%). The QRST I‐sub map disclosed an abnormal negative area in most of the 41 patients. Both nSub and Dlmin values were larger in the group with LP than in the other group (P < 0.01). Significant inverse correlation was detected between the root mean square voltage in the last 40 ms (index of LP) and the Dlmin value (r =−0.435, P < 0.001). The abnormal scintigraphic patterns were classified into three groups with decreased uptake in the anteroseptal, inferoapical, and postero‐lateral regions, the localizations of which were well‐matched to the minimal points on the QRST I‐sub map (F‐G 4, G‐H 2, and I‐J 3–4, respectively). There was also a close correlation between the myocardial perfusion abnormalities and the distribution of the −2SD area on the QRST I‐sub map.

Conclusion: The QRST isointegral map is useful in detecting the extent and localization of the myocardial damage in patients with DCM.
Predictive Value of Late Potentials after Myocardial Infarction in the Thrombolytic Era
Authors: Bruna Claudio , Vado Antonello , Rossetti Guido , Racca Emanuela , Ferrero Valeria , Cherasco Elvira , Fantino Ivana , Isoardi Daniela , Uslenghi Eugenio
Published: October 2006

Background: The value of the signal‐averaged electrocardiogram (ECG) for prediction of arrhythmic events (AE) after myocardial infarction (MI) has been well established. The current incidence of AE in the first year after Ml is remarkably lower than that reported in the 1980s. In this study, we compared the prevalence and the predictive value of late potentials (LP) in patients with Ml treated with either conventional or reperfusion therapy.

Methods: A total of 433 patients (age 62 ± 10 years, 350 men) recovering from acute Ml were prospectively analyzed. Two hundred seven patients had conventional therapy (group A), and 226 had reperfusion therapy (group B) within 12 hours of the onset of symptoms: 145 of group B patients received thrombolytic agents, whereas 81 underwent direct or rescue angioplasty. Standard signal‐averaged variables were recorded (filter range 40–250 Hz) 10 ± 6 days (range 5–30 days) after Ml. LP were defined as being present if 2 of the following were met: fQRS <114 ms, RMS40 20 μV, LAS40 <38 ms (criterion 1), and if QRS 120 ms (criterion 2).

Results: LP were found in 33% versus 21%, P = 0.004 (criterion 1) and in 13% versus 8%, P = 0.057 (criterion 2) of group A and group B patients, respectively. During a mean follow‐up of 24 ± 19 months (range 5 days to 48 months), there were 22 AE (5%). The AE rate for patients with conventional therapy was significantly higher in those with LP than in those without LP: 12% versus 4%; P = 0.03 (criterion 1) and 30% versus 3%; P = 0.00003 (criterion 2). The AE rate for patients with reperfusion therapy was similar in patients with and without LP: 9% versus 3%, P = 0.09 (criterion 1) and 12% versus 3%, P = 0.14 (criterion 2). Multivariate analysis indicated that the presence of LP based on criterion 2 was the strongest independent predictor of AE in patients with Ml treated with conventional therapy.

Conclusion: In this study, reperfusion therapy influenced the prevalence of LP. The predictive value of LP for serious AE in the postinfarction period was remarkably affected by thrombolysis and/or interventional catheter therapy.
QT Dynamics from Holter Recordings: A Comparison of Two Averaging Methods
Authors: Kluge Petra , Rose Ekkehard , Meyer Claudia , Wittig Kathrin , Walter Thomas , Neugebauer Annerose , Pfeiffer Dietrich
Published: October 2006

Background: QT dynamics is the adaptation of repolarization duration on heart rate. There are several automatic computer algorithms for Holter analysis to describe this process. Our study was performed to compare results of two averaging algorithms inherent in an automatic Holter QT module.

Methods: Two different methods of the automatic QT module of the ELATEC system were applied to digitized Holter ECGs of 50 healthy men. The first method, “QT/RR,” calculates the linear regression up to 2880 mean QT intervals (values over 30 s) and corresponding RR intervals containing the preceding 60 seconds of the QT value and the 30 seconds while QT averaging. The second method, “QT/RR class,” correlates the averaged QT duration over the corresponding 25‐ms RR interval classes. Possible differences in rate adaptive behavior between two portions of QT duration were of further interest.

Results: The main result of the study was that the linear regression obtained by the “QT/RR” method was slightly, but significantly, steeper than those obtained by the “QT/RR class” method.

Conclusion: Rate adaptation of QTe and QTa is the same if measured by one particular method. Studying the same population using different averaging methods leads to different results. In contrast to the “QT/RR” method, “QT/RR class” method leads to an overestimation of extreme and rare RR values. Therefore, results of “QT/RR class” method cannot be used as a surrogate for “QT/RR” methods.
Change of QT Dispersion After PTCA in Angina Patients
Authors: Choi Kee‐Joon , Lee Cheol‐Whan , Kang Duk‐Hyun , Song Jae‐Kwan , Kim Jae‐Joong , Park Seong‐Wook , Park Seung‐Jung , Park Chong‐Hun , Kim You‐Ho
Published: October 2006

Background

QT dispersion (QTd) represents the inhomogeneity of ventricular repolarization and has been reported to predict ventricular tachyarrhythmias in postmyocardial infarction patients. This study investigates the short‐term effect of percutaneous transluminal coronary angioplasty (PTCA) on QTd in patients with coronary artery disease (CAD) and no history of previous myocardial infarction.

Methods

In 84 angina patients (65 men and 19 women, mean age, 58.3 ± 9.0 years) who underwent successful PTCA of a single coronary artery, ECG was recorded in baseline, immediate, 1 day, and 1 month after PTCA for measurement of QTd and corrected QTd (c‐QTd).

Results

PTCA was performed at the left anterior descending artery (LAD) in 56, left circumflex artery (LCx) in 12, and right coronary artery (RCA) in 16 patients. QTd (c‐QTd) at baseline, immediately, 1 day, and 1 month following PTCA was 51.3 ± 4.2 (50.7 ± 4.1), 54.2 ± 4.5 (52.8 ± 4.5), 47.7 ± 4.3 (48.5 ± 4.8), and 36.3 ± 4.5 (37.5 ± 4.6) ms, respectively. QTd and c‐QTd significantly decreased at 1 month following PTCA. The difference was more prominent in patients with LAD lesion than LCx or RCA lesion, independent of gender, severity of stenosis, and use of beta‐blocker.

Conclusions

QTd decreases in CAD patients with no history of myocardial infarction at 1 month following successful PTCA. This suggests that PTCA facilitates a favorable recovery from inhomogeneous repolarization due to myocardial ischemia. This finding calls for long‐term follow‐up of QTd and risk of ventricular tachyarrhythmias and sudden death following successful PTCA.
Abnormal QT Dispersion Predicts Unexpected Sudden Death in Young Patients with Thalassemia Major
Authors: Cuomo Sergio , Mayer Maria C. , Comoletti Carmela , D'Onofrio Antonio , Buffardi Salvatore , Russo Vittorio
Published: October 2006

Background:QT interval dispersion has been proposed as a simple noninvasive predictor of ventricular arrhythmias and sudden death. Patients with thalassemia major are at increased risk for sudden death. However, the independent effect of increased QT dispersion on the risk of sudden death in thalassemia major is not known. This study sought to test the hypothesis that an abnormal QT dispersion predicts sudden death in patients with thalassemia major.

Methods:QT dispersion was measured in 13 consecutive patients with thalassemia major who had sudden death at a mean age of 16.1 ± 2.8 years, and in 13 survivors matched for age, gender, examination year, and transfusion therapy.

Results:Patients who died suddenly had significantly greater QT dispersion (59 ± 29 ms) than patients who survived (29 ± 13 ms; P = 0.002). A cut‐off value of 50 ms for QT dispersion had a sensitivity of 54%, a specificity of 92%, a positive predictive value of 87%, a negative predictive value of 67% and a predictive accuracy of 73% in identifying patients at risk of sudden death. With multiple regression analysis, QT dispersion was the only independent predictor of sudden death.

Conclusions:QT dispersion is a useful marker of risk of sudden death in patients with thalassemia major. A.N.E. 1999;4(3):295–300
Determinants of Efficacy of Beta‐Blocker Therapy in Patients with Asystole Induced During Head‐up Tilt Testing
Authors: Kouakam Claude , Lacroix Dominique , Vaksmann Guy , Klug Didier , Jarwe Moustapha , Mairesse Georges , Key Christian , Kacet Salem
Published: October 2006

Background:The prognosis and treatment of patients with prolonged asystole during head‐up tilt test (HUT) remain controversial. The aim of this study was to identify factors predicting a favorable outcome in patients with unexplained syncope who have an asystolic response during HUT.

Methods:Passive HUT was performed at 60° for up to 45 minutes in 329 patients (162 women and 167 men, mean age 38 ± 22 years). Isoproterenol was given in escalating doses when passive HUT was negative. Asystole was defined as a ventricular pause 5 seconds.

Results:Among the 173 patients with positive HUT, 21 developed syncope related to asystole (mean duration 13 ± 7.5 seconds). According to our initial experience, beta‐blocker therapy was used as a first line treatment. At repeat HUT on beta blockers, 16 patients (group I) were partially (n=5) or totally (n=11) controlled by beta blockers, as opposed to 5 patients (group II) in whom asystole remained inducible. Three of them required implantation of a pacemaker and the two others refused. When compared to group I patients, group II patients were older (50 ± 9 vs 24 ± 10 years, P < 0.001) and had a longer asystole duration (22 ± 7 vs 10 ± 5 seconds, P < 0.005) during initial HUT, while spontaneous clinical manifestations were identical. The diagnostic accuracy to predict failure of beta blockers was 83% for age > 40 years, 80% for asystole > 15 seconds and 100% for both. After a follow‐up of 35 ± 11 months, the two patients of group II who refused pacemaker, experienced recurrence of syncope, while the three others remained free of symptoms. Concerning group I, patients successfully managed were asymptomatic, and few episodes of recurrent presyncope were observed in only four of those partially controlled by beta blockers.

Conclusions: Prolonged asystole (> 15 seconds) and an older age (> 40 years) both predict a poor response to beta‐blocker therapy in patients with vasovagal syncope referred to as malignant. Satisfactory HUT under beta blockers predict a favorable clinical outcome. A.N.E. 1999;4(4):377–384
Adequacy of an Exercise Test in Excluding Angina on Patients Presenting to the Emergency Department with Chest Pain
Authors: Senaratne Manohara P.J. , Carter Debbie , Irwin Marleen
Published: October 2006

Background:The clinical utility and cost effectiveness of exercise testing (ET) following evaluation by a cardiologist to exclude angina in patients presenting to the emergency department (ED) with chest pain was evaluated.

Methods:Patients presenting to the ED with no apparent cause were evaluated. Of 239 patients presenting to the ED with chest pain without a history of coronary artery disease, 23 underwent sestamibi scanning with 216 undergoing ET. Follow‐up evaluation was performed by telephone.

Results:Of 216 ETs, 168 (77.8%) were negative, 24 (11.1%) positive, 24 (11.1%) indeterminate (209 discharged home directly). During follow‐up (mean 20 months: range 5–37) there were three noncardiac deaths (malignancies = two, pneumonia = one) with five patients diagnosed with angina among the 168 with negative tests. Forty‐two patients indicated unscheduled return visits (ED = 15, physician's office = 23, admissions = 4). The present management strategy realized a saving of Canadian (Cdn). $86,585.60 when compared with sestamibi scanning as the primary test.

Conclusions: ET following an evaluation by a cardiologist can be used for the initial screening of patients presenting with chest pain to the ED with a high negative predictive accuracy with regard to future coronary events. Nuclear perfusion imaging can be used in a minority of patients where an ET is not feasible. A.N.E. 1999;4(4):408–415
Correlation Method for Detection of Transient T‐Wave Alternans in Digital Holter ECG Recordings
Authors: Burattini Laura , Zareba Wojciech , Moss Arthur J.
Published: October 2006

Background:Spectral and complex demodulation methods for detection of microvolt T‐wave alternans (TWA) have limited ability to identify transient (nonstationary) TWA episodes. We aimed to develop and test new time‐domain technique allowing TWA detection and quantification in as few as 7 consecutive beats from sinus rhythm ECGs.

Methods and results:Quantification of TWA during sinus rhythm required preprocessing consisting of: low‐pass filtering, RR stability testing, baseline and respiratory modulation removal, and T‐wave windowing and synchronization. Our time‐domain correlation method (CM) detects TWA by computing, for each consecutive T wave, an alternans correlation index based on a crosscorrelation technique. CM allows quantitative analysis of the amplitude, duration, and overall magnitude of the TWA episode. The technical performance of CM was confirmed in testing with simulated TWA of varying amplitude, duration, and noisy conditions. The clinical performance of CM was demonstrated by analyzing digital Holter recordings of 39 long QT syndrome patients compared to 36 healthy subjects. CM identified TWA in 17 (44%) patients with nonstationary TWA detected in 8.

Conclusion:Our computer algorithms consisting of ECG preprocessing and TWA quantification by the correlation method provides the opportunity to detect nonstationary and stationary TWA in sinus rhythm of digital Holter ECG recordings. A.N.E. 1999;4(4):416–424
How to Obtain and Analyze Electrocardiograms in Clinical Trials
Authors: Morganroth Joel , Silber Steven S.
Published: October 2006

Prolongation of the QTc interval on the ECG associated with reports of sudden death produced by noncardiac drugs has focused the attention of regulatory authorities on ECG findings from clinical drug development programs. During clinical testing, the nonrigorous, site‐specific, and largely uncontrolled methods for performing and analyzing ECGs that is currently practiced should now be reconsidered. Current methods may miss important cardiac electrophysiological effects of new drugs as well as produce false‐positive ECG findings that are artifactual and the result of the methods used. The use of a core ECG laboratory that has cardiovascular expertise, state‐of‐the‐art information management technologies, and ECG reading systems that are scientifically validated, quality assured, and precise can cost effectively manage a development program's entire ECG safety program. A.N.E. 1999;4(4):425–433
Localized Right Precordial QRS Prolongation as the Basic ECG Finding in Arrhythmogenic Right Ventricular Dysplasia Cardiomyopathy
Authors: Peters Stefan , Getting Bettina , Peters Heidi
Published: October 2006

Background: Since the first description of arrhythmogenic right ventricular dysplasia (ARVD) in 1977 several attempts have been made to find the ideal diagnostic technique. Localized QRS prolongation in right precordial leads gained general interest in 1993, although the definition and value of this diagnostic criterion is not well established.

Method: In different cohorts of patients (93 healthy volunteers, 84 patients with task‐force criteria of ARVD, 54 patients with dilated cardiomyopathy, and 16 patients with hypertrophic cardiomy‐opathy) QRS duration was measured in precordial leads in standard ECGs with a paper speed of 50 mm/s. Two different ECG algorithms were used to differentiate ARVD: (a) QRS duration in V1, V2, or V3 < 110 ms and (b) QRS duration in (V1 + V2 + V3)/(V4 + V5 + V6) < 1.2. The frequency of right precordial T wave inversions, incomplete and complete RBBB, and left ventricular hypertrophy was analyzed in addition.

Results: The frequency of right precordial T inversions in ARVD was moderately high (64%), the frequency of incomplete RBBB (n = 2), complete RBBB (ri = 6), and left ventricular hypertrophy (n = 1) was low. A QRS duration 2 110 ms in right precordial leads was found in 80% with an overall specificity of 89%. The ECG feature of outstanding importance was a ratio of QRS duration in (V1 + V2 + V3)/(V4 + V5 + V6) == 1.2, which was present in 97% with a specificity of 100%.

Conclusions: Localized right precordial QRS prolongation best defined as a QRS duratio ratio in (V1 + V2 + V3)/(V4 + V5 + V6) s 1.2 seems to be a sensitive and specific finding in ARVD even in cases with incomplete or complete RBBB and, at least, in one case with left ventricular hypertrophy. Other forms of cardiomyopathies with certain right ventricular involvement and a control group of healthy volunteers can be differentiated with outstanding safety.
Interlead Difference in QT Interval Rate Adaptation During Exercise in Coronary Artery Disease Patients Susceptible to Ventricular Fibrillation
Authors: Oikarinen Lasse , Toivonen Lauri , Viitasalo Matti
Published: October 2006

Background: Nonhomogeneity in ventricular repolarization predisposes to ventricular tachyarrhythmias. Rate adaptation of the QT interval parallels rate adaptation of the action potential, both of which reflect the repolarization phase in ventricular myocardium. The aim of this study was to examine in patients with coronary artery disease (CAD) the relation of interlead differences in QT interval rate‐adaptation to arrhythmia vulnerability.

Methods: We studied 29 CAD patients with a history of ventricular fibrillation (VF) not associated with acute myocardial infarction (VF group), and their 29 individually matched CAD controls without arrhythmic events (controls). Rate adaptation of the QT intervals in the 12 leads of the electrocardiogram were determined from QT intervals measured at rest and at the end of each 3 minute load step during exercise test. The relation between heart rate (HR) and QT interval (QT/HR slope) was calculated separately in each lead by the linear regression equation. The slopes of these equations were used to characterize spatial QT interval rate adaptation.

Results: The steepest QTapex/ HR slopes in any lead were (mean ±mD SD) −2.45 ± 0.63 in the VF group and ‐1.97 ± 0.45 in controls (P = 0.008), whereas the smallest slopes showed no difference (P = NS). The standard deviations of QTapex/ HR slopes were 0.48 ± 0.23 in the VF group and 0.33 ± 0.12 in controls (P = 0.012).

Conclusions: Rate adaptation of the QTapex interval is locally exaggerated, resulting in nonhomogenous exercise response of the QTapex intervals in CAD patients susceptible to life‐threatening ventricular arrhythmias. A.N.E. 2000;5(4):346–353
Ethnic (Black‐White) Contrasts in 24‐Hour Heart Rate Variability in Male Adolescents with High and Low Blood Pressure: The Bogalusa Heart Study
Authors: Urbina Elaine M. , Bao Weihang , Pickoff Arthur S. , Berenson Gerald S.
Published: October 2006

Background: Heart rate variability (HRV) has been used to study autonomic effects on the heart. The time‐domain measure RMSSD (root mean square of successive differences) represents high frequency (HF) changes in HRV reflecting parasympathetic nervous system activity (PS). The frequency‐domain ratio of low to high power (LF/HF) represents sympathetic (SYMP) to PS balance. In adults, increased SYMP tone has been found in hypertensive as compared to normals. The present study was performed to look for differences in HRV by race and between young subjects with high and low levels of diastolic blood pressure (DBP).

Methods: Subjects included 34 healthy males age 13–17 years (53% white). Half were selected with K4 DBP < 85th% for height (HT) measured twice, 3–5 years apart. Half had DBP < 15th% for HT. Subjects underwent a physical examination including BP, HT, WT, and ECG prior to Holter monitor application. HRV data was analyzed from 24‐hour Holter recordings obtained during normal activity.

Results: The RMSSD was lower in whites compared to blacks for day, night, and 24‐hour average (P ≥ 0.05) with day‐time measurements showing the largest racial difference. This suggests increased PS tone in blacks especially with activity. The LF/HF ratio was higher in whites for all times, reaching significance during the day (all P ≥ 0.05) suggesting SYMP predominance in whites during activity. Subjects with higher levels of DBP had lower RMSSD and higher LF/HF ratio for all times, but these did not reach statistical significance.

Conclusions: There is a trend towards SYMP predominance in children with higher DBP. Healthy white adolescents exhibit increased SYMP tone compared to blacks when measured during normal daytime activity.
Spatial Properties of QT and the T‐Wave Morphology
Authors: Lund Kaspar , Lund Birgit , Arildsen Hanne , Pedersen Anders Kirstein
Published: October 2006

Objective: To describe the relation between the QT interval and the T‐wave morphology.

Material and methods: Frank orthogonal leads X, Y, Z of one subject and resting 12‐lead ECG of 40 subjects. QT was measured by the tangent method. The QT values are organized according to the anatomic orientation of the leads: I, ‐aVR, II, aVF, III, ‐aVL, ‐I, aVR, ‐II, ‐aVF, ‐III, aVL. and: V1, V2, V3, V4, V5, V6, ‐V1 ‐V2, ‐V3, ‐V4, ‐V5, ‐V6. The T‐wave amplitudes and QT were categorized according to QT into four groups with increasing mean QT.

Results: Kruskal‐Wallis nonparametric test showed that the shortest and longest QT values are measured on the T wave with the smallest amplitudes (P < 0.001). Inspection of plots of QT and T waves reveals that the shortest and longest QT values are usually measured in leads with a small difference in orientation (neighbor leads). The mechanism behind these characteristics is mainly that the shortest and longest QT values are measured on T waves that are close to a lead orientation, whereas the T waves are flat or biphasic. We also observed an almost significant (P = 0.057) decrease in the T‐wave amplitude with increasing dispersion.

Conclusion: The relation between T‐wave morphology and QT in the same cardiac plane is highly organized. The shortest and longest QT values are measured on the T wave with the smallest amplitudes (P < 0.001).
Ventricular Late Potentials and Degree of Reperfusion of the Infarct‐Related Artery
Authors: Barragán Antonio , Domingez Alberto , Marrero Francisco , García Martín , Iacalzada Juán , Lara Antonio , Castro Manuel , Gonzalez Vicente , Bosa Francisco , Laynez Ignacio , de Armas Diego
Published: October 2006

Background: Patency of the infarct‐related artery is known to be a powerful determinant of the prognosis after AMI. Most studies have reported a lower incidence of late potentials from patients treated with thrombolytic agents than patients not so treated. The purpose of this study was to evaluate the use of ventricular late potentials in the first week after AM1 to differentiate patients according to the TIMI flow in the infarct‐related artery.

Material and Methods: In 106 patients with AMI, we recorded three determinations of late potentials with filters of 25, 40, and 80‐250 Hz, at 24, 72, and 144 hours after the onset of symptoms. Classification was based on the angiography study: group I with TIM1 0‐1 and group I1 with TIMI 2‐3.

Results: We found a low positive predictive power in TIMI 0‐1 (around 50%) for all records and filters. The negative predictive value was high (72%‐93%) and increased with time from the AM1 and frequency of the filter. The most sensitive filter was 80‐250 Hz and the most specific was 25‐250 Hz. The duration of the QRSf and LAS40 was longer and the RAMS were lower in the patients with diminished TIMI flow.

Conclusion: The absence of late potentials is associated with a better TIMI flow in the artery.
Survey of Prophylactic Defibrillator Implantation Following MADIT
Authors: Nisam Seah , Wilber David J.
Published: October 2006

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) established an indication for implantable defibrillators (ICD) in patients with previous infarction, ejection fraction (EF) < 35%, nonsustained ventricular tachycardia (VT), and inducible sustained VT not suppressed by Class I drugs. Few data exist regarding implementation of this indication in clinical practice. We surveyed 72 active ICD implanting centers (26 United States, 46 Europe) with respect to screening and implantation practices related to MADIT for the year 1998. Prophylactic ICD implantation using MADIT indications comprised 9% of all initial implants (15% United States, 9% Germany, 5% other European), but ranged broadly from 0% (11 centers) to < 20% (7 centers). Implant rate was related to total annual ICD volume: 13% at high volume (> 100) and 7% at low volume (< 40) centers. Only 4% of responders conducted systematic Holter screening of postinfarction patients with low EF, and 41% screened for MADIT indications only in patients referred specifically for that purpose. Among implanting physicians (1) 61% do not routinely perform drug testing following induction of qualifying VT, (2) 38% would implant an ICD in selected patients with nonsustained VT and EF < 35% if qualifying VT was induced, (3) 18% would implant ICDs in selected patients without nonsustained VT, but with EF< 35% if qualifying VT was induced. Extrapolation of these results to the total number of new implants in 1998 suggests that approximately 5000 ICDs were placed for MADIT indications. However, individual practices were highly variable, with some extrapolation from strict indications based on patient presentation and physician judgment. A.N.E. 2000; 5(3):248–254
The Utility of Holter Monitoring Compared to Loop Recorders in the Evaluation of Syncope and Presyncope
Authors: Krahn Andrew D. , Renner Suzanne M. , Klein George J. , Yee Raymond , Skanes Allan , Evans Edward M.
Published: October 2006

Background:Holter monitoring is frequently used to assess patients with syncope, but rarely provides a diagnosis. Newer loop recorders provide the opportunity for prolonged electrocardiographic monitoring to enhance diagnostic yield.

Methods:The results of 232 Holter monitors and 81 loop recordings performed for the investigation of syncope or presyncope were reviewed for indication, patient demographics, and presence and type of symptoms and/or arrhythmias. The results were classified as (1) symptom‐arrhythmia correlation, (2) clinically useful information (group 1 plus those excluding arrhythmic syncope, and those demonstrating asymptomatic serious arrhythmias) and (3) unhelpful (asymptomatic and no serious arrhythmias).

Results:Loop recorders provided a symptom‐arrhythmia correlation in 11.1% of patients compared to only 0.4% in the Holter group (P < 0.0001). Clinically useful information was obtained in 54.3% of loop patients compared to 27.6% in the Holter group (P < 0.0001). Technical problems occurred in 0.4% of the Holter patients and in 3.7% of loop patients (P = 0.05). Classification was difficult in seven patients in the Holter group; two experienced symptoms during sinus rhythm but also had a serious asymptomatic arrhythmia, and five patients had 6–10 beats of asymptomatic ventricular tachycardia at a rate < 160 beats/min.

Conclusion:Loop recording was well tolerated and superior to Holter monitoring in providing a symptom‐arrhythmia correlation or clinically useful information in patients with syncope and presyncope. An initial approach with a loop‐recording device should be employed in these patients.
Optimal Target Heart Rate for Exercise‐Induced T‐Wave Alternans
Authors: Turitto Gioia , Caref Edward B. , El‐Attar Gamal , Helal Magda , Mohamed Assem , Pedalino Ronald P. , El‐Sherif Nabil
Published: October 2006

Objectives: This study was conducted to determine the optimal target heart rate (HR) for the use of exercise‐induced T‐wave alternans (TWA) as an index for risk of malignant ventricular tachyarrhythmias.

Background: Rate‐dependent TWA is an index of vulnerability to ventricular tachyarrhythmias. However, false positive TWA was reported to occur in normal subjects at high HR.

Methods: Two groups were evaluated: Group I: 50 patients with malignant ventricular tachyarrhythmias, who received an implantable cardioverter‐defibrillator (ICD); and Group II: 55 agematched normal subjects. In both Groups, TWA was evaluated during symptom‐limited bicycle exercise test.

Results: Peak HR during exercise test was 103 ± 17 beats/min in Group I, versus 124 ± 18 beats/min in Group II (P < 0.001). In Group I, 4 patients were excluded from analysis, due to high noise level or frequent ectopy during exercise. Out of the remaining 46 patients, TWA was present in 28 patients (61%), and absent in 18 (39%). In group II, TWA was present in four subjects (7%), and absent in 51 (93%). HR at the onset of TWA was 91 ± 11/min in Group I, and 119 ± 12/min in Group II (P < 0.001). Receiver operated characteristics curves demonstrated that a HR of 115 beats/min was the cutoff with the best sensitivity and specificity for TWA (100 and 96%, respectively). None of the patients in Group I developed TWA at HR > 115 beats/min, while two out of four in Group II had TWA at HR > 115/minutes. However, 13 patients in Group I who had no TWA were unable to exercise to a peak HR > 115 beats/min, compared to nine subjects in Group II.

Conclusions: A target HR of 115 beats/min was highly sensitive and specific for determination of exercise‐induced TWA as an index of risk of malignant ventricular tachyarrhythmias. However, a significant number of patients may not be able to achieve this target HR, resulting in an indeterminate test. The value of pharmacologic testing in this group should be assessed. A.N.E. 2001;6(2):123–128
Hormone Replacement Therapy Shortens QT Dispersion in Healthy Postmenopausal Women
Authors: Yildirir Aylin , Aybar Funda , Kabakci M. Giray , Yarali Hakan , Akgul Ebru , Bukulmez Orhan , Tokgozoglu S. Lale , Gurgan Timur , Oto All
Published: October 2006

Background: The aim of the study was to investigate the effects of hormone replacement therapy (HRT) on myocardial repolarization characteristics in postmenopausal women without coronary artery disease.

Methods: Fifty‐one consecutive healthy postmenopausal women (age 48 ±; 5) with negative exercise stress testing were prospectively enrolled into the study. Standard 12‐lead electrocardiograms were obtained to evaluate the effects of 6 months of HRT on QT intervals, corrected QT intervals (QTcmax and QTcmin), QT dispersion (QTd), and corrected QTd (QTcd). Hormone regimens were continuous 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate (MPA) or 0.625 mg/day CEE alone depending on the hysterectomy status.

Results: Although not statistically significant, CEE alone or in combination with MPA increased QTmax and QTmin values. However, the increase in QTmin was greater than the increase in QTmax, which resulted in statistically significant shortening of QTd (P = 0.007 in CEE and P < 0.001 in CEE + MPA groups). There was a significant prolongation of QTcmin values after 6 months in patients assigned to the CEE group (P = 0.001). The QTcd values were significantly shortened by HRT with both regimens (for CEE group 49 ±; 13 ms vs 38 ±; 13 ms, P = 0.01; for CEE + MPA group 49 ±; 14 ms vs 36 ±; 13, P < 0.001).

Conclusion: HRT significantly decreased the QTd and QTcd in postmenopausal women without coronary artery disease, independent of the addition of MPA to the regimen. This improvement in myocardial repolarization may be one of the mechanisms of the favorable effects of HRT on cardiovascular system. However, the clinical implications of the shortening of QTd in postmenopausal women with HRT must be clarified. A.N.E. 2001; 6(3):193–197
Predicting the Recurrence of Ventricular Tachyarrhythmias from T‐Wave Alternans Assessed on Antiarrhythmic Pharmacotherapy: A Prospective Study in Patients with Dilated Cardiomyopathy
Authors: Sakabe Koichi , Ikeda Takanori , Sakata Takao , Kawase Ayaka , Kumagai Kenta , Tezuka Naoki , Takami Mitsuaki , Nakae Takeshi , Noro Mahito , Enjoji Yoshihisa , Sugi Kaoru , Yamaguchi Tetsu
Published: October 2006

Background: Microvolt T‐wave alternans (TWA) has been proposed as a useful index to identify patients at risk of ventricular tachyarrhythmias. Recent studies have demonstrated that antiarrhythmic drugs, such as amiodarone and procainamide, decrease the prevalence of TWA. In this study, we tested whether TWA in patients on antiarrhythmic pharmacotherapy significantly predicts the recurrence of ventricular tachyarrhythmias in patients with dilated cardiomyopathy.

Methods: To evaluate the ability to predict the recurrence of ventricular tachyarrhythmias, determinate TWA and left ventricular ejection fraction (LVEF) were prospectively assessed in 49 patients with ischemic or nonischemic dilated cardiomyopathy on antiarrhythmic pharmacotherapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The pharmacotherapy consisted of class I (17 patients), III (29 patients), and IV (3 patients) antiarrhythmic drugs. The study endpoint was the first recurrence of sustained VT or VF on treatment during the follow‐up period.

Results: TWA was positive on antiarrhythmic pharmacotherapy in 30 patients (61%). During a follow‐up of 13 ±; 11 months, the sustained VT or VF recurred in 21 of the 41 patients (51%) with available follow‐up data. The sensitivity of TWA and LVEF for predicting recurrence of ventricular tachyarrhythmias was 76 and 38%, specificity was 60 and 70%, positive predictive value was 67 and 57%, and negative predictive value was 71 and 52%. Kaplan‐Meier event‐free analysis revealed that TWA was a significant risk stratifier (P = 0.02), whereas LVEF was not.

Conclusions: This prospective study suggests that TWA significantly predicts the recurrence of ventricular tachyarrhythmias, even on antiarrhythmic pharmacotherapy, in patients with dilated cardiomyopathy. TWA may also be a useful marker for evaluating the efficacy of antiarrhythmic drugs for ventricular tachyarrhythmias. A.N.E. 2001; 6(3):203–208
Analysis of P Wave and P Dispersion in Children with Secundum Atrial Septal Defect
Authors: Fei Ho Ting , Ling Chia Ee , Chin‐Ling Yip William , Yee Chan Kit
Published: October 2006

Background: P maximum and P dispersion are evaluated as predictors of paroxysmal atrial fibrillation in adults. In this study, these variables are being investigated in children with secundum ASD in comparison with that of normal controls and in relation to size of ASD and the presence or absence of atrial dilation.

Methods: Ninety‐four children with isolated secundum ASD (33 boys, 60 girls; mean ± SD age at diagnosis 2.9 ± 4.1 years) and 65 age‐matched controls (mean ± SD age 4.2 ± 4.2 years) were evaluated. Resting 12‐lead ECG was used to measure P waves from which P maximum and P dispersion (difference between maximum and minimum P‐wave duration) were derived. ASD children were arbitrarily subgrouped according to ASD sizes (small: 1–3 mm, moderate: 4–7 mm, large: 8 mm). The presence of right atrial dilation was noted from echocardiography.

Results: Children with ASD had significantly longer mean P dispersion compared to controls (P dispersion: 30.2 ± 11.1 vs 26.4 ± 6.6 ms, P = 0.008). Mean P maximum and P dispersion were significantly prolonged with increasing ASD size (P < 0.001). Children with right atrial dilation had significantly longer P maximum (102.3 ± 15.2 vs 82.8 ‐13.4 ms, P < 0.001) and larger P dispersion (36.1 ± 12.5 vs 27.6 ± 9.4 ms, P = 0.003) compared to those without right atrial dilation.

Conclusion: Prolonged atrial conduction time and inhomogeneity of atrial conduction may possibly be present in children with moderate to large sized ASD and in those with atrial dilation. A.N.E. 2001;6(4):305–309
Postextrasystolic Repolarization Abnormalities in ST‐U Segment in Patients with Ventricular Arrhythmias
Authors: Trusz‐Gluza Maria , Szydlo Krzysztof , Kukla Piotr , Wozniak‐Skowerska Iwona , Filipecki Artur , Peszek Ewa , Wojcik Ewelina
Published: October 2006

Background: Changes in U‐wave amplitude after premature ventricular contractions (PVC) are known as prognostic markers in the long QT syndrome dependent on bradycardia. The purpose of the study was to find correlation between postextrasystolic ST‐U segment changes and a history of sustained ventricular tachycardia or ventricular fibrillation (VT/VF).

Methods: The ST‐U segment configurations were taken from the 24‐hour ambulatory ECG. The comparison of the morphology of these segments was performed between sinus beats preceding PVC's and first postextrasystolic beats.

Population: Two groups of patients were evaluated: 1) 32 patients with VT/VF history (VT/VF group), and 2) 36 patients with potentially malignant arrhythmia (structural heart disease with frequent PVCs and/or nonsustained VT‐nsVT) tnon‐VT/VF group).

Results: We found T‐wave changes in 8 patients (25%) from the VT/VF group and in 12 patients (33.3%) from the nonVT/VF group (P = NS) and U‐wave changes in 13 patients (40.6%) and 3 patients (8.3%), respectively (P < 0.05). Other ECG indexes related to PVC's were also considered: RR interval, coupling interval (Cl), prematurity index (Pl), and postextrasystolic pause (PP). The analysis of these ECG indices revealed, when compared with patients without T‐U‐wave changes, that the occurrence of U‐wave changes was significantly related to longer RR interval of the sinus rhythm preceding PVC: 1025 ± 211 vs 918 ± 200 ms (P < 0.05). The prematurity index was lowest in patients with U‐wave changes: 0.54 ± 0.12 vs 0.65 ± 0.16 (P < 0.01) while postextrasystolic pauses leading to the postextrasystolic U‐wave changes were significantly longer: 1383 ± 223 vs 1130 ± 247 ms (P < 0.001). Cl did not differentiate patients: 556 ± 108 vs 584 ± 117 ms (P = NS).

Conclusions: Postextrasystolic changes in ST‐U segment configuration are dependent on bradycardia, low prematurity index of the PVC, and the lengthening of the postextrasystolic pause. U‐wave changes more frequently appeared in patients with malignant arrhythmias. Follow‐up study is needed to assess if they might be predictive for the occurrence or reoccurrence of arrhythmic episodes. A.N.E. 2002;7(1):17–21
Correction for Heart Rate Is Not Necessary for QT Dispersion in Individuals without Structural Heart Disease and Patients with Ventricular Tachycardia
Authors: Vassilikos Vassilios P. , Karagounis Labros A. , Psichogios Apostolos , Maounis Themistoclis , Iakovou John , Manolis Antonis S. , Cokkinos Dennis V.
Published: October 2006

Background: It remains controversial whether QT dispersion should be corrected for heart rate, especially when the limitations of rate correction formulae are considered. We investigated whether incremental atrial pacing affects QT dispersion and the rate‐corrected values according to Bazett's formula in individuals without structural heart disease and in patients with history of sustained ventricular tachycardia.

Methods: We studied 32 individuals without structural heart disease (group A), and 16 patients with a history of sustained ventricular tachycardia (group B). QT dispersion and corrected for heart rate QT dispersion using Bazett's formula (QTc dispersion) were calculated in sinus rhythm, and during continuous right atrial pacing for one minute at 100 and 120 beats/min.

Results: Interobserver variability was not significant (P ≧ 0.10). QT dispersion did not differ at rest between groups A and B and did not change significantly from baseline at any heart rate in both groups. However, QTc dispersion increased significantly with atrial pacing in a similar manner in group A and group B (42 ± 19 ms at rest vs 53 ± 23 ms at 120 beats/min, P < 0.001 for group A, 39 ± 16 ms at rest vs 60 ± 19 ms at 120 beats/min, P < 0.001 for group B).

Conclusions: We conclude that QT dispersion remains unchanged during atrial pacing at heart rates up to 120 beats/min in both individuals without structural heart disease and in patients with a history of sustained ventricular tachycardia. Correction by Bazett's formula results in prolongation of QTc dispersion, yielding values which may be misleading. A.N.E. 2002;7(1):47–52