Signal-averaged ECG Parameters Research Articles

Blood lipid profile and signal averaged ECG parameters in patients with hystory of myocardial infarction

Blood lipid profile and signal averaged ECG parameters in patients with hystory of myocardial infarction

New parameter of the second part of the P-wave predict atrial fibrillation: comparison with P-wave signal-averaged electrocardiography

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): Kyung Hee University Background A study to predict the risk of AF by analyzing the P-wave of the electrocardiogram in detail has been attempted for a long time, and P-wave signal-averaged ECG is also known to be helpful. Recently, the P-wave was analyzed by dividing it into two parts, and when the latter part is extended, it suggests left atrium dilatation or delayed conduction, and it is suggested that this may be a slightly more sensitive parameter. Objective The purpose of this study was to find the best predictor of atrial fibrillation by comparing the characteristics of the P-wave in the subjects with AF and healthy controls using 12-lead ECG and signal-averaged ECG (SAECG). Methods We recruited 58 paroxysmal atrial fibrillation patients in AF group and 57 people in the control group. All subjects underwent 12-lead ECG, P-wave signal-averaged ECG, and transthoracic echocardiography. The total P-wave duration (PWD), the second part of the P-wave were measured with an electronic caliper in lead II. Results The second part of the P-wave was higher in the AF group, which was statistically significant (70.8 ± 20.6 vs. 60.5 ± 12.3ms, respectively, p<0.01). Filtered PWD and the integral of the P-wave were significantly higher in the AF group. The second part of the P-wave, filtered PWD, and the integral of P-wave were univariate and multivariate predictors of AF. The second part of the P-wave showed ROC (Receiver operating characteristic curves) area of 0.635, and the cut-off value was 61.5ms with 59.6% sensitivity and 59.6% of specificity. Of the SAECG parameters, the longer filtered PWD predicted a history of AF with an AUC (Area under the ROC curve) of 0.669. Conclusions We confirmed that second part of the P-wave which reflects the electrophysiological status of the left atrium is a valuable marker for predicting AF. Also, Filtered PWD and the integral of the P-wave among the SAECG parameters were useful predictors of AF.

PO-02-228 ASSOCIATION BETWEEN SIGNAL-AVERAGED ECG INDICES AND RV STRUCTURAL ABNORMALITIES IN PATIENTS WITH ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY: INSIGHTS FROM NORDIC ARVC REGISTER

The value of signal-averaged ECG (SAECG) derived ventricular late potentials (LP) as a minor depolarization criterion of arrhythmogenic right ventricular cardiomyopathy (ARVC) has been debated. Another criterion from the same category, terminal activation duration (TAD>55 ms), is obtained from standard V1 ECG lead, which makes it easier for use. However little data exist regarding the relationship between structural right ventricular (RV) ARVC substrate, LP and TAD. We aimed to explore the association between structural and functional RV abnormalities assessed using cardiac magnetic resonance (CMR), SAECG parameters, and abnormal TAD. Patients with definite ARVC diagnosis or genotype-positive family members who were recruited in the Nordic ARVC Registry with SAECG and CMR were included (n=268, mean age 42±16 years, female 46%, probands 49%). RV end-diastolic volume index (RVEDVI), RV ejection fraction (RVEF), and late gadolinium enhancement (LGE) presence were assessed. RV was defined as enlarged if RVEDVI > 100 ml/m2 for men and 90 ml/m2 for women. RVEF was considered reduced if lower than 45%. SAECG components were assessed using TFC2010 definitions: filtered QRS duration (fQRSd)>114 ms, duration of terminal low-amplitude QRS signal below 40 μV (LAS40)> 38 ms and root-mean-square voltage of the terminal 40 ms (RMS40)< 20 μV. An abnormal value of any one or more of these indexes was considered as the presence of LP. We assessed sensitivity and specificity of the SAECG indexes and TAD for association with abnormal RVEF, LGE and/or RVEDVI. C-statistics was used to assess the association between each of SAECG parameters as continuous variables and RV abnormalities. All 3 SAECG indexes were significantly associated with RV structural abnormalities using c-statistics (Table), each of them characterized by higher specificity and lower sensitivity than LP. TAD demonstrated high specificity but poor sensitivity in prediction of RV structural abnormalities. LP had lower specificity, but much higher sensitivity for association with RV structural and functional abnormalities than TAD. In a large cohort of patients with definite ARVC or genotype-positive family members SAECG indexes appear to have lower specificity for detection of structural and functional RV abnormalities compared to TAD, however its sensitivity far exceeds the one of the TAD and supports SAECG value as an ECG indicator of RV substrate.

SAECG - advances in Brugada stratification

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Brugada syndrome (BrS) is a relevant cause of sudden cardiac death (SCD) in young adults. Several risk factors have been identified, but clinical decision making remains extremely challenging, particularly in asymptomatic patients. Purpose To explore the usefulness of the non-invasive assessment of late potentials (LPs) based signal-averaged ECG (SAECG) for risk stratification in BrS. Methods Prospective single-center study of patients with BrS included from 2003 to 2021. LPs were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component of the terminal portion of the QRS (LAS40) in conventional and modified right precordial leads. The primary endpoint was the occurrence of malignant arrhythmic events (MAEs), defined as a composite of SCD or appropriate shocks. Uni- and multivariate Cox regression survival analyses were used to identify significant prognostic predictors considering the clinical, genetic, and electrocardiographic characteristics as well as the tercile distribution of the SAECG parameters. A risk score was computed incorporating the significant LPs variables and its usefulness for prognostic stratification was explored using Kaplan Meier survival analysis. Results Our cohort consisted of 117 patients (mean age: 47±13 years, 33% male), including 75 (65%) with type 1 spontaneous pattern and 92 (79%) asymptomatic individuals. Symptoms at presentation included syncope in 16 pts (14%) and polymorphic VT/cardiac arrest in 4 (3.4%). During a median follow-up of 4.1±0.3 years, 8 pts (6.8%) suffered MAEs: 3 (2.6%) with SCD and 5 (4.3%) with appropriate shocks. The risk of events differed in relation to the several SAECG parameters (Table 1), increasing linearly with the fQRS duration determined either in the conventional (HR 1.03, 95% CI 1.01-1.06, p=0.008) or modified leads (HR: 1.03, 95% CI 1.01- 1.05, p=0.003). The SAECG score incorporated as risk markers a fQRS ≥113ms and a RMS40 &amp;lt;13 μV. Patients with both risk markers presented a 7-fold increased risk (HR 7.17, 95% CI 1.29-40, p = 0.025), independently of the baseline symptomatic status and ECG pattern. Conclusion This study shows that the non-invasive assessment of LPs based on SAECG is useful for prognostic stratification of BrS. It was possible to identify a subset of patients presenting a high risk of events who may deserve individualized preventive strategies.

Diagnosing arrhythmogenic ventricular cardiomyopathy: a re-appraisal of the role and normal range of the signal-averaged ECG

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The 2010 Task Force Criteria (TFC) for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (A(R)VC) in 1st degree relatives includes an abnormality in a single parameter of the signal averaged ECG (SAECG). SAECG normal ranges were derived predominately from ischaemic heart disease patients, so may not be applicable in an A(R)VC population. There remain concerns that the SAECG is not specific enough and its role in the diagnosis of A(R)VC is under scrutiny. Purpose to improve the diagnostic utility of the SAECG Methods Patients with an A(R)VC diagnosis and 1st degree family members (FM) under follow-up at a single inherited cardiac conditions (ICC) centre were included. All cases were independently reviewed by 3 cardiologists experienced in the diagnosis and management of A(R)VC. All SAECGs included were free from artefact. TFC clinical variables and genetic status were recorded for each patient. Where tests had been repeated the most recent values were used. Because of concerns about the use of a single abnormal SAECG parameter in making a clinical diagnosis we required ≥2 abnormal SAECG parameters, or a confirmed genetic mutation to make a diagnosis. A diagnosis of false positive SAECG was made with ≥2 abnormalities when the individual was known not to carry the familial pathogenic mutation. Results A study population of 160 patients (male 103 (64%), age 46yrs (range 18-85yrs); 41 pro-bands and 119 FM. 62(52%) FM had a clinical diagnosis of AVC, with ARVC the pre-dominant phenotype 51(82%). A pathogenic genetic variant was identified in 24(47%) of FM with ARVC. The SAECG data is presented graphically for each parameter. A clinical diagnosis of ARVC was made on the basis of an affected 1st degree FM and an abnormal SAECG in 24(47%) of FM. Of these, 16(67%) had three abnormal SAECG parameters, 6(25%) two and 2(8%) a single abnormal parameter. Both patients with only one abnormal SAECG parameter carry a pathogenic variant. In total 88% of FM with ARVC, and 32% of FM without AVC had an abnormal SAECG as per current TFC. False positive values were mainly in fQRS duration (17/18), but also LAS40 (5/18), and RMS40 (2/18). By redefining an abnormal fQRS duration to be ≥118ms, false positives are reduced from 17 to 4. In addition, if there is a requirement for a 2nd abnormality then the false positives are reduced to 2 (4%). By adjusting the diagnostic criteria to fQRS duration ≥118ms, with a 2nd abnormal parameter or known pathogenic gene carrier status none of the 24 FM with a clinical diagnosis on abnormal SAECG alone would change diagnostic classification. Conclusion The SAECG is useful in family screening as it is frequently the only test to show an abnormality. However, the current TFC reference values lack specificity. By redefining an abnormal fQRS as ≥118ms with the requirement of a 2nd abnormal parameter, specificity is increased to 96%, with no significant change in sensitivity. Abstract Figure. SAECG Parameters in Family Members

Development of AI-based method to detect the subtle ECG deviations from the population ECG norm

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Academy of Science of Ukraine Background Electrocardiogram (ECG) is still the primary source for the diagnostic and prognostic information about cardiovascular diseases. The concept of "normal ECG" parameters is crucial for the reliable diagnosis, since it provides reference for the ECG under examination. With the development of new methods and tools for ECG feature extraction and classification based on artificial intelligence (AI), it becomes possible to identify subtle changes in the heart activity to detect possible abnormalities at the early stage. The challenge of this work is to identify the deviations in ECG of clinically healthy persons from the conditional "population" norm . Methods The normal ECG is described as a feature vector composed of the time-magnitude parameters of signal-averaged ECG (SAECG). To define the subjects that possibly have variations from the "population" norm, the outlier detection approach is proposed: first the cloud of the vectors , constructed from the set of normal ECG"s , obtained from young, clinically similar healthy persons was created in feature space. Then, a particular ECG is considered deviant and requires the attention of the clinician when it is considered an outlier of the cloud of normal ECGs. In the experiment, SAECGs from the group of 139 young subjects (male, age 18-28 years) with no reported cardiovascular problems are used to extract 34 features from SAECG leads (magnitudes and durations of ECG waves, duration of ECG segments, etc.). ECGs were routinely previewed by qualified physicians, and no obvious anomalies were noticed. The Isolation Forest anomaly detection method is used with variable numbers of trees and different contamination parameters. Results The ratio of outliers were changed from 5 to 10% (7-12 subjects) with various numbers of estimator trees. Seven outlier SAECGs were repeatedly appearing for various settings. Out of these, 4 subjects were the oldest persons in group examined , and 3 others had a rare ventricular premature beats during routine ECG examination. Conclusion The proposed method is promising for application in routine and express ECG tests since it is able to quantify the subtle deviations from the normal ECG group.

SAT-058 Signal-averaged ECG abnormality and mortality in hemodialysis patients: A prospective study

Cardiovascular disease is a major cause of death in hemodialysis patients. Simple, non-invasive cardiac investigations such as signal-averaged ECG (SAECG) and other measured ECG parameters have been used in the general population and coronary disease to stratify risk of all-cause mortality. This study aims to investigate the association between abnormal ECG and SAECG parameters and all-cause mortality in maintenance hemodialysis patients.

The application of signal average ECG in the prediction of recurrences after catheter ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy

BackgroundThe changes of signal averaged ECG (SAECG) in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) undergoing radiofrequency catheter ablation (RFCA) of ventricular arrhythmias (VAs) remains unknown. MethodsBetween 2010 and 2014, a total of 81 ARVD/C patients underwent endocardial and/or epicardial RFCA for drug-refractory VAs. Seventy patients (mean age 46.2±14.1years, 37 males) achieving acute procedure success (negative inducibility) were enrolled. Baseline characteristics, non-invasive examinations and SAECG (before and 3months after RFCA) were collected retrospectively. ResultsAfter successful RFCA, the electrical parameters of SAECG changed in 39 patients (55.7%), including 28 patients (40%) with electrical regression (group 1), and 11 patients (15.7%) with electrical progression (group 3). Thirty-one patients (44.3%) showed no significant SAECG change (group 2). During a mean follow-up of 17.8±10.7months, 23 patients (32.9%) had VA recurrences, including 4 in group 1, 12 in group 2, and 7 in group 3. In comparisons with groups 2 and 3, group 1 patients had a significantly better VA recurrence-free survival (P=0.02). In multivariable Cox regression analysis, electrical regression was found to be associated with fewer VA recurrences (P=0.02, OR: 0.28, 95% CI: 0.10–0.83). ConclusionsElectrical regression of SAECG after RFCA in ARVD/C was found to be associated with fewer VA recurrences.

P Wave Signal-Averaged Electrocardiography in Patients with Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is associated with higher incidence of supraventricular arrhythmias. Atrial late potentials (ALP) detected by P-wave signal-averaged electrocardiography (SAECG) could be useful in detecting the patients at risk for supraventricular arrhythmias. Our objective was to assess the role of P-wave SAECG and ALP detection for arrhythmic risk evaluation of the patients with exacerbated COPD. We prospectively included 45 patients with exacerbation of COPD and 58 age- matched patients with no history of pulmonary disease in a control group. We performed pulmonary function tests, arterial blood gases, echocardiography, 24-hour Holter monitoring and P-wave SAECG. We measured filtered P-wave duration (FPD), the root mean square (RMS) voltages in the last 40, 30 and 20 ms of the filtered P-wave (RMS 40, RMS 30 and RMS 20), the root mean square voltage of the filtered P-wave potentials (RMS-p), and the integral of the potentials during the filtered P-wave (Integral-p). ALP was defined as FPD > 132 ms and RMS 20 < 2.3 μV. Isolated atrial premature beats (APB) and supraventricular tachycardias (SVT) were more frequent in the COPD group. There were no significant differences between groups regarding the P wave SAECG parameters. In the COPD group none of the supraventricular arrhythmias was correlated with ALP or any P-wave SAECG parameters. The patients with acute exacerbation of COPD but no apparent cardiac disease have a higher incidence of supraventricular arrhythmias. P-wave SAECG analysis and ALP detection have little value in the arrhythmic risk evaluation of these patients.

Clinical Differentiation Between Physiological Remodeling and Arrhythmogenic Right Ventricular Cardiomyopathy in Athletes With Marked Electrocardiographic Repolarization Anomalies

BackgroundPhysiological cardiac adaptation to regular exercise, including biventricular dilation and T-wave inversion (TWI), may create diagnostic overlap with arrhythmogenic right ventricular cardiomyopathy (ARVC). ObjectivesThe goal of this study was to assess the accuracy of diagnostic criteria for ARVC when applied to athletes exhibiting electrocardiographic TWI and to identify discriminators between physiology and disease. MethodsThe study population consisted of athletes with TWI (n = 45), athletes without TWI (n = 35), and ARVC patients (n = 35). Subjects underwent electrocardiography (ECG), signal-averaged electrocardiography (SAECG), echocardiography, cardiac magnetic resonance imaging (CMRI), Holter monitoring, and exercise testing. ResultsThere were no electrical, structural, or functional cardiac differences between athletes exhibiting TWI and athletes without TWI. When athletes were compared with ARVC patients, markers of physiological remodeling included early repolarization, biphasic TWI, voltage criteria for right ventricular (RV) or left ventricular hypertrophy, and symmetrical cardiac enlargement. Indicators of RV pathology included the following: syncope; Q waves or precordial QRS amplitudes <1.8 mV; 3 abnormal SAECG parameters; delayed gadolinium enhancement, RV ejection fraction ≤45%, or wall motion abnormalities at CMRI; >1,000 ventricular extrasystoles (or >500 non-RV outflow tract) per 24 h; and symptoms, ventricular tachyarrhythmias, or attenuated blood pressure response during exercise. Nonspecific parameters included the following: prolonged QRS terminal activation; ≤2 abnormal SAECG parameters; RV dilation without wall motion abnormalities; RV outflow tract ectopy; and exercise-induced T-wave pseudonormalization. ConclusionsTWI and balanced biventricular dilation are likely to represent benign manifestations of training in asymptomatic athletes without relevant family history. Diagnostic criteria for ARVC are nonspecific in such individuals. Comprehensive testing using widely available techniques can effectively differentiate borderline cases.

Role of signal-averaged electrocardiography and ventricular late potentials in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiac arrhythmias. Ventricular late potentials (VLP) on signal-averaged electrocardiography (SAECG) are associated with an increased risk for malignant ventricular arrhythmias. Our aim is to investigate the modifications of SAECG parameters and the presence of VLP as possible indicators of proarrhythmic substrate in patients with COPD. We prospectively enrolled 41 consecutive patients in the COPD group and 63 patients without any history of pulmonary disease, matched for age and hypertension history, in the control group. Pulmonary function tests, arterial blood gases, echocardiography, 24-hour Holter monitoring and SAECG were performed. We measured total filtered QRS duration (QRSf), duration of high frequency, low-amplitude signals < 40 V (HFLA40), and root mean square voltage in the last 40 ms (RMS40). VLP were considered if at least two of these parameters were abnormal. Results. We did not register any significant differences in QRSf, HFLA40 or RMS40 between the two groups. In the COPD group there was a non-significant higher percentage of patients with VLP in comparison with the control group. In the COPD patients we registered a significantly higher number of isolated premature ventricular beats and of combined complex ventricular arrhythmias, consisting of polymorphic PVC, couplets, triplets or nonsustained ventricular tachycardias. None of these arrhythmic parameters correlated with SAECG variables or with the presence of VLP. Conclusion. In COPD patients parameters measured on signal-averaged electrocardiography and ventricular late potentials analysis have little value in risk stratification for ventricular arrhythmias.

Relationship between echocardiographic right-ventricular dimensions and signal-averaged electrocardiogram abnormalities in endurance athletes.

Regular physical exercise results in physiological cardiovascular changes. Athletes may demonstrate electrocardiographic changes that can also be seen in certain cardiomyopathies such as arrhythmogenic right-ventricular cardiomyopathy (ARVC). The aim of this study was to assess the prevalence of one such electrocardiographic characteristic, the abnormal signal-averaged ECG (SAECG), and to assess the correlation between SAECG parameters and echocardiographic parameters in athletes participating in sporting disciplines with combined strength and endurance components. We evaluated 24 elite athletes and 27 amateur athletes participating in combined high dynamic and high static (HDHS) sports, using an ECG, SAECG, and a transthoracic echocardiogram. The SAECG was regarded as positive for late potentials if one out of three parameters was abnormal. Prolongation of the filtered QRS duration (fQRS) was present in all of the elite athletes, compared with 74.1% of the amateur athletes (P = 0.011). There was a low prevalence of abnormalities in the other two SAECG parameters [low-amplitude signal (LAS) duration and root-mean-square (RMS) voltage]. The percentage of elite athletes and amateur athletes with ≥2 abnormal SAECG parameters was 8.3 and 7.4% (P = 0.99), respectively. Most of the echocardiographic dimensions were significantly greater in the elite athlete group compared with the amateur athletes. There was a moderate positive correlation between the fQRS and right-ventricular dimensions. The majority of elite and amateur athletes participating in HDHS sports reveal a prolonged fQRS duration on the SAECG, and according to the 2010 Task Force criteria for the diagnosis of ARVC, these athletes therefore demonstrate late potentials. The extent of fQRS prolongation is positively correlated with RV dimensions. Therefore SAECG findings should be interpreted with caution in endurance athletes.

Correlation Between Signal-Averaged ECG and the Histologic Evaluation of the Myocardial Substrate in Right Ventricular Outflow Tract Arrhythmias

The differential diagnosis between idiopathic and cardiomyopathy-related right ventricular outflow tract (RVOT) ventricular arrhythmias (VAs) is crucial. Signal-averaged ECG (SAECG) abnormalities are frequent in cardiomyopathy-related RVOT-VAs, although their pathophysiologic basis and diagnostic value in this setting are undefined. We tested the association between SAECG and the myocardial substrate underlying RVOT-VAs. Twenty-four consecutive patients (median age, 50 years [42-59]; 12 men) with RVOT-VAs (10 with frequent [>1000/24 hours] premature ventricular contractions, 14 with ventricular tachycardias) underwent SAECG with 40-Hz filtering and electroanatomic mapping (EAM) with EAM-guided biopsy for characterization of the RVOT-VAs substrate. A filtered averaged QRS (fQRS) was obtained and analyzed for fQRS duration, low amplitude signal duration<40 mV (LAS40), and root-mean-square voltage in the last 40 ms of the QRS (RMS40). Standard definition of EAM scar was used. EAM-guided biopsy diagnosed ARVC in 11 (46%), myocarditis in 8 (33%), and idiopathic RVOT-VAs in 5 (21%) patients. Patients with cardiomyopathy-related RVOT-VAs had ≥1 EAM scar (median, 2 [1-2]; all with RVOT scar). EAM of patients with idiopathic RVOT-VAs was normal. Patients with cardiomyopathy-related RVOT-VAs had significantly longer fQRS (106 ms [92-132] versus 83 ms [82-84], P=0.01) and LAS40 (39 ms [36-51] versus 19 ms [18-21], P=0.02), and lower RMS40 (18 µV [9-26] versus 33 µV [32-33], P=0.04). A significant linear correlation was found between the extension (cm2) of the RVOT scar and all 3 SAECG parameters (rs=0.76, P<0.001 for the fQRSd; rs=0.73, P<0.001 for the LAS40; and rs=-0.72, P<0.001 for the RMS40). Using the established 2 of 3 criteria (ie, late potentials), SAECG diagnosed cardiomyopathy-related RVOT-VAs with high positive (100%) but low negative (38%) predictive values and missed 7 of 9 (78%) patients with RVOT scar<8 cm2. In patients with RVOT-VAs, abnormal SAECG parameters reflect the presence of extensive cardiomyopathic involvement of the RVOT. However, a negative SAECG does not reliably rule out cardiomyopathy-related RVOT-VAs in the presence of a small RVOT scar.

Diuretic therapy effects on the signal-averaged ECG parameters of atrial complex and supraventricular arrhythmias in patients with coronary heart disease and chronic heart failure

Aim. To study the signal-averaged ECG (SA-ECG) parameters of atrial complex and supraventricular arrhythmias (SVA) in patients with coronary heart disease (CHD) and chronic heart failure (CHF), treated with diuretics (D) torasemide and furosemide. Material and methods. The study included 107 patients with CHD and CHF. All participants underwent 24-hour ECG monitoring and the registration of SA-ECG atrial complex parameters. In total, 52 patients received furosemide, and 55 were administered torasemide. Results. In both groups, D therapy was associated with some increase in the duration of filtered P and LAS5, as well as a decrease in RMS20. These changes were more pronounced in the furosemide-treated patients. Torasemide demonstrated better effects on the SVA dynamics, which manifested in the decreased numbers of single, paired, and grouped SV extrasystoles. Conclusion. In CHD and CHF patients, the disturbed atrial depolarisation was manifested in negative dynamics of SA-ECG atrial complex parameters. Torasemide therapy did not affect the atrial complex parameters and also reduced SVA incidence, which made torasemide a medication of choice for patients with CHD and CHF.

Diurnal Fluctuation of Late Potential as a Risk Factor in Brugada Syndrome Patients

Background: Diurnal fluctuation of late potential (LP) on signal averaged ECG (SAECG) as a risk factor remains unknown in Brugada syndrome (BS). Methods: This study comprised 24 BS patients. All the patients underwent SAECG and 24 hrs-SAECG monitoring which assessed every 3 hrs. The patients demonstrating type 1–2 BS ECG and LP underwent an electrophysiologic study (EPS). The coefficient of variation of parameters on 24 hrs-SAECG was determined as fluctuation index (FI). Results: The type 1, 2, and 3 BS pts were 8, 9, and 7 pts, respectively. LP was documented in 100, 33, and 29% for type 1, 2, and 3 pts, respectively (P<0.01). The parameters on 24 hrs-SAECG in high-risk group demonstrating type-1 ECG or type-2 ECG with both LP and VF induction (Group A N=8) were compared to those in low-risk group demonstrating type 2–3 ECG without VF induction (Group B N=16). Mean value of SAECG parameters significantly differed between Groups A and B (f-QRS: 152±9 vs. 141±11 ms, LAS40: 43±11 vs. 28±12 ms, RMS40: 15±7 vs. 42±23 µV P<.001). The daytime (6AM–6PM) FI was significant greater in Group A than in Group B (f-QRS: 4.7±1.9 vs. 2.4±1.0 p<.05, LAS40: 17.2±7.1 vs. 9.1±5.6 p<.05, RMS40: 34.5±19.3 vs. 15.0±8.7 P<.05). Meanwhile during nighttime (6PM–6AM) it did not differ between groups (NS). Conclusion: This study may indicate that the great daytime fluctuation of LP implies high-risk of BS and 24 hrs-SAECG leads to select high-risk BS patients.

Diagnostic Utility of Signal-Averaged Electrocardiography for Detection of Cardiac Sarcoidosis

Cardiac sarcoidosis (CS) occurs in up to 25% of patients with pulmonary involvement. Early diagnosis is critical because sudden death from ventricular arrhythmias can be the initial presentation. We sought to evaluate the diagnostic utility of signal-averaged ECG (SAECG) for detection of cardiac involvement of sarcoidosis. Subjects with biopsy proven sarcoidosis and symptoms suggestive of possible cardiac involvement were included in the cohort. Standard criteria for SAECG were used. Subjects were considered to have CS if they met criteria established by the Japanese Ministry of Health and Welfare modified to include cardiac MRI. Of the 88 patients in the cohort 27 had evidence of CS independent of the SAECG results. The SAECG was abnormal in 14 of these 27 patients and 11 of the 61 of the subjects without cardiac involvement (P < 0.01). The sensitivity of SAECG detection of CS was 52% with a specificity of 82%. For the entire cohort, SAECG had a positive predictive value (PPV) of 0.56 and a negative predictive value (NPV) of 0.79. Within a subgroup of 67 patients with an unfiltered QRS duration of <100 ms, the specificity for diagnosing cardiac sarcoidosis improves to 100% with a reduced sensitivity of 36.8. Of the SAECG parameters, LAS40 was significantly associated with the diagnosis of cardiac sarcoidosis for the entire cohort (P < 0.01) and among the subgroup of patients with an unfiltered QRS duration of <100 ms (P < 0.01). SAECG is a useful screening tool in the evaluation of sarcoidosis for detection of cardiac involvement.

Reconciling the Protean Manifestations of Arrhythmogenic Cardiomyopathy

Medical conception of a disease begins with in vivo observation and develops with recognition of cognate findings on gross anatomy, histology, and cellular pathology. It was histopathology that established myocyte disarray as the cardinal feature of hypertrophic cardiomyopathy, present even in cases where left ventricular (LV) hypertrophy is subtle or absent. To this day, clinical-pathological association retains its historical value as the primary means of gaining insight into underlying disease processes. Enhancing its appeal is its accessibility to physicians, most of whom are familiar with histopathology from medical school and attuned to visual diagnosis. Article see p 632 With the advent of molecular genetics, however, the limitations of clinical-pathological association have become apparent and nowhere more so than in the inherited arrhythmia syndromes. In the long-QT and Brugada syndromes and catecholaminergic polymorphic ventricular tachycardia, a structurally normal heart belies the propensity to ventricular arrhythmia and sudden cardiac death (SCD). How this might be possible began to unravel with the isolation of mutations in genes encoding ion channels, transporters, and binding proteins. Genetic studies also have provided fresh insights into diseases with an obvious pathological substrate, such as hypertrophic cardiomyopathy, in which sarcomeric mutations predominate. Families with a high incidence of SCD and myocyte disarray but minimal LV hypertrophy were found to have mutations in troponin T,1 lending further support to the inclusion of this phenotype within the spectrum of hypertrophic cardiomyopathy. Redefining diseases according to their genetic etiology, while attractive, is less straightforward than immediately obvious. Defects in sarcomeric components, for example, have been implicated in both hypertrophic cardiomyopathy and dilated cardiomyopathy. In some heritable disorders, such as dilated cardiomyopathy, marked locus heterogeneity precludes delineation of a single genetic determinant. The ultimate solution to disease classification involves going 1 step further and identifying a unifying molecular mechanism, which may …

Noninvasive Diagnosis of Electroanatomic Abnormalities in Arrhythmogenic Right Ventricular Cardiomyopathy

The diagnostic reliability and pathophysiologic relevance of different noninvasive diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) are undefined. We tested the association between noninvasive diagnostic criteria for ARVC and the presence of low-voltage areas (LVAs) detected at electroanatomic voltage mapping (EAM). Noninvasive diagnostic criteria, including ECG, signal-averaged ECG (SAECG), and cardiac magnetic resonance (CMR) criteria, were compared with the presence and location of LVAs detected at right ventricular (RV) EAM in 17 patients (9 men) aged 50 ± 16 years with biopsy specimen-proven ARVC. LVAs were found in 15 (88%) patients. Patients with surface ECG abnormalities showed a higher degree of RV involvement than those without ECG abnormalities (number of LVAs, 1.8 ± 0.5 versus 0.9 ± 0.6, respectively; P < 0.01). A significant association was found between SAECG abnormalities and LVAs in the RV outflow tract (P = 0.03) but not between SAECG parameters and LVAs in other RV regions. Among CMR findings, RV delayed enhancement was more significantly associated with the distribution of LVAs (free wall, P < 0.01; outflow tract, P < 0.01; posteroinferior wall, P = 0.02). Regional RV dysfunction also showed a good correlation with LVAs, with the most significant association being found with the free wall (P = 0.01), whereas RV fat infiltration at CMR was not correlated with LVAs. In patients with ARVC, SAECG abnormalities correlate with the presence of LVAs selectively in the RV outflow tract, whereas surface ECG abnormalities are associated with a more diffuse RV involvement. Myocardial delayed enhancement is the CMR finding more strongly associated with LVAs, thus supporting the appropriateness of its inclusion among diagnostic criteria for ARVC.

Signal-Averaged Electrocardiogram in Physically Healthy, Recently Abstinent Chronic Cocaine Users

: Cocaine use is associated with cardiac arrhythmias. Markers of ventricular late potentials, which may be a precursor to malignant ventricular arrhythmias, can be detected by signal-averaged electrocardiography (SA-ECG) but not by standard ECG. : We evaluated SA-ECG parameters in 60 medically screened, physically healthy, recently abstinent cocaine users (53 males, mean [SD] age, 34.0 [4.6] years; 10.1 [6.0] years of use) and 54 nondrug-using controls (21 males, mean [SD] age 28.4 [7.8] years). SA-ECGs were done periodically for ≤12 weeks of monitored abstinence in 25 cocaine users. We analyzed 3 SA-ECG parameters considered markers of ventricular late potentials: duration of filtered QRS complex, duration of low-amplitude potentials during terminal 40 ms of QRS complex (LAS40), and root mean square voltage during terminal 40 ms of QRS complex (RMS40). : Cocaine users differed significantly from controls in filtered QRS complex (118.5 [11.2] ms versus 111.9 [11.4] ms; P = 0.03) but not in LAS40 (28.9 [8.2] ms versus 30.8 [8.3] ms; P = 0.40) or RMS40 (40.0 [19.8] μV versus 30.2 [20.1] μV; P = 0.06) values. The proportion of subjects with abnormal SA-ECG parameters did not differ significantly between male cocaine users and male controls. There were no significant changes over time in either the mean values or proportion of subjects with abnormal values for any SA-ECG parameter. There were significant gender differences among controls but not among cocaine users. : These findings suggest that chronic cocaine use is not associated with a higher prevalence of abnormal SA-ECG parameters in physically healthy users.

Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) has evolved from postmortem pathology at to a diagnosable clinical condition, and holds promise for definitive genetic diagnosis. Its prevalence is between 1/1,000 and 1/5,000, with 10% of deaths occurring before age 19 and 50% before age 35. When analyzed against age-specific norms, the electrocardiography (ECG) and signal-averaged ECG (SAECG) have moderate sensitivity for ARVC. Endomyocardial biopsy in young individuals with ARVC demonstrates fibrosis more frequently than fatty infiltration, and is convincing for the diagnosis in approximately 1/3 (often in patients who would not otherwise be diagnosed), but has a recognized complication rate of 2%. Newer technologies of magnetic resonance imaging and voltage mapping hold promise but require further assessment in young individuals suspected to have ARVC. Genetic diagnosis of one of several desmosomal mutations is positive in an approximately 50% of suspected patients, and may provide clues to the pathophysiology of the disease. Serial studies of myocardial function, ambulatory electrocardiography, and SAECG parameters may be useful in risk stratification of identified patients, although their applicability to genetically identified asymptomatic individuals has not been studied.