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IntroductionSignal-averaged electrocardiography (SAECG) provides diagnostic and prognostic information regarding cardiac diseases. However, its value in other nonischemic cardiomyopathies (NICMs) remains unclear. This study aimed to investigate the role of SAECG in patients with NICM.Methods and resultsThis retrospective study included consecutive patients with NICM who underwent SAECG, biventricular substrate mapping, and ablation for ventricular arrhythmia (VA). Patients with baseline ventricular conduction disturbances were excluded. Patients who fulfilled at least one SAECG criterion were categorized into Group 1, and the other patients were categorized into Group 2. Baseline and ventricular substrate characteristics were compared between the two groups. The study included 58 patients (39 men, mean age 50.4 ± 15.5 years), with 34 and 24 patients in Groups 1 and 2, respectively. Epicardial mapping was performed in eight (23.5%) and six patients (25.0%) in Groups 1 and 2 (p = 0.897), respectively. Patients in Group 1 had a more extensive right ventricular (RV) low-voltage zone (LVZ) and scar area than those in Group 2. Group 1 had a larger epicardial LVZ than Group 2. Epicardial late potentials were more frequent in Group 1 than in Group 2. There were more arrhythmogenic foci within the RV outflow tract in Group 1 than in Group 2. There was no significant difference in long-term VA recurrence.ConclusionIn our NICM population, a positive SAECG was associated with a larger RV endocardial scar, epicardial scar/late potentials, and a higher incidence of arrhythmogenic foci in the RV outflow tract.

Background and Objectives: Holter-based late potentials (LPs) are useful for predicting lethal arrhythmias in organic cardiac diseases. Although Holter-based LPs exhibit diurnal variation, no studies have evaluated the optimal timing of LP measurement over 24 h for predicting lethal arrhythmia that leads to sudden cardiac death. Thus, this study aimed to validate the most effective timing for Holter-based LP testing and to explore factors influencing the diurnal variability in LP parameters. Materials and Methods: We retrospectively analyzed 126 patients with post-myocardial infarction (MI) status and 60 control participants who underwent high-resolution Holter electrocardiography. Among the 126 post-MI patients, 23 developed sustained ventricular tachycardia (VT) (the MI-VT group), while 103 did not (the MI-non-VT group) during the observation period. Holter-based LPs were measured at 0:00, 4:00, 8:00, 12:00, 16:00, and 20:00, and heart rate variability analysis was simultaneously performed to investigate factors influencing the diurnal variability in LP parameters. Results: Holter-based LP parameters showed diurnal variation with significant deterioration at night and improvement during the day. Assessment at the time with the longest duration of low-amplitude signals < 40 μV in the filtered QRS complex terminus (LAS40) gave the highest receiver operating characteristics curve (area under the curve, 0.659) and the highest odds ratio (3.75; 95% confidence interval, 1.45–9.71; p = 0.006) for predicting VT. In the multiple regression analysis, heart rate and noise were significant factors affecting the LP parameters in the MI-VT and control groups. In the non-VT group, the LP parameters were significantly influenced by noise and parasympathetic heart rate variability parameters, such as logpNN50. Conclusions: For Holter-based LP measurements, the test accuracy was higher when the LP was measured at the time of the highest or worst value of LAS40. Changes in autonomic nervous system activity, including heart rate, were factors influencing diurnal variability. Increased parasympathetic activity or bradycardia may exacerbate Holter-based LP parameters. [ABSTRACT FROM AUTHOR]

Background and Objectives: Holter-based late potentials (LPs) are useful for predicting lethal arrhythmias in organic cardiac diseases. Although Holter-based LPs exhibit diurnal variation, no studies have evaluated the optimal timing of LP measurement over 24 h for predicting lethal arrhythmia that leads to sudden cardiac death. Thus, this study aimed to validate the most effective timing for Holter-based LP testing and to explore factors influencing the diurnal variability in LP parameters. Materials and Methods: We retrospectively analyzed 126 patients with post-myocardial infarction (MI) status and 60 control participants who underwent high-resolution Holter electrocardiography. Among the 126 post-MI patients, 23 developed sustained ventricular tachycardia (VT) (the MI-VT group), while 103 did not (the MI-non-VT group) during the observation period. Holter-based LPs were measured at 0:00, 4:00, 8:00, 12:00, 16:00, and 20:00, and heart rate variability analysis was simultaneously performed to investigate factors influencing the diurnal variability in LP parameters. Results: Holter-based LP parameters showed diurnal variation with significant deterioration at night and improvement during the day. Assessment at the time with the longest duration of low-amplitude signals < 40 μV in the filtered QRS complex terminus (LAS40) gave the highest receiver operating characteristics curve (area under the curve, 0.659) and the highest odds ratio (3.75; 95% confidence interval, 1.45–9.71; p = 0.006) for predicting VT. In the multiple regression analysis, heart rate and noise were significant factors affecting the LP parameters in the MI-VT and control groups. In the non-VT group, the LP parameters were significantly influenced by noise and parasympathetic heart rate variability parameters, such as logpNN50. Conclusions: For Holter-based LP measurements, the test accuracy was higher when the LP was measured at the time of the highest or worst value of LAS40. Changes in autonomic nervous system activity, including heart rate, were factors influencing diurnal variability. Increased parasympathetic activity or bradycardia may exacerbate Holter-based LP parameters.

Background: The utility of late potentials on signal-averaged electrocardiography (SAECG) for risk stratification in patients with Brugada syndrome (BrS) remains controversial. Late potentials on conventional SAECG with Frank leads may be insufficiently sensitive to detect site-specific late potentials in right precordial leads.Objective: The purpose of this study was to evaluate the utility of site-specific late potentials using a novel unipolar Holter-SAECG system for risk stratification in patients with BrS.Methods: Consecutive symptomatic (n = 20) and asymptomatic (n = 21) patients with BrS who underwent investigation using conventional SAECG and a novel unipolar Holter-SAECG system were enrolled. We evaluated clinical characteristics and outcomes and compared late potentials on the 2 SAECGs between both groups and patients with and without cardiac events (CEs) (sudden cardiac death or sustained ventricular tachyarrhythmias) during the follow-up period.Results: During mean follow-up of 76 months, 10 patients (24%) had CEs. There were no significant differences in late potentials on conventional SAECG between symptomatic and asymptomatic patients. On the Holter-SAECG system, RMS40 in lead V2 in the third intercostal space (3L-V2) at the nighttime was significantly lower in the symptomatic group than in the asymptomatic group (5.5 ± 0.8 μV and 8.2 ± 0.8 μV, respectively; P = .027). Univariate analysis of predictive values for CE showed that hazard ratios of daytime and nighttime RMS40 in lead 3L-V2 of <7.7 μV and <6.1 μV were 7.58 and 6.14, respectively.Conclusion: Site-specific late potentials in lead 3L-V2 measured using the novel Holter-SAECG system may be a useful marker for high-risk patients with BrS. [ABSTRACT FROM AUTHOR]

Abstract Background Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of frequency domain microvolt T‐wave alternans (TWA), signal‐averaged ECG (SAECG), and heart rate turbulence (HRT) using 24‐hour Holter ECG for detecting cardiac involvement in patients with pulmonary sarcoidosis. Methods This study consisted of consecutive 40 pulmonary sarcoidosis patients (11 males, 62 ± 13 years) who underwent 24‐hour Holter monitoring with and without cardiac involvement. All patients underwent frequency domain TWA, SAECG, and HRT using 24‐hour Holter monitoring. Patients with atrial fibrillation pacing or wide QRS electrocardiogram were excluded. Results After 14 patients were excluded, a total of 26 patients (six males, 59 ± 14 years) were evaluated. Seven patients had cardiac involvement (cardiac sarcoidosis [CS] group). On the Holter SAECG, duration of low‐amplitude signals

Abstract Background and objectives Athlete’s heart is characterized by structural cardiac changes, including enlargement and hypertrophy. However, exercise-induced cardiac electrical remodeling is not well known in Asian athletes. We sought to evaluate the association between vigorous exercise and the development of abnormal late potential on signal-averaged electrocardiogram (SAECG). Method We analyzed 48 Korean professional soccer players and 71 healthy sedentary controls who underwent SAECG and transthoracic echocardiography at Kyung Hee University Hospital. An SAECG was considered abnormal (positive for ventricular late potential) when any one of the three following criteria was met: filtered QRS duration > 114 ms, root-mean-square voltage in the terminal 40 ms 114 ms (7.0% vs. 22.9%, P = 0.013) and lower terminal QRS root-mean-square voltage

Background: P-wave signal-averaged electrocardiography (P-SAECG) quantifies atrial electrical activity. P-SAECG measures and their clinical correlates and heritability have had limited characterization in community-based cohorts.Objective: The purpose of this study was to (1) establish reference values; (2) identify clinical risk factors associated with P-SAECG; and (3) estimate genetic heritability for P-SAECG traits.Methods: We performed P-SAECG in 2 generations of Framingham Heart Study participants. We performed backward elimination regression models to assess associations of clinical factors with each SAECG trait (P-wave [PW] duration, root mean square voltage in terminal 40 ms [RMS40], terminal 30 ms RMS30, terminal 20 ms RMS20, RMS PW, and PW integral). We estimated the adjusted genetic heritability of P-SAECG measures using the Sequential Oligogenic Linkage Analysis Routines (SOLAR) program.Results: We included 4307 participants (age 55 ± 14 years; 56% female). The reference values were derived from 1752 participants without cardiovascular risk factors. Median (2.5th percentile; 97.5th percentile) total PW duration was 118 ms (93; 146) in women and 128 ms (104; 158) in men in the reference sample, and 121 ms (94; 151) in women and 129 ms (103; 159) in the entire study cohort (broad sample). In the broad sample, after adjusting for age and sex, total PW duration was positively associated with height, weight, prevalent heart failure, history of atrial fibrillation (AF), and atrioventricular node blockers, and negatively associated with smoking, waist circumference, heart rate, and diabetes. The estimated heritability of P-SAECG traits was moderate, ranging from 11.9% for RMS30 to 24.9% for PW integral.Conclusion: P-SAECG traits are associated with multiple AF-related risk factors and are moderately heritable. [ABSTRACT FROM AUTHOR]

Background: Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of frequency domain microvolt T‐wave alternans (TWA), signal‐averaged ECG (SAECG), and heart rate turbulence (HRT) using 24‐hour Holter ECG for detecting cardiac involvement in patients with pulmonary sarcoidosis. Methods: This study consisted of consecutive 40 pulmonary sarcoidosis patients (11 males, 62 ± 13 years) who underwent 24‐hour Holter monitoring with and without cardiac involvement. All patients underwent frequency domain TWA, SAECG, and HRT using 24‐hour Holter monitoring. Patients with atrial fibrillation pacing or wide QRS electrocardiogram were excluded. Results: After 14 patients were excluded, a total of 26 patients (six males, 59 ± 14 years) were evaluated. Seven patients had cardiac involvement (cardiac sarcoidosis [CS] group). On the Holter SAECG, duration of low‐amplitude signals <40 μV in the terminal filtered QRS complex (LAS40) was significantly higher, and root mean square voltage of the terminal 40 ms of the filtered QRS complex (RMS40) was significantly lower in the CS group compared with the non‐CS group (LAS40: 61.4 ± 35.9 vs 37.6 ± 9.2 ms; P =.018, RMS40: 11.4 ± 10.3 vs 23.6 ± 13.2 ms; P =.023). Prevalence of positive late potential (LP) was also significantly higher in the CS group than that in the non‐CS group (85.7% vs 31.5%; P =.026). The sensitivity, specificity, positive, and negative predictive values of LP for identifying patients with cardiac involvement were 85.7%, 68.4%, 50.0%, and 92.8%, respectively. Conclusion: Holter SAECG may be useful for detecting cardiac involvement in patients with pulmonary sarcoidosis. [ABSTRACT FROM AUTHOR]

Introduction: Signal-averaged electrocardiography (SAECG) provides diagnostic and prognostic information regarding cardiac diseases. However, its value in other nonischemic cardiomyopathies (NICMs) remains unclear. This study aimed to investigate the role of SAECG in patients with NICM., Methods and Results: This retrospective study included consecutive patients with NICM who underwent SAECG, biventricular substrate mapping, and ablation for ventricular arrhythmia (VA). Patients with baseline ventricular conduction disturbances were excluded. Patients who fulfilled at least one SAECG criterion were categorized into Group 1, and the other patients were categorized into Group 2. Baseline and ventricular substrate characteristics were compared between the two groups. The study included 58 patients (39 men, mean age 50.4 ± 15.5 years), with 34 and 24 patients in Groups 1 and 2, respectively. Epicardial mapping was performed in eight (23.5%) and six patients (25.0%) in Groups 1 and 2 ( p  = 0.897), respectively. Patients in Group 1 had a more extensive right ventricular (RV) low-voltage zone (LVZ) and scar area than those in Group 2. Group 1 had a larger epicardial LVZ than Group 2. Epicardial late potentials were more frequent in Group 1 than in Group 2. There were more arrhythmogenic foci within the RV outflow tract in Group 1 than in Group 2. There was no significant difference in long-term VA recurrence., Conclusion: In our NICM population, a positive SAECG was associated with a larger RV endocardial scar, epicardial scar/late potentials, and a higher incidence of arrhythmogenic foci in the RV outflow tract., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Nguyen, Lin, Chung, Chang, Lo, Lin, Chang, Hu, Tuan, Chao, Liao, Kuo, Liu, Liu, Wu, Kuo, Li, Huang, Wu, Siow, Bautista, Cao and Chen.)

Background: Ventricular fibrillation and atrial fibrillation are well-known arrhythmias in patients with Brugada syndrome. This study evaluated the characteristics of the atrial arrhythmogenic substrate using the signal-averaged electrogram (SAECG) in patients with Brugada syndrome. Methods: SAECGs were performed during normal sinus rhythm in 23 normal volunteers (control group), 21 patients with paroxysmal atrial fibrillation (PAF; PAF group), and 21 with Brugada syndrome (Brugada group). Results: The filtered P wave duration (fPd) in the control, Brugada, and PAF groups was 113.9 ± 12.9 ms, 125.3 ± 15.0 ms, and 137.1 ± 16.3 ms, respectively. The fPd in the PAF group was significantly longer compared to that in the control and Brugada groups (p

P-wave signal-averaged electrocardiography (P-SAECG) can detect imperceptible conduction abnormalities, and volume analysis using two-dimensional speckle-tracking echocardiography (2-DSTE) allows us to easily measure the phasic function of the left atrium (LA). Both conduction abnormalities and functional deformation of the LA may be linked to the clinical outcome; however, the exact relationship is unclear. The aim of this study was to investigate the relationship between the phasic function of the LA and electrical conduction using P-SAECG and 2-DSTE. The subjects were 112 male volunteers (age 46.9 ± 13.2 years) with normal cardiac function who underwent P-SAECG and 2-DSTE. The filtered p-wave duration (FPD) and the root-mean-square voltage for the last 20 ms (RMS20) on P-SAECG wave were measured in ms and μV, respectively. Total emptying function (EF) (reservoir function), passive EF (conduit function), and active EF (booster pump function) of the LA were calculated as percentages to evaluate phasic LA function using 2DSTE. The mean FPD was 134.3 ± 11.7 ms and the mean RMS20 was 4.59 ± 2.39 μV. The mean total EF was 60.5 ± 13.1%, mean passive EF was 39.4 ± 13.9%, and mean active EF was 35.1 ± 13.9%. FPD had a negative correlation with passive EF (r = − 0.20, p = 0.039). FPD showed no significant relationship with total EF (r = − 0.03, p = 0.78) or active EF (r = 0.13, p = 0.18). There was a significant association between RMS20 and passive EF (r = 0.19, p = 0.048); however, no there was no correlation between RMS20 and total EF (r = 0.12, p = 0.23), or between RMS20 and passive EF (r = − 0.02, p = 0.86). In multivariate regression analysis, passive EF was an independent factor that influenced FPD duration. This study indicated that FPD was associated with conduit function, which includes phasic LA function. Therefore, electrical conduction of the LA and left ventricular diastolic function are closely related. In the clinical setting, when conduction abnormalities are detected, lifestyle measures or interventions can be applied to reduce cardiovascular risk. [ABSTRACT FROM AUTHOR]

AMAÇ: Sinyal ortalamalı elektrokardiyografi miyokardiyal hasarla oldukça ilişkili olan geç potansiyeller olarak adlandırlan düşük amplitüdlü sinyalleri saptar. Bu çalışmadaki amacımız, doksorubisinin miyokardiyal yan etkileri ile sinyal ortalamalı elektrokardiyogram arasındaki potansiyel ilişkiyi araştırmaktır. YÖNTEM: Doksorubisin içeren kemoterapi alan 48 hasta çalışmaya dahil edildi. Sinyal ortalamalı elektrokardiyografi, 3 parametre kullanılarak ölçüldü: filtrelenmiş QRS (fQRS), fQRS süresinin son 40 milisaniyesi boyunca saptanan voltajın karekökü (RMS40), fQRS in son 40 milisaniyesinden başlayarak 40μV altına düştükten sonraki geçen süre (HFLA40). Hastaların ejeksiyon fraksiyonları, ekokardiyografi ile ölçüldü. SONUÇLAR: Ortalama yaş 44 (27-70) yıl idi. Ortalama kümülatif doksorubisin dozu 475.56±98.45 mg idi. Ölçülen sinyal ortalamalı elektrokardiyografik parametrelerin ortalama süreleri şöyleydi: fQRS:78.27±10.74 milisaniye, RMS40: 115.10±50.23 ve HFLA: 21.95±8.39 mikrovolt idi. Doksorubisin dozu ile fQRS arasında pozitif korelasyon saptanırken (r=0.28, p=0.02), RMS40 arasında negatif korelasyon mevcuttu (r=-.31,p=0.03). Doksorubisin dozu ile ejeksiyon fraksiyonları arasında korelasyon saptanmadı (r=.18, p=0.22). TARTIŞMA: Bulgularımız, kümülatif doksorubisin dozları ile fQRS ve RMS40 arasında anlamlı korelasyon olduğunu düşündürmektedir. Bu yüzden sinyal ortalamalı elektrokardiyografik parametreler doksorubisin içeren tedaviler alan hastalarının prognozunu belirlemede değerli olabilir.

BACKGROUND: Signal-averaged electrocardiography detects low-amplitude signals designated as late potentials which are strongly related to myocardial damage. We aimed to search for the possible relation between the myocardial effects of doxorubicin and signal-averaged electrocardiographic parameters. METHODS: Fortyeight patients who received doxorubicin included chemotherapy were enrolled. Signal-averaged electrocardiographic parameters were detected by using 3 parameters; filtered QRS (fQRS), the square root of the voltage obtained during the last 40 milliseconds of the duration of fQRS (RMS40), the duration starting from the last 40 miliseconds of fQRS till the decrease of voltage under 40 microvolts. (HFLA40). Ejection fractions of the patients were measured by echocardiographic evaluation. RESULTS: Median age was 44 (27-70) years. Mean cumulative doxorubicin dosage was 475.56±98.45 mg. Mean values of the measured signal-averaged electrocardiographic parameters were as follows; fQRS: 78.27±10.74 miliseconds, RMS40:115.10±50.23 and HFLA was 21.95±8.39 microvolts . The doses of doxorubicin showed a positive correlation with fQRS (r=0.28, p=0.02) and a negative correlation with RMS40 (r=-.31,p=0.03). There was no correlation between the doxorubicin dosage and the ejection fraction of the patients (r=.18, p=0.22). CONCLUSION: Our results suggested that significant correlations are present between fQRS and RMS40 and cumulative doxorubicin dosages. Therefore, signal-averaged electrocardiographic parameters may be of value for predicting the prognosis of the patients who have received doxorubicin included chemotherapy. [Cukurova Med J 2013; 38(2.000): 241-249]

Background: Sudden cardiac death is a leading cause of death in patients with ST-elevation myocardial infarction (MI). According to high cost of modern therapeutic modalities it is of paramount importance to define protocols for risk stratification of post-MI patients before considering expensive devices such as implantable cardioverter-defibrillator.Methods: One hundred and thirty seven patients with acute ST-elevation MI were selected and underwent echocardiographic study, holter monitoring and signal-averaged electrocardiography (SAECG). Then, the patients were followed for 12 ±3 months.Results: During follow-up, 13 deaths (9.5%) occurred; nine cases happened as sudden cardiac death (6.6%). The effect of ejection fraction (EF) less than 40% on occurrence of arrhythmic events was significant (P

Purpose: There has been growing interest in cardiac disturbances in epilepsy patients and their etiologic role in the context of sudden death. Ventricular late potentials (VLPs) recorded on signal-averaged electrocardiography (SAECG) reflects delayed ventricular depolarization and identifies the structural or functional substrate for the ventricular tachycardia in the reentry mechanism. Therefore, abnormal SAECG poses the potential of identifying patients at increased risk of malignant ventricular arrhythmias and sudden cardiac death. The aim of this exploratory study was to screen epilepsy patients who were treated with established doses of antiepileptic drugs (AEDs) on the presence of VLPs. Methods: Forty-five consecutive patients with the diagnosis of epilepsy and 19 healthy volunteers, aged younger than 46 years, participated in the study. Exclusion criteria included symptoms or signs of diseases other than epilepsy, in particular relating to heart disease or medication influencing the cardiovascular system, as well as seizure reported by patients that occurred <3 days before the ECG examination. The electrocardiogram was recorded according to the standard protocol. The seizure frequency was calculated based on the available data of epileptic events within the preceding 3 months. Disease duration was estimated by determining the time from the first reported seizure to the present. Key Findings: There were 22 patients (48%) in the epilepsy group and only one patient (5%) in the control group fulfilling the criteria for VLP (p = 0.0005). Subsequently, epilepsy patients were divided into two subgroups according to VLP presence. Patients with VLP had longer disease duration (p = 0.03) compared to those without VLP. Similarly, patients with VLP more frequently had refractory epilepsy (p = 0.03) and had higher monthly seizure frequency (p = 0.02). Analysis of the proportions of generalized seizures (GS) and focal seizures (FS) showed a tendency for higher number of generalized tonic-clonic seizures in the VLP group, but this did not reach statistical significance (p = 0.06). VLP patients tended to be more often on polytherapy (defined as more than one AED per patient) (p = 0.07) as compared to epilepsy patients without VLP. However, if the numbers of AEDs per patients among the subgroups were compared, patients with VLP were treated with more AEDs than patients without VLP (p = 0.01). The study was not sufficiently powered to pinpoint any particular drug or AED combination to influence the appearance of VLP in epileptic patients. In particular, there was no difference in valproate or carbamazepine exposure, considering the percentage of patients exposed or the total daily dose administered. Significance: Epilepsy patients more frequently display abnormal SAECGs with VLPs as compared to the control population, and their presence correlates with the disease duration, uncontrolled seizures, and polytherapy. Further longitudinal studies are needed in order to stratify the risk of life-threatening ventricular events in epilepsy patients with VLPs. [ABSTRACT FROM AUTHOR]

Background: Arrhythmic risk stratification in patients with Brugada syndrome remains controversial. Several recent reports have highlighted the possible role of late potential (LP) on the signal-averaged electrocardiogram (SAECG) as a noninvasive risk stratification tool in Brugada syndrome, but further prospective study is required before its general applicability. Objective: The purpose of this study was to investigate the role of LP in arrhythmic risk stratification of Brugada syndrome patients. Methods: Forty-three patients with Brugada syndrome were enrolled and divided into a symptomatic group (group A, n = 24) and an asymptomatic group (group B, n = 19). SAECG was performed to analyze the characteristics of LP in all subjects. The prospective study was conducted to observe the occurrence of arrhythmic events. Results: LP was positive in 22 (91.7%) of 24 patients in the symptomatic group and in 7 (36.8%) of 19 patients in the asymptomatic group. During mean follow-up of 33.8 ± 9.0 months, the incidence rate of arrhythmic events was 72.4% (21/29) in LP-positive [LP(+)] patients compared with 14.3% (2/14) in LP-negative [LP(−)] patients. Multivariate Cox proportional hazard analyses revealed that the presence of LP had the most significant hazard ratio of 10.9 (95% confidence interval 1.1–104.3, P = .038), with sensitivity of 95.7%, specificity 65.0%, positive predictive value 75.9%, negative predictive value 92.9%, and predictive accuracy 81.4%. Kaplan-Meier curves plotted for event-free survival according to LP showed a significant difference between LP(+) and LP(−) patients (log rank, P = .003). Conclusion: The results of this study support the role of LP detected by SAECG in arrhythmic risk stratification of Brugada syndrome patients. [Copyright &y& Elsevier]

Background: Preimplantation left ventricular dyssynchrony is considered a prerequisite for a beneficial response to cardiac resynchronization therapy (CRT). However, electrical dyssynchrony estimated by QRS duration (QRSd) on ECG has not been proven to be an optimal surrogate of mechanical dyssynchrony. We evaluated the correlation of mechanical dyssynchrony with QRSd as measured by signal-averaged electrocardiography (SAECG) in comparison with measurements based on conventional surface ECG and with onscreen measurements based on digital ECG. Methods: We included 49 consecutive patients with decompensated heart failure (40 men, aged 66.8 ± 9.5 years), New York Heart Association (NYHA) class II–IV, and LVEF ≤ 40%. QRSd was calculated by manual measurement of 12-lead ECG, on-screen measurement of computer-based ECG, and calculation of total ventricular activation time on SAECG. Results: Only 60.4% of the studied patients had QRS ≥ 120 ms based on measurements derived by SAECG compared to 69.4% by using on-screen measurement of computer-based ECG and 73.5% based on surface ECG (P = 0.041). Interventricular but not intraventricular delay was correlated with QRSd. The correlation of interventricular dyssynchrony with QRSd was stronger when measured by SAECG than by surface ECG (r = 0.45, P = 0.001 vs r = 0.35, P < 0.01). Among patients with ischemic cardiomyopathy, no significant correlation was demonstrated between mechanical dyssynchrony and QRSd. In nonischemic patients, interventricular delay was significantly correlated with QRSd measured by surface ECG (r = 0.45, P < 0.05) and SAECG (r = 0.46, P < 0.05). Conclusions: The use of SAECG results in different patient classification in wide QRS complex category as compared to surface ECG. Furthermore, QRSd measured by SAECG is correlated with interventricular but not intraventricular dyssynchrony in heart failure patients. [ABSTRACT FROM AUTHOR]

Background: The correlation between parameters of two-dimensional echocardiography and signal-averaged ECG (SAECG) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is not known well. Methods: Thirty-three patients (13 females, 40.3 ± 14.4 years old) were included in this study. Both the right and left ventricular dimensions and systolic function were assessed with two-dimensional echocardiography. The SAECG was performed with high-gain amplification and filtered using bidirectional Butterworth filters between 40 and 250 Hz. We evaluated the correlation between the parameters of the SAECG and two-dimensional echocardiography. Results: The right ventricular (RV) outflow tract was the most frequently (n = 18, 54%) involved segment. Six (18%) patients had only mildly decreased RV systolic function. All the other patients had normal RV systolic function. Although localized left ventricular wall motion abnormalities were observed in 14 (42%) patients, the left ventricular ejection fraction was normal in most (n = 32, 97%). Late potentials were positive in 22 (63%) patients. There was no significant correlation between parameters of the SAECG and two-dimensional echocardiography for the entire patient population. Conclusions: The SAECG parameters exhibited no correlation to any of two-dimensional echocardiography parameters in the patients with ARVC. Fragmented electrical activity may develop with no significant relation to the anatomical changes in the patients with ARVC. [ABSTRACT FROM AUTHOR]

Introduction: Although successful ablation of ventricular tachycardia (VT) is feasible in arrhythmogenic right ventricular cardiomyopathy (ARVC), long-term recurrence is common. The aim of this study was to assess the usefulness of a change in the isolated delayed component (IDC) as an endpoint of the catheter ablation in ARVC. Methods and Results: Eighteen patients (48 ± 11 years) with ARVC were studied. Detailed endocardial mapping of the right ventricle (RV) was performed during sinus rhythm. IDCs were recorded in 16 patients and the latest IDCs were related to the VT circuit. Catheter ablation was carried out in the areas with the IDCs. At the end of the session, the IDC was electrically dissociated in one, disappeared in five, exhibited second-degree block in one, was significantly delayed (≥50 ms) in three, and remained unchanged in six. The change in the IDC was correlated with the change in the type II/III late potentials in the signal-averaged electrocardiography (ECG) and the inducibility of the clinical VT after the ablation. During a follow-up of 61 ± 38 months, VT recurred in six. The patients with a changed IDC had a significantly lower VT recurrence than those with no IDC or an unchanged IDC (P < 0.02). Conclusion: In patients with ARVC, (1) the IDCs during sinus rhythm are related to the clinical VT and can be a target for the ablation, (2) a change in the IDC can be used as an endpoint, and (3) qualitative analyses of the serial signal-averaged ECGs may be useful for the long-term follow-up. [ABSTRACT FROM AUTHOR]

Objective: We present the improved method of recognition of sustained ventricular tachycardia (SVT) based on new filtering technique (FIR), extended signal-averaged electrocardiography (SAECG) description by 9 parameters and the application of support vector machine (SVM) classifier. Methods: The dataset consisted of 376 patients (100 patients with sustained ventricular tachycardia after myocardial infarction (MI) labelled as class SVT+, 176 patients without sustained ventricular tachycardia after MI and 77 healthy persons, 50% of data were left for validation. The analysis of SAECG was performed by 2 types of filtration: low pass four-pole IIR Butterworth filter and FIR filter with Kaiser window. We calculated 3 commonly used SAECG parameters: hfQRS (ms), RMS40 (μV), LAS<40 μV(ms) and 6 new parameters: LAS<25 (ms) - duration of the low amplitude <25μV signals at the end of QRS complex; RMS QRS(μV) - root mean square voltage of the filtered QRS complex; pRMS(μV) - root mean square voltage of the first 40ms of filtered QRS complex; pLAS(ms) - duration of the low amplitude <40μV signals in front of QRS complex; RMS t1(μV) - root mean square voltage of the last 10ms the filtered QRS complex; RMS t2(μV) - root mean square voltage of the last 20ms the filtered QRS complex. For the recognition of SVT+ class patients we used the SVM with the Gaussian kernel. Results: The results confirmed good generalization of obtained models. The recognition score (calculated as correct classification/total number of patients) of SVT+patients on data set containing 3 standard parameters (Butterworth filter) is 92.55%. The same score was obtained for data set containing 9 parameters (Butterworth filter). The best score (95.21%) was obtained for data set based on 9 parameters and FIR filter. Conclusion: Our approach improved risk stratification up to 95% based on SAECG due to the application of FIR filter, 6 new parameters and efficient statistical classifier, the support vector machine. [ABSTRACT FROM AUTHOR]

Introduction: Risk stratification between symptomatic and asymptomatic patients with Brugada syndrome is not yet established. We compared daily fluctuations in 12-lead electrocardiogram (ECG) and signal-averaged ECG (SAECG) characteristics between symptomatic and asymptomatic patients with Brugada syndrome to identify new markers for distinguishing between high- and low-risk patients. Methods and Results: Thirty-five patients with Brugada syndrome underwent ECG and SAECG simultaneously at least 4 times every 3 months. We evaluated daily fluctuations (differences between maximum and minimum values) in ECG and SAECG characteristics and compared them between symptomatic , and asymptomatic patients. On ECG, the daily fluctuations in r-J interval (interval from QRS onset to J point) in leads V1, V2, and V6 were significantly larger in symptomatic than in asymptomatic patients . On SAECG, daily fluctuations in filtered QRS (f-QRS) duration and LAS40 were significantly larger in symptomatic than in asymptomatic patients (f-QRS; , and LAS40; ). Conclusions: Instability of depolarization appears to be related to the risk of fatal ventricular arrhythmias in patients with Brugada syndrome. Daily fluctuations in ECG and SAECG characteristics could be useful for distinguishing between high- and low-risk patients with Brugada syndrome. [ABSTRACT FROM AUTHOR]

Abstract: Background: Several studies have documented the prognostic significance of the signal-averaged electrocardiogram (SAECG) both after myocardial infarction and nonischemic cardiomyopathy. However, whether the SAECG can identify patients with implantable cardioverter-defibrillator (ICD) who receive appropriate therapy has not been hitherto completely investigated. Methods: Between August 2002 and August 2004, 83 consecutive ICD patients who had had SAECGs recorded were enrolled in this study. All patients were followed up in the outpatient ICD clinic, and interrogated electrograms were collected. Results: Over 9.0 ± 2.8 months of follow-up, 27 (32%) patients had appropriate ICD therapy for ventricular tachycardia or fibrillation; 15 (55.6%) patients had abnormal; and the remaining 12 (44.4%) had normal SAECGs. Of the 56 patients with no appropriate therapy, 27 (48.2%) and 29 (51.8%) patients had abnormal and normal SAECGs, respectively. There were no statistically significant differences between the 2 groups in SAECG findings (P = .41). A Cox regression analysis showed that the left ventricular ejection fraction was the only predictor of appropriate therapy (P = .02). Subgroup analysis of the patients with coronary artery disease and spontaneous monomorphic ventricular tachycardia indicated that left ventricular ejection fraction (P = .03) and abnormal SAECG (P = .02) were predictors of appropriate therapy. Conclusions: Our data demonstrate that except for the subgroup of patients with coronary artery disease presenting with monomorphic ventricular tachycardia, the SAECG did not predict ventricular tachyarrhythmia recurrence and, hence, appropriate ICD therapy. Thus, SAECG findings should generally not be a factor in decision for ICD implantation. [Copyright &y& Elsevier]

Abstract: Magnetocardiography (MCG) is a method complementary to electrocardiography (ECG). We examined recording and reproducibility of atrial depolarization signal by MCG. Multichannel MCG over anterior chest and orthogonal 3-lead ECG were recorded in 9 patients who had paroxysmal lone atrial fibrillation and in 10 healthy subjects in duplicate at least 1 week apart. Data were averaged using atrial wave template and high-pass filtered at 25, 40, and 60 Hz. Atrial signal duration with automatic detection of onset and offset and root mean square amplitudes of the last portion of atrial signal were determined. Coefficient of variation of atrial signal duration by MCG at 40 Hz was 3.3% and difference between the measurements was 3.5 milliseconds on average. The corresponding figures obtained by signal-averaged ECG (SAECG) were 6.1% and 6.9 milliseconds. Coefficient of variation for root mean square of the last 40 milliseconds of atrial signal were 16% in MCG and 17% in SAECG. Reproducibility was best at 40-Hz filter and similar in patients and healthy subjects. In conclusion, the reproducibility of atrial signal variables in MCG is adequate and somewhat better than in SAECG and equal in patients with lone atrial fibrillation and healthy subjects. Magnetocardiography seems to be a potentially valuable method to evaluate features of atrial depolarization in patient studies. [Copyright &y& Elsevier]

Background: Recent studies suggest that the Brugada-type electrocardiogram (ECG) is much more prevalent than the manifest Brugada syndrome. Although invasive electrophysiologic investigations have been proposed as a risk stratifier, their value is controversial, and alternative noninvasive techniques may be preferred. We sought a noninvasive strategy to detect a high-risk group in a long-term follow-up study of subjects with a Brugada-type ECG, and no history of cardiac arrest. Methods: This study enrolled 124 consecutive subjects with a Brugada-type ECG. Prognostic indices included: age, sex, a family history of sudden death, syncopal episodes, a spontaneous coved-type ST-segment elevation, maximal magnitude of ST-segment elevation, a spontaneous change in ST segment, a mean QRS duration, maximal QT interval, QT dispersion, late potentials (LP) by signal-averaged ECG, and microvolt T-wave alternans. Results: Of the 124 subjects, 20 consenting subjects had an implantable defibrillator before follow-up. During a 40 ± 19-month follow-up, 12 subjects (9.7%) reached one of the endpoints (sudden death or ventricular tachyarrhythmia). Of the 12 risk indices, a family history of sudden death, syncopal episodes, a spontaneous coved-type ST-segment elevation, a spontaneous change in ST segment, and LP had significant values. In multivariate analysis, a spontaneous change in ST segment had the most significance (a relative hazard, 9.2; P = 0.036). Combined assessment of this index and other significant indices obtained higher positive predictive values (43–71%). Conclusions: A spontaneous change in ST segment is associated with the highest risk for subsequent events in subjects with a Brugada-type ECG. The presence of syncopal episodes, a history of familial sudden death, and/or LP may increase its value. [ABSTRACT FROM AUTHOR]

Late Potential in Brugada Syndrome. Introduction:Risk stratification for life-threatening arrhythmic events in Brugada syndrome is not yet established. The aim of the present study was to examine the usefulness of various markers in predicting life-threatening arrhythmic events in the Brugada syndrome.Methods and Results:Forty-six patients with Brugada-type ECGs were categorized into the symptomatic (n= 28) and asymptomatic (n= 18) groups. Statistical analyses were performed with respect to the usefulness of the following markers: SCN5A mutation, pharmacologic challenge, ventricular fibrillation (VF) inducibility by programmed electrical stimulation, and late potential (LP) by signal-averaged ECG (SAECG). Comparison between the two groups revealed a significant difference only in LP positivity (92.6% vs 47.1%, P= 0.0004). The symptomatic group had significantly lower RMS40, longer LAS40, and longer fQRSd compared with the asymptomatic group. A significant difference was noted, especially RMS40. The positive predictive value, negative predictive value, and predictive accuracy when setting a cutoff value of 15μV were 92.0%, 78.9%, and 86.4%, respectively. Furthermore, patients with an RMS40 value<15μV (n= 25) showed significantly higher rates of VF recurrence compared with patients with an RMS40 value≥ 15μV (n= 19, P= 0.047).Conclusion:Regarding risk stratification for identifying high-risk patients in Brugada syndrome, only LP by SAECG was shown to be useful, suggesting the importance of RMS40 in predicting the history of life-threatening arrhythmic events and the recurrence of VF.(J Cardiovasc Electrophysiol, Vol. 16, pp. 45-51, January 2005) [ABSTRACT FROM AUTHOR]

Electrocardiographic Assessment of AF. Introduction:This study evaluated the role of surface ECG in assessment of risk of new-onset atrial fibrillation (AF) after coronary artery bypass grafting surgery (CABG).Methods and Results:One hundred fifty-one patients (126 men and 25 women; age 65± 10 years) without a history of AF undergoing primary elective and isolated CABG were studied. Standard 12-lead ECGs and P wave signal-averaged ECG (PSAE) were recorded 24 hours before CABG using a MAC VU ECG recorder. In addition to routine ECG measurements, two P wave (P wave complexity ratio[pCR]; P wave morphology dispersion[PMD]) and six T wave morphology descriptors (total cosine R to T[TCRT]; T wave morphology dispersion of ascending and descending part of the T wave[aTMD and dTMD], and others), and three PSAE indices (filtered P wave duration[PD]; root mean square voltage of terminal 20 msec of averaged P wave[RMS20]; and integral of P wave[Pi]) were investigated. During a mean hospital stay of 7.3± 6.2 days after CABG, 40 (26%) patients developed AF (AF group) and 111 remained AF-free (no AF group). AF patients were older (69± 9 years vs 64± 10 years, P= 0.005). PD (135± 9 msec vs 133± 12 msec, P= NS) and RMS20 (4.5± 1.7μV vs 4.0± 1.6μV, P= NS) in AF were similar to that in no AF, whereas Pi was significantly increased in AF (757± 230μVmsec vs 659± 206μVmsec, P= 0.007). Both pCR (32± 11 vs 27± 10) and PMD (31.5± 14.0 vs 26.4± 12.3) were significantly greater in AF (P= 0.012 and 0.048, respectively). TCRT (0.028± 0.596 vs 0.310± 0.542, P= 0.009) and dTMD (0.63± 0.03 vs 0.64± 0.02, P= 0.004) were significantly reduced in AF compared with no AF. Measurements of aTMD and three other T wave descriptors were similar in AF and no AF. Significant variables by univariate analysis, including advanced age (P= 0.014), impaired left ventricular function (P= 0.02), greater Pi (P= 0.012), and lower TCRT (P= 0.007) or dTMD, were entered into multiple logistic regression models. Increased Pi (P= 0.038), reduced TCRT (P= 0.040), and lower dTMD (P= 0.014) predicted AF after CABG independently. In patients<70 years, a linear combination of increased pCR and lower TCRT separated AF and no AF with a sensitivity of 74% and specificity of 62% (P= 0.005).Conclusion:ECG assessment identifies patients vulnerable to AF after CABG. Combination of ECG parameters assessed preoperatively may play an important role in predicting new-onset AF after CABG.(J Cardiovasc Electrophysiol, Vol. 15, pp. 1-8, December 2004) [ABSTRACT FROM AUTHOR]

ARVD/C Misdiagnosis. Introduction: Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) has major implications for the management of patients and their first-degree relatives. Diagnosis is based on a set of criteria proposed by the International Task Force for Cardiomyopathies. We report our experience in providing a re-evaluation for patients who previously have been diagnosed with ARVD/C. Methods and Results: We studied 89 patients who requested a re-evaluation for diagnosis of ARVD/C at our center. Each of these patients had been diagnosed with ARVD/C at their initial evaluation. Each patient was re-evaluated with clinical history, physical examination, and noninvasive testing at our center. Invasive testing, which included electrophysiologic testing, right ventricular angiography, and endomyocardial biopsy, was performed when clinically indicated. Sixty (92%) of the 65 patients who had undergone magnetic resonance imaging (MRI) at an outside institution were reported to have an abnormal MRI consistent with ARVD/C. Among these patients, the only abnormality identified was the qualitative finding of intramyocardial fat/wall thinning in 46 patients. On re-evaluation, these qualitative findings were not confirmed. None of these 46 patients ultimately were diagnosed with ARVD/C. Among the entire patient group, only 24 (27%) of the 89 patients met the Task Force criteria for ARVD/C. Conclusion: This study demonstrates that the high frequency of “misdiagnosis” of ARVD/C is due to over-reliance on the presence of intramyocardial fat/wall thinning on MRI, incomplete diagnostic testing, and lack of awareness of the Task Force criteria. Diagnosis of ARVD/C cannot rely solely upon qualitative features on MRI. (J Cardiovasc Electrophysiol, Vol. 15, pp. 300-306, March 2004) [ABSTRACT FROM AUTHOR]

: ObjectivesWe sought to ascertain the prevalence and mode of expression of familial disease in a consecutive series of patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D).: BackgroundAutosomal-dominant inheritance is recognized in ARVC. The prevalence and mode of expression of familial disease in consecutive, unselected families is uncertain.: MethodsFirst- and second-degree relatives of 67 ARVC index patients underwent cardiac evaluation with history and examination, 12-lead and signal-averaged electrocardiogram (ECG), two-dimensional and Doppler echocardiography, metabolic exercise testing and Holter monitoring. Diagnoses were made in accordance with published criteria.: ResultsOf 298 relatives, 29 (10%; mean age 37.4 ± 16.4 years) had ARVC. These were from 19 of the 67 families, representing familial involvement in 28%. Of these affected relatives, 72% were asymptomatic, 17% had ventricular tachycardia (sustained VT 10%, nonsustained VT 7%) and 21% had left ventricular involvement. A further 32 relatives (11%; 37.7 ± 12.4 years) exhibited nondiagnostic ECG, echocardiographic or Holter abnormalities. Fifteen of these relatives were from families with only the proband affected, and inclusion of this subset of relatives would have resulted in familial ARVC in 48% of index cases. Four additional relatives (1% to 3%) fulfilled diagnostic criteria for dilated cardiomyopathy without any features of right ventricular disease.: ConclusionBy using current diagnostic criteria, familial disease was present in 28% of index patients. A further 11% of their relatives had minor cardiac abnormalities, which, in the context of a disease whose mode of inheritance is autosomal dominant, are likely to represent early or mild disease expression. We advocate that the current ARVC diagnostic criteria are modified to reflect the broader spectrum of disease that is observed in family members. [Copyright &y& Elsevier]

: ObjectivesWe sought to establish the role of genetic screening for ryanodine receptor type 2 (RyR2) gene mutations in families with effort-induced polymorphic ventricular arrhythmia (PVA), syncope and juvenile sudden death.: BackgroundThe RyR2 mutations have been associated with PVA, syncope and sudden death in response to physical or emotional stress.: MethodsWe studied 81 subjects (39 males and 42 females; mean age 31 ± 20 years) belonging to eight families with pathogenic RyR2 mutations. All subjects underwent screening for RyR2 mutations, electrocardiography (ECG), 24-h Holter monitoring, signal-averaged electrocardiography (SAECG), two-dimensional echocardiography and exercise stress testing. Electrophysiologic (EP) study was performed in nine patients.: ResultsSix different RyR2 mutations were found in eight families. Forty-three family members carried the gene mutation. Of these, 28 (65%) showed effort-induced arrhythmic symptoms or signs and one died suddenly during follow-up. Family history revealed 19 juvenile cases of sudden death during effort or emotion. In two families sharing the same mutation, no subject presented with PVA during the stress test; thus, sudden death and syncope were the only clinical manifestations. The 12-lead ECG was normal in all but two subjects, whereas five patients showed positive late potentials on the SAECG. In 17 (39.5%) of 43 subjects, the two-dimensional echocardiogram revealed localized kinetic abnormalities and mild structural alterations of the right ventricle. The EP study was not able to induce PVA.: ConclusionsThe absence of symptoms and PVA on the stress test in more than one-third of carriers of RyR2 mutations, as well as the lack of PVA inducibility by the EP study, underlies the importance of genetic screening for the early diagnosis of asymptomatic carriers and prevention of sudden death. [Copyright &y& Elsevier]

We review the contemporary understanding of the pathophysiology of repolarization alternans and present a perspective on the use of T-wave alternans (TWA) as a risk stratification marker of malignant ventricular arrhythmias. Several studies have demonstrated a high correlation of susceptibility to ventricular arrhythmias and sudden cardiac death with the existence of TWA. We describe a number of cellular and molecular alterations in the diseased heart that may provide a link between electrical and mechanical alternans and arrhythmia susceptibility. Repolarization alternans is likely the result of distinct and diverse cellular and molecular alterations that are associated with exaggerated regional repolarization heterogeneity, which renders the heart susceptible to malignant arrhythmias. [Copyright &y& Elsevier]

Although a relation between magnitude of ST segment elevation and myocardial damage has been shown in the early period of acute myocardial infarction (AMI), such a relation between the shape of the ST segment elevation, myocardial damage, and the clinical course remains obscure. For this purpose 62 first anterior AMI patients admitted in the first 6 h were enrolled for the study. On the basis of precordial V3 derivation prior to thrombolytic therapy, the shape of the ST elevation was separated into three groups: concave ( n = 26), straight ( n = 24), or convex types ( n = 12). The relation between the shape of the ST elevation recorded on admission, and the results of predischarge low-dose dobutamine stress echocardiography (LDE) performed ( n = 53) and signal-averaged ECG values were investigated. The basal wall motion score index (WMSI) and response to LDE in the concave group were better in the infarct zone. Additionally, the average akinetic segment number in the infarct zone was higher, and improvement in these segments was less in the convex and straight groups (concave 3.78 ± 2 vs 2.17 ± 2.1, P < 0.01; straight 5.15 ± 2.7 vs 4.45 ± 2.8, not significant (NS); convex 5.4 ± 2.3 vs 4.8 ± 2.1, NS; basal vs LDE). While only 13% (3/23) of the patients did not respond to LDE ( P < 0.05 vs group B and P < 0.01 vs group C), 35% (7/20) of group B and 60% (6/10) of group C patients did not respond to LDE. Although no relation was found between better left ventricular function (WMSI < 2) and shape of the ST elevation in basal evaluation by multiple logistic regression analysis ( P = 0.06), an independent relation was found between them following LDE ( P = 0.01, odds ratio (OR) 4.5, 95% Confidence Interval (CI) 1.3–14.7). The incidence of ventricular late potential (LP) positivity was 11% (3/26) in the concave group, 16% (4/24) in the straight group, and 58% (7/12) in the convex group ( P < 0.001 vs concave and P < 0.05 vs straight groups). We found that shape of the ST elevation could significantly predict the presence of late potentials in multiple logistic regression analysis ( P = 0.003, OR 10.7, 95% CI 2.2–51.7). There was no in-hospital death in the concave group, whereas five patients died in either the straight or the convex group. Furthermore, arrhythmia was lower in the concave group during this period ( P < 0.05), and exercise capacity was lower. In conclusion, we determined that there was a higher viable myocardium, and lower LP(positivity) and in-hospital mortality in patients with concave ST elevation on admission. [ABSTRACT FROM AUTHOR]

Abstract Background : The aim of the present study was to investigate the detection of anthracycline cardiotoxicity by signal-averaged electrocardiography (SAE) in children with cancer. Methods : There were 29 patients with a cumulative anthracycline (ATC) dose of 75-600 mg/m2 . None of them had congestive heart failure. Patients underwent SAE just before (detection of chronic cardiotoxicity) and just after (detection of acute cardiotoxicity) ATC therapy. Echocardiography and Holter electrocardi­o­graphy were performed at the same time. The rates of abnormal SAE, echocardiography, and electrocardiogram findings were calculated and compared for every 100 mg/m2 of ATC. Results : The SAE showed a significantly higher detection rate for acute cardiotoxicity was at a cumulative ATC dose of less than 400 mg/m2 when compared with other methods (P < 0.05). The lowest dose at which acute cardiotoxicy was detected by SAE was 117.3 mg/m2 . The detection of chronic cardiotoxicity by SAE was significantly higher at a cumulative ATC dose of 100-400 mg/m2 when compared with other methods (P < 0.05), and the lowest value showing toxicity was 373.3 mg/m2 . The lowest ATC dose causing chronic cardiotoxicity was significantly lower in patients less than 2-years-old (120.0 ± 28.3 mg/m2 ) than in the other age groups (P < 0.05). Conclusions : Acute and chronic ATC cardiotoxicity were detected by SAE at lower cumulative doses compared with other methods. The technique of SAE was a potentially useful method for detection of cardiotoxicity among those investigated and it provides useful information on subclinical cardiac dysfunction in patients receiving ATC therapy. [ABSTRACT FROM AUTHOR]

Introduction: The incidence of sudden death or ventricular fibrillation (VF) in asymptomatic Brugada syndrome patients with a family history of sudden death is reported to be very high. However, there are few reports on the prognosis of asymptomatic Brugada syndrome patients without a family history of sudden death. Methods and Results: Eleven patients (all male; mean age 40.5 ± 9.6 years, range 26 to 56) with asymptomatic Brugada-type ECG who had no family history of sudden death were evaluated. The degrees of ST segment elevation and conduction delay on signal-averaged ECG (SAECG) before and after pilsicainide were evaluated in all 11 patients. VE inducibility by ventricular electrical stimulation also was evaluated in 8 of 11 patients. Patients were followed for a period of 9 to 84 months (mean 42.5 ± 21.6). The J point level was increased (V1: 0.19 ± 0.09 mV to 0.36 ± 0.23 mV; V2: 0.31 ± 0.12 mV to 0.67 ± 0.35 mV) by pilsicainide. Conduction delay was increased (total QRS: 112.2 ± 6.3 msec to 131.7 ± 6.3 msec; under 40 µV: 42.0 ± 8.5 msec to 52.7 ± 12.7 msec; last 40 msec: 17.4 ± 5.9 µV to 10.4 ± 6.1 µV) on SAECG by pilsicainide. VF was induced in only 1 of 8 patients. None of the patients had syncope or sudden death during a mean follow-up of 42.5 ± 21.6 months. Conclusion: This study suggests that asymptomatic patients with Brugada-type ECG who have no family history of sudden death have a relatively benign clinical course. [ABSTRACT FROM AUTHOR]

We have applied various methods to extract parameters from high-resolution magnetocardiographic (MCG) and electrocardiographic (ECG) recordings for characterizing the risk of life-threatening arrhythmias. The methods include detection of late fields and late potentials at the end of the QRS, abnormalities in spectral variability and signal fragmentation during the QRS, and variability in the heart rate. In addition, we have developed methods to convert MCG signals measured with any sensor configurations to a common presentation form. The signal processing methods have been implemented on a user-friendly interface which allows fast and easy use in a clinical environment. [ABSTRACT FROM AUTHOR]

Introduction: Magnetocardiographic (MCG) mapping is a new method to record cardiac signals. This study examined the association of MCG late fields with the propensity to sustained ventricular tachycardia (VT) after myocardial infarction (MI). Methods and Results: One hundred patients with remote MI were studied, 38 with and 62 without history of VT. High-resolution MCG and signal-averaged ECG (SAECG) as a comparative method were recorded. Time-domain parameters describing the abnormal low-amplitude end QRS activity, MCG late fields, and SAECG late potentials were analyzed. Late field parameters differed significantly between the patient groups: filtered QRS duration was 137 ± 26 msec in the VT group and 110 ± 18 msec in the control group (P < 0.001), and root mean square amplitude of the last 40 msec was 260 ± 170 and 510 ± 360 fT (P < 0.001), respectively. The optimal MCG parameter combination yielded a sensitivity of 92% and a specificity of 61% in classification to the VT group, whereas those for SAECG were 63% and 66%. In a subgroup of 63 patients with marked left ventricular dysfunction and comparable stage of coronary heart disease, only MCG (sensitivity 73%, specificity 67%) but not SAECG could assign a patient to the VT group. Conclusion: Late fields of the MCG QRS complex indicate propensity to life-threatening arrhythmias in post-MI patients. This discriminative ability persists in the presence of severe left ventricular dysfunction where ECG late potentials lose their informative value. MCG late field analysis is a potential new method for noninvasive risk assessment in post-Ml patients. [ABSTRACT FROM AUTHOR]

Although atrial signal-averaged electrocardiogram (SAECG) has been proposed for noninvasive identification of patients with atrial tachyarrhythmias, the substantial variability of the measurement limits the clinical value. The aim of the study was to assess the short- to long-term reproducibiiity of atrial SAECG and to compare it to that of the conventional ventricular SAECG in 51 healthy volunteers (30 men; age 32 ±8 years]. In each subject, SAECG recordings were obtained using MAC-VU electrocardiograph and HiRES and PHiRES software (Marquette Medical Systems) and repeated after 5 minutes, 1 day, 1 week, and 1 month. Automatically detected onset and offset of the filtered QRS complex and P wave were subsequently corrected by two independent observers, and the averaged values were used for the analysis. Conventional ventricular SAECG parameters: filtered QRS duration (QRStot), low amplitude signal duration, and root mean square voltage (RMS) of the terminal 40 ms of QRS; and 5 atrial parameters: filtered P wave duration (Ptot), RMS of the terminal 40, 30, 20 ms, and of the entire P wave were obtained. Relative errors of different pairs of measures were used to assess the intrasubject reproducibility. QRStotand Ptot were the most reproducible parameters. The relative errors after 5 minutes, 1 day, 1 week, and 1 month were 0.8% to 2.4% for QRStot, and 1.3% to 4.2% for Ptot. For RMS voltages, the relative errors exceeded 15% in short-term and 20% in long-term recordings. Although Ptot was statistically less reproducible than QRStot, the reproducibility of the former was good and comparable to that of the QRStot. The reproducibility of the voltage parameters was significantly poorer than that of the duration parameters. The study showed a satisfactory short- and long-term reproducibility of Ptot in the atrial SAECG in healthy subjects. However, low reproducibility of the voltage parameters should be considered in clinical applications. [ABSTRACT FROM AUTHOR]

Studies the relationship between the signal-averaged electrocardiogram and electrophysiologic testing. Correlation of signal-averaged electrocardiographic determination of late potentials with prior or induced sustained ventricular tachycardia; Significant value in identifying patients with prior clinical ventricular tachycardia; Correlation of late potentials with ventricular tachycardia.