Showing papers on "QRS complex published in 2012"

Effect of QRS duration and morphology on cardiac resynchronization therapy outcomes in mild heart failure: results from the Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) study.

Abstract: Background—Cardiac resynchronization therapy (CRT) decreases mortality, improves functional status, and induces reverse left ventricular remodeling in selected populations with heart failure. We aimed to assess the impact of baseline QRS duration and morphology and the change in QRS duration with pacing on CRT outcomes in mild heart failure. Methods and Results—Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction (REVERSE) was a multicenter randomized trial of CRT among 610 patients with mild heart failure. Baseline and CRT-paced QRS durations and baseline QRS morphology were evaluated by blinded core laboratories. The mean baseline QRS duration was 151±23 milliseconds, and 60.5% of subjects had left bundle-branch block (LBBB). Patients with LBBB experienced a 25.3-mL/m2 mean reduction in left ventricular end-systolic volume index (P<0.0001), whereas non-LBBB patients had smaller decreases (6.7 mL/m2; P=0.18). Baseline QRS duration was also a strong predictor of change in left ve...

Application of principal component analysis to ECG signals for automated diagnosis of cardiac health

Abstract: Electrocardiogram (ECG) is the P, QRS, T wave indicating the electrical activity of the heart. The subtle changes in amplitude and duration of ECG cannot be deciphered precisely by the naked eye, hence imposing the need for a computer assisted diagnosis tool. In this paper we have automatically classified five types of ECG beats of MIT-BIH arrhythmia database. The five types of beats are Normal (N), Right Bundle Branch Block (RBBB), Left Bundle Branch Block (LBBB), Atrial Premature Contraction (APC) and Ventricular Premature Contraction (VPC). In this work, we have compared the performances of three approaches. The first approach uses principal components of segmented ECG beats, the second approach uses principal components of error signals of linear prediction model, whereas the third approach uses principal components of Discrete Wavelet Transform (DWT) coefficients as features. These features from three approaches were independently classified using feed forward neural network (NN) and Least Square-Support Vector Machine (LS-SVM). We have obtained the highest accuracy using the first approach using principal components of segmented ECG beats with average sensitivity of 99.90%, specificity of 99.10%, PPV of 99.61% and classification accuracy of 98.11%. The system developed is clinically ready to deploy for mass screening programs.

Left ventricular longitudinal function predicts life-threatening ventricular arrhythmia and death in adults with repaired tetralogy of fallot

Abstract: Background— Sudden cardiac death and life-threatening ventricular arrhythmia remain a concern in adult patients with repaired tetralogy of Fallot. Longitudinal left ventricular (LV) function is sensitive in detecting early myocardial damage and may have prognostic implications in this setting. Methods and Results— We included 413 tetralogy of Fallot patients (age, 36±13 years; QRS duration, 148±27 milliseconds; LV ejection fraction, 55±10%). A composite end point of sudden cardiac death/life-threatening ventricular arrhythmia (sustained ventricular tachycardia, resuscitated sudden cardiac death, or appropriate implantable cardioverter-defibrillator discharge) was used. During a median follow-up of 2.9 years, 5 patients died suddenly, 9 had documented sustained ventricular tachycardia, and another 5 had appropriate implantable cardioverter-defibrillator shocks. On univariate Cox analysis, QRS duration (hazard ratio [HR], 1.02 per 1 ms; P =0.046), right atrial area (HR, 1.05 per 1 cm 2 ; P =0.02), right ventricular fractional area change (HR, 0.94 per 1%; P =0.02), right ventricular outflow tract diameter (HR, 1.08 per 1 mm; P =0.01), mitral annular plane systolic excursion (HR, 0.84 per 1 mm; P =0.03), and LV global longitudinal 2-dimensional strain (HR, 0.87 per 1%; P =0.03) were related to the combined end point. On bivariable analysis, mitral annular plane systolic excursion and LV global longitudinal 2-dimensional strain were related to outcome independently of QRS duration ( P =0.002 and P =0.01, respectively). In addition, a combination of echocardiographic variables, including right atrial area, right ventricular fractional area change, and LV global longitudinal 2-dimensional strain or mitral annular plane systolic excursion, was also found to be significantly related to outcome ( P Conclusions— LV longitudinal dysfunction was associated with greater risk of sudden cardiac death/life-threatening ventricular arrhythmias. In combination with echocardiographic right heart variables, also available from routine echocardiography, these measures provide important outcome information and should be considered a useful adjunct to established markers such as QRS duration in the estimation of prognosis in this challenging population.

Cardiac Resynchronization Therapy in Patients with Permanent Atrial Fibrillation: Results from the Resynchronization for Ambulatory Heart Failure Trial (RAFT)

Abstract: Background—Cardiac resynchronization (CRT) prolongs survival in patients with systolic heart failure and QRS prolongation. However, most trials excluded patients with permanent atrial fibrillation. Methods and Results—The Resynchronization for Ambulatory Heart Failure Trial (RAFT) randomized patients to an implantable cardioverter defibrillator (ICD) or ICD+CRT, stratified by the presence of permanent atrial fibrillation. Patients with permanent atrial fibrillation were randomized to CRT-ICD (n=114) or ICD (n=115). Patients receiving a CRT-ICD were similar to those receiving an ICD: age (71.6±7.3 versus 70.4±7.7 years), left ventricular ejection fraction (22.9±5.3% versus 22.3±5.1%), and QRS duration (151.0±23.6 versus 153.4±24.7 ms). There was no difference in the primary outcome of death or heart failure hospitalization between those assigned to CRT-ICD versus ICD (hazard ratio, 0.96; 95% CI, 0.65–1.41; P=0.82). Cardiovascular death was similar between treatment arms (hazard ratio, 0.97; 95% CI, 0.55–1....

The terminal part of the QT interval (T peak to T end): a predictor of mortality after acute myocardial infarction.

Abstract: Background: The terminal part of the QT interval (T peak to T end; Tp-e)—an index for dispersion of cardiac repolarization—is often prolonged in patients experiencing malignant ventricular arrhythmias after acute myocardial infarction (AMI). We wanted to explore whether high Tp-e might predict mortality or fatal arrhythmia post-AMI. Methods: Tp-e was measured prospectively in 1359/1384 (98.2%) consecutive patients with ST elevation (n = 525) or non-ST elevation (n = 859) myocardial infarction (STEMI or NSTEMI) admitted for coronary angiography. Results: Tp-e was significantly correlated with age, heart rate (HR), heart failure, LVEF, creatinine, three-vessel disease, previous AMI and QRS and QT duration. During a mean follow-up of 1.3 years (range 0.4–2.3),109 patients (7.9%) died; 25, 45, and 39 from cardiac arrhythmia, nonarrhythmic cardiac causes and other causes, respectively. Long Tp-e was strongly associated with increased risk of death, and Tp-e remained a significant predictor of death in multivariable Cox analyses (RR 1.5, 95% CI[1.3–1.7]). HR-corrected Tp-e (cTp-e) was the strongest predictor of death (RR 1.6 [1.4–1.9]). Tp-e and cTp-e were particularly strong predictors of fatal cardiac arrhythmia (RR 1.6 [1.2–2.1] and RR 1.8 [1.4–2.4]). Findings were similar in STEMI and NSTEMI. When comparing two methods for measuring Tp-e, one including the tail of the T wave and one not, the former had markedly higher predictive power (P < 0.001). Conclusion: Tp-e, and in particular cTp-e, were strong predictors of mortality during the first year post-AMI, and should be further evaluated as prognostic factors additional to established post-AMI risk factors.

Duration of QRS Complex in Resting Electrocardiogram Is a Predictor of Sudden Cardiac Death in Men

Abstract: Background—Previous studies indicate that increased QRS duration in ECG is related to the risk of all-cause death. However, the association of QRS duration with the risk of sudden cardiac death (SCD) is not well documented in large population-based studies. Our aim was to examine the relation of QRS duration with SCD in a population-based sample of men. Methods and Results—This prospective study was based on a cohort of 2049 men aged 42 to 60 years at baseline with a 19-year follow-up, during which a total of 156 SCDs occurred. As a continuous variable, each 10-ms increase in QRS duration was associated with a 27% higher risk for SCD (relative risk, 1.27; 95% confidence interval, 1.14–1.40; P 110 ms (highest quintile) had a 2.50-fold risk for SCD (relative risk, 2.50; 95% confidence interval, 1.38–4.55; P=0.002) compared with those with QRS duration of <96 ms (lowest quintile), after adjustment for established key demographic and clinical risk factors (age, alcohol c...

Early Repolarization Is an Independent Predictor of Occurrences of Ventricular Fibrillation in the Very Early Phase of Acute Myocardial Infarction

Abstract: Background— Recent evidence has linked early repolarization (ER) to idiopathic ventricular fibrillation (VF) in patients without structural heart disease. However, no studies have clarified whether or not there is an association between ER and the VF occurrences after the onset of an acute myocardial infarction (AMI). Methods and Results— This study retrospectively included 220 consecutive patients with an AMI (57 female; mean age, 69 ± 11 years) in whom the 12-lead ECGs before the AMI onset could be evaluated. The patients were classified on the basis of a VF occurrence within 48 hours after the AMI onset. Early repolarization was defined as an elevation of the QRS-ST junction of >0.1 mV from baseline in at least 2 inferior or lateral leads, manifested as QRS slurring or notching. Twenty-one (10%) patients had a VF occurrence within 48 hours of the AMI onset. A multivariate analysis revealed that ER (odds ratio [OR], 7.31; 95% confidence interval [CI], 2.21–24.14; P <0.01), a time from the onset to admission of <180 minutes (OR, 3.77; 95% CI, 1.13–12.59; P <0.05), and a Killip class greater than I (OR, 13.60; 95% CI, 3.43–53.99; P <0.001) were independent predictors of VF occurrences. As features of the ER pattern, a J-point elevation in the inferior leads, greater magnitude of the J-point elevation, notched morphology of the ER, and ER with a horizontal/descending ST segment, all were significantly associated with a VF occurrence. Conclusions— The presence of ER increased the risk of VF occurrences within 48 hours after the AMI onset.

QRS fragmentation: diagnostic and prognostic significance.

Abstract: Fragmentation of QRS (fQRS) complex is an easily evaluated non-invasive electrocardiographic parameter. Fragmentation of narrow QRS is defined as presence of an additional R wave (R') or notching in the nadir of the S wave, or the presence of > 1 R' in 2 contiguous leads, corresponding to a major coronary artery territory on the resting 12-lead ECG. Fragmentation of wide complex QRS consists of various RSR patterns, with more than 2 R waves (R'') or more than 2 notches in the R wave, or more than 2 notches in the downstroke or upstroke of the S wave. Presence of fQRS has been associated with alternation of myocardial activation due to myocardial scar and myocardial fibrosis. Initial studies reported higher sensitivity of fQRS than Q wave for detecting myocardial scar and postulated that the presence of fQRS could be a good predictor of cardiac events among the patients with coronary artery disease. The presence of fQRS has been investigated among the patients with ischemic and non-ischemic cardiomyopathy suggesting that this ECG parameter may affect prognosis and risk of sudden cardiac death, risk of implantable cardioverter-defibrillator therapy and response to cardiac resynchronization therapy. In addition, there is evidence that fQRS could play an important role as screening and prognostic tool among the patients with Brugada syndrome, long QT syndrome, arrhythmogenic right ventricular dysplasia and cardiac sarcoidosis. This paper reviews definition, diagnostic and prognostic value of fQRS in different patient populations.

The Benefit of Cardiac Resynchronization Therapy and QRS Duration: A Meta-Analysis

Abstract: CRT and QRS Duration. Background: Cardiac resynchronization therapy (CRT) improves outcomes in patients with heart failure (HF) because of reduced left ventricular systolic function and a wide QRS complex. Whether this benefit is consistent across all degrees of QRS widening is unclear. We performed a meta-analysis of randomized clinical trials to evaluate the impact of QRS duration on the efficacy of CRT. Methods and Results: We searched MEDLINE and EMBASE databases for studies evaluating the efficacy of CRT in patients with HF. Only trials that reported subgroup data according to QRS duration were included. Hazard ratios (HR) with 95% confidence interval (CI) were calculated using a random effects model. Five trials involving 6,501 patients (4,437 with QRS ≥ 150 ms and 2,064 with QRS < 150 ms) were included. Three trials, enrolling patients with mild to moderate HF, compared CRT-implantable cardioverter defibrillator with CRT, whereas CRT versus medical therapy was compared in the other 2 trials, which included patients with advanced HF. Based on the pooled estimate across the 5 studies, CRT significantly decreased the primary endpoint of death or hospitalization for HF in patients with QRS ≥ 150 ms (HR = 0.58, 95% CI: 0.50–0.68; P < 0.00001), but not in patients with QRS < 150 ms (HR = 0.95, 95% CI: 0.83–1.10; P = 0.51). These results were consistent across all degrees of HF severity. Conclusions: The benefit of CRT seems to be dependent on QRS duration. Available data suggest a significant benefit associated with CRT in patients with QRS ≥ 150 ms, but not in patients with QRS < 150 ms. Further studies are needed to identify patients with QRS < 150 ms who might benefit from CRT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 163-168, February 2012)

Pacing-induced cardiomyopathy in patients with right ventricular stimulation for >15 years

Abstract: Aims The prevalence of pacing-induced cardiomyopathy (PiCMP) has been reported to be 9% 1 year after implantation. As long-term data are sparse, the aim of our study was to evaluate the prevalence of PiCMP in a cohort of patients with at least 15 years of right ventricular (RV) pacing. Methods and results Inclusion criteria were RV stimulation for at least 15 years due to atrioventricular block III° and absence of structural heart disease at the time of initial implantation. All patients were examined by echocardiography and spiroergometry. Pacing-induced cardiomyopathy was pre-defined as left ventricular (LV) ejection fraction (LVEF) ≤45%, dyskinesia during RV pacing and absence of other known causes of cardiomyopathy. Twenty-six patients from our outpatient department met the inclusion criteria. Pacing-induced cardiomyopathy was diagnosed in four patients (15.4%). Echocardiography showed significant LV remodelling in PiCMP patients [LVEF 41.0 ± 4.5%, LV end-diastolic diameter (LVEDD) 54.0 ± 2.7 mm] compared with patients with preserved LVEF (LVEF 61.2 ± 5.8%, P = 0.002, LVEDD 45.6 ± 4.0 mm, P = 0.004). There were no significant differences regarding age, gender, duration of RV pacing, heart rate, interventricular mechanical delay, QRS duration or prevalence of sinus rhythm, and arterial hypertension between both groups. The longest intraventricular delay was significantly shorter in patients with preserved LVEF (65.5 ± 43.0 ms) compared with PiCMP patients (112.5 ± 15.0 ms, P = 0.043). Exercise capacity and quality of life did not differ significantly between both groups. Conclusion Considering the very long duration of RV stimulation in our study population (24.6 ± 6.6 years), the prevalence of PiCMP was remarkably low. Pacing-induced cardiomyopathy was associated with more pronounced intraventricular dyssynchrony.

Association of early repolarization and sudden cardiac death during an acute coronary event.

Abstract: Background— Electrocardiographic early repolarization (ER) pattern has been previously associated with arrhythmic mortality and with an increased risk of ventricular fibrillation. We hypothesized that there is an association between ER and sudden cardiac death (SCD) during an acute coronary event. Methods and Results— The present study included 432 consecutive victims of SCD because of acute coronary event and 532 survivors of such an event, in whom 12-lead ECGs recorded before and unrelated to the event could be evaluated. SCDs were verified by medicolegal autopsy to be because of acute coronary event. ER was defined as an elevation of the QRS-ST junction in at least 2 inferior or lateral leads, manifested as QRS notching or slurring. The prevalence of ER pattern ≥0.1 mV was more common in cases (62/432; 14.4%) than controls (42/532; 7.9%) ( P =0.001). The victims of SCD were younger, were more commonly men and smokers, had lower body mass index, had elevated heart rate, had prolonged QRS complex, and had lower prevalence of history of prior cardiovascular disease than controls. After adjustments for baseline differences, the odds ratio for J waves without ST-segment elevation in the SCD group was 2.15 (95% CI, 1.20–3.85; P =0.01). Conclusions— Higher prevalence of ER in a standard 12-lead ECG in victims of SCD than in survivors of an acute coronary event suggests that the presence of ER increases the vulnerability to fatal arrhythmia during acute myocardial ischemia and provides a plausible mechanistic link between this ECG pattern and higher arrhythmic mortality of middle-aged/elderly subjects.

The relationship of QRS morphology and mechanical dyssynchrony to long-term outcome following cardiac resynchronization therapy

Abstract: Aims Because benefits of cardiac resynchronization therapy (CRT) appear to be less favourable in non-left bundle branch block (LBBB) patients, this prospective longitudinal study tested the hypothesis that QRS morphology and echocardiographic mechanical dyssynchrony were associated with long-term outcome after CRT Methods and results Two-hundred and seventy-eight consecutive New York Heart Association class III and IV CRT patients with QRS ≥120 ms and ejection fraction ≤35% were studied The pre-specified primary endpoint was death, heart transplant, or left ventricular assist device over 4 years Dyssynchrony assessed before CRT included interventricular mechanical delay (IVMD) and speckle-tracking radial strain using pre-specified cut-offs for each Of 254 with baseline quantitative echocardiographic data available, 128 had LBBB, 81 had intraventricular conduction delay (IVCD), and 45 had right bundle branch block (RBBB) Radial dyssynchrony was observed in 85% of the patients with LBBB, 59% with IVCD*, and 40% with RBBB* (* P < 001 vs LBBB) Of 248 (98%) with follow-up, LBBB patients had a significantly more favourable long-term survival than non-LBBB patients However, non-LBBB patients with dyssynchrony had a more favourable event-free survival than those without dyssynchrony: radial dyssynchrony hazard ratio 26, 95% confidence interval (CI) 147–453 ( P = 00008) and IVMD hazard ratio 49, 95% CI 260–916 ( P = 00007) Right bundle branch block patients who lacked dyssynchrony had the least favourable outcome Conclusion Non-LBBB patients with dyssynchrony had a more favourable long-term survival than non-LBBB patients who lacked dyssynchrony Mechanical dyssynchrony and QRS morphology are associated with outcome following CRT

Fragmented QRS: What is the meaning?

Abstract: Fragmented QRS (fQRS) is a convenient marker of myocardial scar evaluated by 12-lead electrocardiogram (ECG) recording. fQRS is defined as additional spikes within the QRS complex. In patients with CAD, fQRS was associated with myocardial scar detected by single photon emission tomography and was a predictor of cardiac events. fQRS was also a predictor of mortality and arrhythmic events in patients with reduced left ventricular function. The usefulness of fQRS for detecting myocardial scar and for identifying high-risk patients has been expanded to various cardiac diseases, such as cardiac sarcoidosis, arrhythmogenic right ventricular cardiomyopathy, acute coronary syndrome, Brugada syndrome, and acquired long QT syndrome. fQRS can be applied to patients with wide QRS complexes and is associated with myocardial scar and prognosis. Myocardial scar detected by fQRS is associated with subsequent ventricular dysfunction and heart failure and is a substrate for reentrant ventricular tachyarrhythmias.

QRS fragmentation and the risk of sudden cardiac death in MADIT II.

Abstract: QRS Fragmentation and the Risk of Sudden Cardiac Death in MADIT II. Background: QRS fragmentation (fQRS) has been reported as a useful ECG parameter in predicting mortality in high-risk postinfarction patients. Its prognostic value for sudden cardiac death (SCD) and ventricular arrhythmias in ischemic cardiomyopathy (ICM) remains unknown. Methods: MADIT II enrollment 12-lead ECGs were analyzed for fQRS defined as RSR’ patterns (≥1 R’ or notching of S or R wave) in patients with a normal QRS duration and >2 notches on the R or S wave in patients with abnormal QRS duration, present in 2 contiguous leads. Exclusion criteria included a paced rhythm and an uninterpretable or incomplete ECG. Study endpoints included SCD, SCD or appropriate implantable cardioverter defibrillator (ICD) shock, and total mortality (TM). Results: Of the 1,232 ECGs reviewed, 1,040 were of suitable quality for fQRS analysis. QRS fragmentation was found in 33% of patients in any leads, in 10% of patients in anterior leads, in 8% of patients in lateral leads and in 21% of patients in inferior leads. Anterior and lateral location of QRS fragmentation was not associated with follow-up events. Inferior location of fQRS was found to be predictive of SCD/ICD shock (hazard ratio [HR] 1.46, P = 0.032), SCD (HR 2.05, P = 0.007), and TM (HR 1.44, P = 0.036). This association was driven primarily by the increase in events found in LBBB patients: SCD/ICD shock (HR 2.05, P = 0.046), SCD (HR 4.24, P = 0.002), and TM (HR 2.82, P = 0.001). Conclusions: Fragmented QRS, especially identified in inferior leads, is predictive of SCD, SCD or appropriate ICD shock, and all-cause mortality in patients with ICM. Identifying inferior fQRS in patients with LBBB is of particular prognostic significance and should reinforce the use of ICD therapy in this high-risk group. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1343-1348, December 2012)

Analyzing ECG for cardiac arrhythmia using cluster analysis

Abstract: This work proposes a method of analyzing ECG signal to diagnose cardiac arrhythmias utilizing the cluster analysis (CA) method The proposed method can accurately classify and distinguish the difference between normal heartbeats (NORM) and abnormal heartbeats Abnormal heartbeats may include the following: left bundle branch block (LBBB), right bundle branch block (RBBB), ventricular premature contractions (VPC), and atrial premature contractions (APC) Analysis of ECG signal consists of three major stages: (i) detecting the QRS waveform; (ii) selecting qualitative features; and (iii) determining heartbeat case The ECG signals in the MIT-BIH arrhythmia database are adopted as reference data for accomplishing the first two stages, and cluster analysis is used to determine patient heartbeat case In the experiments, the sensitivity is 9559%, 9132%, 9050%, 9451%, and 9377% for heartbeat case NORM, LBBB, RBBB, VPC, and APC, respectively The total classification accuracy (TCA) was about 9430%

Relations between QRS|T Angle, Cardiac Risk Factors, and Mortality in the Third National Health and Nutrition Examination Survey (NHANES III)

Abstract: On the surface electrocardiogram, an abnormally wide QRS|T angle reflects changes in the regional action potential duration profiles and in the direction of the repolarization sequence, which is thought to increase the risk of ventricular arrhythmia. We investigated the relation between an abnormal QRS|T angle and mortality in a nationally representative sample of subjects without clinically evident heart disease. We studied 7,052 participants ≥40 years old in the third National Health and Nutrition Examination Survey with 12-lead electrocardiograms. Those with self-reported or electrocardiographic evidence of a previous myocardial infarction, QRS duration of ≥120 ms, or history of heart failure were excluded. Borderline and abnormal spatial QRS|T angles were defined according to gender-specific 75th and 95th percentiles of frequency distributions. All-cause (1,093 women and 1,191 men) and cardiovascular (462 women and 455 men) mortality during the 14-year period was assessed through linkage with the National Death Index. On multivariate analyses, an abnormal spatial QRS|T angle was associated with an increased hazard ratio (HR) for cardiovascular mortality in women (HR 1.82, 95% confidence interval 1.05 to 3.14) and men (HR 2.21, 95% confidence interval 1.32 to 3.68). Also, the multivariate adjusted HR for all-cause mortality associated with an abnormal QRS|T angle was 1.30 (95% confidence interval 0.95 to 1.78) for women and 1.87 (95% confidence interval 1.29 to 2.7) for men. A borderline QRS|T angle was not associated with an increased risk of all-cause or cardiovascular mortality. In conclusion, an abnormal QRS|T angle, as measured on a 12-lead electrocardiogram, was associated with an increased risk of cardiovascular and all-cause mortality in this population-based sample without known heart disease.

Using the surface electrocardiogram to localize the origin of idiopathic ventricular tachycardia

Abstract: The surface electrocardiogram (ECG) is a useful tool to help identify the sites of origin of ventricular tachycardia (VT). Despite such limitations as chest wall deformity and metabolic and drug effects, the analysis of the QRS morphologic patterns and vectors can discern the site of activation of myocardium. There have been described numerous reports about ECG features of idiopathic left- and right-ventricular VT. In this review, we summarized typical ECG characteristics according to the VT sites of origin based on previous reports, with anatomical considerations of the left and right ventricles, including the outflow tracts and epicardium.