Showing papers on "QRS complex published in 2017"

Benefits of Permanent His Bundle Pacing Combined With Atrioventricular Node Ablation in Atrial Fibrillation Patients With Heart Failure With Both Preserved and Reduced Left Ventricular Ejection Fraction.

Abstract: Background Clinical benefits from His bundle pacing (HBP) in heart failure patients with preserved and reduced left ventricular ejection fraction are still inconclusive. This study evaluated clinical outcomes of permanent HBP in atrial fibrillation patients with narrow QRS who underwent atrioventricular node ablation for heart failure symptoms despite rate control by medication. Methods and Results The study enrolled 52 consecutive heart failure patients who underwent attempted atrioventricular node ablation and HBP for symptomatic atrial fibrillation. Echocardiographic left ventricular ejection fraction and left ventricular end‐diastolic dimension, New York Heart Association classification and use of diuretics for heart failure were assessed during follow‐up visits after permanent HBP. Of 52 patients, 42 patients (80.8%) received permanent HBP and atrioventricular node ablation with a median 20‐month follow‐up. There was no significant change between native and paced QRS duration (107.1±25.8 versus 105.3±23.9 milliseconds, P =0.07). Left ventricular end‐diastolic dimension decreased from the baseline ( P <0.001), and left ventricular ejection fraction increased from baseline ( P <0.001) in patients with a greater improvement in heart failure with reduced ejection fraction patients (N=20) than in heart failure with preserved ejection fraction patients (N=22). New York Heart Association classification improved from a baseline 2.9±0.6 to 1.4±0.4 after HBP in heart failure with reduced ejection fraction patients and from a baseline 2.7±0.6 to 1.4±0.5 after HBP in heart failure with preserved ejection fraction patients. After 1 year of HBP, the numbers of patients who used diuretics for heart failure decreased significantly ( P <0.001) when compared to the baseline diuretics use. Conclusions Permanent HBP post–atrioventricular node ablation significantly improved echocardiographic measurements and New York Heart Association classification and reduced diuretics use for heart failure management in atrial fibrillation patients with narrow QRS who suffered from heart failure with preserved or reduced ejection fraction.

Traditional and novel electrocardiographic conduction and repolarization markers of sudden cardiac death

Abstract: Sudden cardiac death, frequently due to ventricular arrhythmias, is a significant problem globally. Most affected individuals do not arrive at hospital in time for medical treatment. Therefore, there is an urgent need to identify the most-at-risk patients for insertion of prophylactic implantable cardioverter defibrillators. Clinical risk markers derived from electrocardiography are important for this purpose. They can be based on repolarization, including corrected QT (QTc) interval, QT dispersion (QTD), interval from the peak to the end of the T-wave (Tpeak – Tend), (Tpeak – Tend)/QT, T-wave alternans (TWA), and microvolt TWA. Abnormal repolarization properties can increase the risk of triggered activity and re-entrant arrhythmias. Other risk markers are based solely on conduction, such as QRS duration (QRSd), which is a surrogate marker of conduction velocity (CV) and QRS dispersion (QRSD) reflecting CV dispersion. Conduction abnormalities in the form of reduced CV, unidirectional block, together with a functional or a structural obstacle, are conditions required for circus-type or spiral wave re-entry. Conduction and repolarization can be represented by a single parameter, excitation wavelength ( λ = CV × effective refractory period). λ is an important determinant of arrhythmogenesis in different settings. Novel conduction–repolarization markers incorporating λ include Lu e t al. ' index of cardiac electrophysiological balance (iCEB: QT/QRSd), [QRSD× (Tpeak − Tend)/QRSd] and [QRSD × (Tpeak − Tend)/(QRSd × QT)] recently proposed by Tse and Yan. The aim of this review is to provide up to date information on traditional and novel markers and discuss their utility and downfalls for risk stratification.

A QRS Detection and R Point Recognition Method for Wearable Single-Lead ECG Devices

Abstract: In the new-generation wearable Electrocardiogram (ECG) system, signal processing with low power consumption is required to transmit data when detecting dangerous rhythms and to record signals when detecting abnormal rhythms. The QRS complex is a combination of three of the graphic deflection seen on a typical ECG. This study proposes a real-time QRS detection and R point recognition method with low computational complexity while maintaining a high accuracy. The enhancement of QRS segments and restraining of P and T waves are carried out by the proposed ECG signal transformation, which also leads to the elimination of baseline wandering. In this study, the QRS fiducial point is determined based on the detected crests and troughs of the transformed signal. Subsequently, the R point can be recognized based on four QRS waveform templates and preliminary heart rhythm classification can be also achieved at the same time. The performance of the proposed approach is demonstrated using the benchmark of the MIT-BIH Arrhythmia Database, where the QRS detected sensitivity (Se) and positive prediction (+P) are 99.82% and 99.81%, respectively. The result reveals the approach’s advantage of low computational complexity, as well as the feasibility of the real-time application on a mobile phone and an embedded system.

QRS fragmentation is superior to QRS duration in predicting mortality in adults with tetralogy of Fallot

Abstract: Background Although QRS duration >180 ms has prognostic value in adults with tetralogy of Fallot (TOF), its sensitivity to predict mortality is low. Fragmented QRS complexes, a simple measurement on ECG, are related to myocardial fibrosis and dysfunction in patients with TOF. Our objective was to determine whether QRS fragmentation predicts major outcomes in TOF. Methods This multicentre study included adult patients with TOF from a prospective registry. Notches in the QRS complex in ≥2 contiguous leads on a 12-lead ECG, not related to bundle branch block, were defined as QRS fragmentation, which was classified as none, moderate (≤4 leads) or severe (≥5 leads). The primary and secondary outcomes were all-cause mortality and clinical ventricular arrhythmia, respectively. Results A total of 794 adult patients with TOF (median age 27 years, 55% male; 52% no QRS fragmentation, 32% moderate, 16% severe) were included. During long-term (median 10.4 years) follow-up, 46 (6%) patients died and 35 (4%) patients had ventricular arrhythmias. Overall, 10-year survival was 98% in patients without fragmented QRS complexes, 93% in patients with moderate QRS fragmentation and 81% in patients with severe QRS fragmentation. In multivariable Cox hazards regression analysis, extent of QRS fragmentation (HR: 2.24/class, 95% CI 1.48 to 3.40, p<0.001) remained independently predictive for mortality, whereas QRS duration was not predictive (p=0.85). The extent of QRS fragmentation was also independently predictive for ventricular arrhythmia (HR: 2.00/class, 95% CI 1.26 to 3.16, p=0.003). Conclusions The extent of QRS fragmentation is superior to QRS duration in predicting mortality in adult patients with TOF and may be used in risk stratification.

Pulmonary Right Ventricular Resynchronization in Congenital Heart Disease: Acute Improvement in Right Ventricular Mechanics and Contraction Efficiency.

Abstract: Background— Electromechanical discoordination may contribute to long-term pulmonary right ventricular (RV) dysfunction in patients after surgery for congenital heart disease. We sought to evaluate changes in RV function after temporary RV cardiac resynchronization therapy. Methods and Results— Twenty-five patients aged median 12.0 years after repair of tetralogy of Fallot and similar lesions were studied echocardiographically (n=23) and by cardiac catheterization (n=5) after primary repair (n=4) or after surgical RV revalvulation for significant pulmonary regurgitation (n=21). Temporary RV cardiac resynchronization therapy was applied in the presence of complete right bundle branch block by atrial-synchronized RV free wall pacing in complete fusion with spontaneous ventricular depolarization using temporary electrodes. The q-RV interval at the RV free wall pacing site (mean 77.2% of baseline QRS duration) confirmed pacing from a late activated RV area. RV cardiac resynchronization therapy carried significant decrease in QRS duration ( P P =0.002), pulmonary artery velocity time integral ( P =0.006), and RV maximum +dP/dt ( P P =0.006). RV mechanical synchrony improved: septal-to-lateral RV mechanical delay decreased ( P P =0.001). Conclusions— In patients with congenital heart disease and right bundle branch block, RV cardiac resynchronization therapy carried multiple positive effects on RV mechanics, synchrony, and contraction efficiency.

A convolutional neural network based approach to QRS detection

Abstract: In this paper we present a QRS detection algorithm based on pattern recognition as well as a new approach to ECG baseline wander removal and signal normalization. Each point of the zero-centred and normalized ECG signal is a QRS candidate, while a 1-D CNN classifier serves as a decision rule. Positive outputs from the CNN are clustered to form final QRS detections. The data is obtained from the 44 non-pacemaker recordings of the MIT-BIH arrhythmia database. Classifier was trained on 22 recordings and the remaining ones are used for performance evaluation. Our method achieves a sensitivity of 99.81% and 99.93% positive predictive value, which is comparable with most state-of-the-art solutions. This approach opens new possibilities for improvements in heartbeat classification as well as P and T wave detection problems.

Severe Hyperkalemia: Can the Electrocardiogram Risk Stratify for Short-term Adverse Events?

Abstract: Introduction: The electrocardiogram (ECG) is often used to identify which hyperkalemic patients are at risk for adverse events. However, there is a paucity of evidence to support this practice. This study analyzes the association between specific hyperkalemic ECG abnormalities and the development of short-term adverse events in patients with severe hyperkalemia. Methods: Records of all adult patients with K+ ≥6.5 mEq/L in the hospital laboratory database from August 15, 2010 through January 30, 2015 were collected. A chart review identified patient demographics, concurrent laboratory values, ECG within one hour of potassium measurement, treatments and occurrence of adverse events within 6 hours of ECG. Adverse events were defined as symptomatic bradycardia, ventricular tachycardia, ventricular fibrillation, cardiopulmonary resuscitation and/or death. Two emergency physicians blinded to study objective independently examined each ECG for rate, rhythm, peaked T wave, PR interval duration and QRS wave duration. Odds ratios were calculated to determine the association between specific hyperkalemic ECG abnormalities and short-term adverse events. Results: A total of 188 patients with severe hyperkalemia were included in the final study group. Adverse events occurred within 6 hours in 28 patients (15%): symptomatic bradycardia (n=22), death (n=4), ventricular tachycardia (n=2) and cardiopulmonary resuscitation (n=2). All patients who had a short-term adverse event had a preceding ECG that demonstrated at least one hyperkalemic abnormality (100%, 95% CI: 85.7-100%). An increased likelihood of short-term adverse event was found for hyperkalemic patients whose ECG demonstrated QRS prolongation (OR 6.11, 95%CI 2.35-15.92), bradycardia (HR<50) (OR 60.27, 95%CI 17.28-210.18), and/or junctional rhythm (OR 25.24, 95%CI 7.24-88). There was no statistically significant correlation between peaked T waves and short-term adverse events (OR 0.73, 95%CI: 0.29-1.84). Conclusion: Our findings support the use of the ECG to risk stratify patients with severe hyperkalemia.

Inferior lead discordance in ventricular arrhythmias: A specific marker for certain arrhythmia locations.

Abstract: Background Most idiopathic ventricular arrhythmias (VAs) originate from the outflow tracts and are characterized by an inferior axis on the 12-lead ECG. A group of patients will exhibit inferior lead discordance (ILD), demonstrating a positive QRS in lead II with negative QRS in III or the opposite finding. Methods and results We identified patients undergoing ablation of idiopathic premature ventricular contractions (PVCs) or ventricular tachycardia (VT) between 2013 and 2015. The site of earliest activation was determined using electroanatomic mapping and intracardiac echocardiography. Out of 281 patients, 25 (8.9%) exhibited ILD. In patients with positive/negative discordance (n = 18) the source was mapped to the parahisian region in 14 cases and to the right ventricular (RV) moderator band (MB) or papillary muscles (PMs) in 4, while all those with negative/positive discordance (n = 7) were mapped to the anterolateral PM (ALPM). In the group with positive/negative discordance, a later precordial transition (>V4), wider QRS duration and the presence of notch in the inferior leads pointed towards a RV MB/PM origin. Complete PVC/VT suppression was achieved in 72%. In 2 patients with parahisian PVCs, ablation was not attempted due to risk of heart block. Conclusions The presence of ILD is associated with particular anatomical locations, namely the parahisian region, RV MB/PM and ALPM. The outcomes of ablation are more modest compared to other idiopathic VAs, reflecting the technical difficulties associated with these anatomical locations, such as the proximity to the conduction system in parahisian VAs or stability issues when ablating the PMs or MB. This article is protected by copyright. All rights reserved

Discrete Wavelet Transform Based Algorithm for Recognition of QRS Complexes

Abstract: This paper proposes the application of Discrete Wavelet Transform (DWT) to detect the QRS (ECG is characterized by a recurrent wave sequence of P, QRS and T-wave) of an electrocardiogram (ECG) signal. Wavelet Transform provides localization in both time and frequency. In preprocessing stage, DWT is used to remove the baseline wander in the ECG signal. The performance of the algorithm of QRS detection is evaluated against the standard MIT BIH (Massachusetts Institute of Technology, Beth Israel Hospital) Arrhythmia database. The average QRS complexes detection rate of 98.1 % is achieved.

Diffuse Myocardial Fibrosis Reduces Electrocardiographic Voltage Measures of Left Ventricular Hypertrophy Independent of Left Ventricular Mass

Abstract: Background Myocardial fibrosis quantified by myocardial extracellular volume fraction (ECV) and left ventricular mass (LVM) index (LVMI) measured by cardiovascular magnetic resonance might represent independent and opposing contributors to ECG voltage measures of left ventricular hypertrophy (LVH). Diffuse myocardial fibrosis can occur in LVH and interfere with ECG voltage measures. This phenomenon could explain the decreased sensitivity of LVH detectable by ECG, a fundamental diagnostic tool in cardiology. Methods and Results We identified 77 patients (median age, 53 [interquartile range, 26–60] years; 49% female) referred for contrast‐enhanced cardiovascular magnetic resonance with ECV measures and 12‐lead ECG. Exclusion criteria included clinical confounders that might influence ECG measures of LVH. We evaluated ECG voltage‐based LVH measures, including Sokolow‐Lyon index, Cornell voltage, 12‐lead voltage, and the vectorcardiogram spatial QRS voltage, with respect to LVMI and ECV. ECV and LVMI were not correlated ( R 2=0.02; P =0.25). For all voltage‐related parameters, higher LVMI resulted in greater voltage ( r =0.33–0.49; P <0.05 for all), whereas increased ECV resulted in lower voltage ( r =−0.32 to −0.57; P <0.05 for all). When accounting for body fat, LV end‐diastolic volume, and mass‐to‐volume ratio, both LVMI (β=0.58, P =0.03) and ECV (β=−0.46, P <0.001) were independent predictors of QRS voltage (multivariate adjusted R 2=0.39; P <0.001). Conclusions Myocardial mass and diffuse myocardial fibrosis have independent and opposing effects upon ECG voltage measures of LVH. Diffuse myocardial fibrosis quantified by ECV can obscure the ECG manifestations of increased LVM. This provides mechanistic insight, which can explain the limited sensitivity of the ECG for detecting increased LVM.

Automatic Detection of the R Peaks in Single-Lead ECG Signal

Abstract: The accurate delineation of R peaks in an ElectroCardioGram (ECG) is required for analysis and diagnosis of various cardiac abnormalities. Detection of the R peak is a challenging task due to the presence of various artifacts and varying morphology of the ECG signal in inter- and intrasubject. In this paper, an effective and novel algorithm for the accurate detection of R peaks in the single-lead ECG signal is proposed. The QRS complex is enhanced by removing P, T waves and other artifacts using combination of wavelet transform, derivatives and Hilbert transform. The enhanced QRS complex is detected by adaptive thresholding. This method is robust against inter- and intrasubject variations of the ECG signal morphology and also provides high degree of accuracy for very noisy signals. The algorithm is tested on all the signals of MIT-BIH arrhythmia Database, QT database and noise stress database taken from physionet.org (Massachusetts Institute of Technology, Biomedical Engineering Center, Cambridge, MA, 1992. www.physionet.org/physiobank/databse/html/mitdbdir/mitdbdir.htm). The performance of the algorithm is confirmed by sensitivity of 99.9%, positive predictivity of 99.9% and detection accuracy of 99.8% for R peaks detection.

Flecainide Toxicity: A Case Report and Systematic Review of its Electrocardiographic Patterns and Management

Abstract: In the setting of flecainide toxicity, supraventricular tachycardia can manifest as a bizarre right or left bundle branch block, sometimes with a northwest axis, and can easily be mistaken for ventricular tachycardia leading to inappropriate therapy. We conducted a comprehensive literature review for cases of flecainide toxicity. We found 21 articles of flecainide toxicity in adult patients in which 22 ECG tracings were published. In patients with flecainide toxicity and QRS duration ≤ 200 ms, the ECGs were more likely to show RBBB, visible P waves (p = 0.03), and shorter QT (p = 0.02) and QTc intervals (p = 0.004). With QRS duration > 200 ms, the ECGs were more likely to show LBBB, loss of P waves, a northwest axis (p = 0.01), and longer QT and QTc intervals. Deaths were reported only in patients with QRS duration >200 ms, and the outcome of death or requirement for mechanical circulatory support was more prevalent in patients with a QRS duration > 200 ms [2/13 (15.4 %) vs. 6/10 (60 %), p = 0.04]. In patients with access to the medication, flecainide toxicity should be suspected with: (1) broad QRS, (2) RBBB morphology with QRS ≤ 200 ms; RBBB or LBBB morphology with QRS ≥ 200 ms (3) HR out of proportion to the degree of hemodynamic instability. The duration of the QRS interval is prognostic, with mortality and the requirement for mechanical circulatory support being more common in patients with a QRS > 200 ms.

Distribution and Prognostic Significance of Fragmented QRS in Patients With Brugada Syndrome.

Abstract: Background—Fragmented QRS complexes (fQRS) in the right precordial leads are associated with occurrence of ventricular fibrillation (VF) in Brugada syndrome. Recently, epicardial mapping has reveal...

Outcomes of Catheter Ablation of Idiopathic Outflow Tract Ventricular Arrhythmias With an R Wave Pattern Break in Lead V2: A Distinct Clinical Entity.

Abstract: Outflow Tract VT With Pattern Break in Lead V2Introduction In outflow tract ventricular arrhythmias (OT-VAs), an abrupt loss of the R wave in lead V2 compared to V1 and V3 (pattern break in V2–PBV2) suggests an origin close to the anterior interventricular sulcus (anatomically opposite to lead V2) and adjacent to proximal coronaries. We studied the outcome of catheter ablation of OT-VAs with a PBV2. Methods and Results Of 130 consecutive patients with idiopathic left bundle block morphology OT-VAs and transition ≤V4, 12 (9%) had PBV2. Outcomes in this group were compared to the remaining 118 patients. Patients with PBV2 were more likely to be younger (41 ± 18 vs. 50 ± 14 years, P = 0.0384) and women (11 [92%] vs. 70 [59%], P = 0.0302). The earliest activation was at the RVOT in seven, left coronary cusp (LCC) in one, anterior interventricular vein (AIV) in two and the epicardium in two. In five (42%) cases (earliest activation in the AIV in two, epicardium in two, and RVOT below the valve level in one), ablation was aborted due to proximity to the left anterior descending (LAD) coronary artery. After 36 ± 17 months and 1.3 ± 0.5 procedures, VAs elimination was achieved in 58% of patients with PBV2 compared to 89% of the reference population (P = 0.0125) with effective site in five of seven at the most anterior and leftward RVOT adjacent to the pulmonic valve (PV). Conclusions OT-VAs with PBV2 demonstrate a unique ECG pattern and challenging catheter ablation. Proximity to LAD precludes ablation in about half. Long-term VA suppression could be achieved in only 58% of cases most commonly when the earliest site is at the anterior and leftward RVOT just under the PV.

Distinctive Left Ventricular Activations Associated With ECG Pattern in Heart Failure Patients

Abstract: Background— In contrast to patients with left bundle branch block (LBBB), heart failure patients with narrow QRS and nonspecific intraventricular conduction delay (NICD) display a relatively limited response to cardiac resynchronization therapy. We sought to compare left ventricular (LV) activation patterns in heart failure patients with narrow QRS and NICD to patients with LBBB using high-density electroanatomic activation maps. Methods and Results— Fifty-two heart failure patients (narrow QRS [n=18], LBBB [n=11], NICD [n=23]) underwent 3-dimensional electroanatomic mapping with a high density of mapping points (387±349 LV). Adjunctive scar imaging was available in 37 (71%) patients and was analyzed in relation to activation maps. LBBB patients typically demonstrated (1) a single LV breakthrough at the septum (38±15 ms post-QRS onset); (2) prolonged right-to-left transseptal activation with absence of direct LV Purkinje activity; (3) homogeneous propagation within the LV cavity; and (4) latest activation at the basal lateral LV. In comparison, both NICD and narrow QRS patients demonstrated (1) multiple LV breakthroughs along the posterior or anterior fascicles: narrow QRS versus LBBB, 5±2 versus 1±1; P =0.0004; NICD versus LBBB, 4±2 versus 1±1; P =0.001); (2) evidence of early/pre-QRS LV electrograms with Purkinje potentials; (3) rapid propagation in narrow QRS patients and more heterogeneous propagation in NICD patients; and (4) presence of limited areas of late activation associated with LV scar with high interindividual heterogeneity. Conclusions— In contrast to LBBB patients, narrow QRS and NICD patients are characterized by distinct mechanisms of LV activation, which may predict poor response to cardiac resynchronization therapy.

Cardiac Resynchronization Therapy Reduces Ventricular Arrhythmias in Primary but Not Secondary Prophylactic Implantable Cardioverter Defibrillator Patients: Insight From the Resynchronization in Ambulatory Heart Failure Trial.

Abstract: Background— The RAFT (Resynchronization in Ambulatory Heart Failure Trial) demonstrated that cardiac resynchronization therapy (CRT) reduced both mortality and heart failure hospitalizations in patients with functional class II or III heart failure and widened QRS. We examined the influence of CRT on ventricular arrhythmias in patients with primary versus secondary prophylaxis defibrillator indications. Methods and Results— All ventricular arrhythmias among RAFT study participants were downloaded and adjudicated by 2 blinded reviewers with an overreader for disagreements and committee review for remaining discrepancies. Incidence of ventricular arrhythmias among patients randomized to CRT-D versus implantable cardioverter defibrillator (ICD) were compared within the groups of patients treated for primary prophylaxis and for secondary prophylaxis. Of 1798 enrolled patients, 1764 had data available for adjudication and were included. Of these, 1531 patients were implanted for primary prophylaxis, while 233 patients were implanted for secondary prophylaxis; 884 patients were randomized to ICD and 880 to CRT-D. During 5953.6 patient-years of follow-up, there were 11 278 appropriate ICD detections of ventricular arrhythmias. In the primary prophylaxis group, CRT-D significantly reduced incidence ventricular arrhythmias in comparison to ICD (hazard ratio, 0.86; 95% confidence interval, 0.74–0.99; P =0.044). This effect was not seen in the secondary prophylaxis group (hazard ratio, 1.14; 95% confidence interval, 0.82–1.58; P =0.45). CRT-D was not associated with significant differences in overall ventricular arrhythmia burden in either group. Conclusions— CRT reduced the rate of onset of new ventricular arrhythmias detected by ICDs in patients without a history of prior ventricular arrhythmias. This effect was not observed among patients who had prior ventricular arrhythmias. Clinical Trial Registration— URL: . Unique identifier: [NCT00251251][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00251251&atom=%2Fcircae%2F10%2F3%2Fe004875.atom

Restrictive Cardiomyopathies: The Importance of Noninvasive Cardiac Imaging Modalities in Diagnosis and Treatment-A Systematic Review.

Abstract: Restrictive cardiomyopathy (RCM) is the least common among cardiomyopathies. It can be idiopathic, familial, or secondary to systematic disorders. Marked increase in left and/or right ventricular filling pressures causes symptoms and signs of congestive heart failure. Electrocardiographic findings are nonspecific and include atrioventricular conduction and QRS complex abnormalities and supraventricular and ventricular arrhythmias. Echocardiography and cardiac magnetic resonance (CMR) play a major role in diagnosis. Echocardiography reveals normal or hypertrophied ventricles, preserved systolic function, marked biatrial enlargement, and impaired diastolic function, often with restrictive filling pattern. CMR offering a higher spatial resolution than echocardiography can provide detailed information about anatomic structures, perfusion, ventricular function, and tissue characterization. CMR with late gadolinium enhancement (LGE) and novel approaches (myocardial mapping) can direct the diagnosis to specific subtypes of RCM, depending on the pattern of scar formation. When noninvasive studies have failed, endomyocardial biopsy is required. Differentiation between RCM and constrictive pericarditis (CP), nowadays by echocardiography, is important since both present as heart failure with normal-sized ventricles and preserved ejection fraction but CP can be treated by means of anti-inflammatory and surgical treatment, while the treatment options of RCM are dictated by the underlying condition. Prognosis is generally poor despite optimal medical treatment.

Population-based values and abnormalities of the electrocardiogram in the general Dutch population: The LifeLines Cohort Study.

Abstract: Background Our aim is to present average values and prevalence of electrocardiographic (ECG) abnormalities among the general Dutch population in the LifeLines Cohort. Hypothesis The ECG values previously studied in the Caucasian population of smaller cohorts will be confirmed with ECG data from LifeLines. Methods ECG data of 152 180 individuals age 18 to 93 years were available. Individuals with cardiovascular risk factors were excluded to analyze the healthy population. Average values of the ECG for the healthy population were presented as means with 95% and 99% confidence intervals and as medians with first and 99th percentiles. Results Median heart rate was highest in the youngest and oldest individuals of the healthy population. Median duration of P wave, PQ interval, and QRS duration were longer in males compared with females. In contrast, median QT interval corrected for heart rate was higher in females. In general, the above-mentioned parameters increased with age. The prevalences of ECG abnormalities adjusted for the Dutch population were 0.9% for atrial fibrillation or flutter, 1.4% for premature atrial complexes, 0.5% for myocardial infarction, 2.1% for ventricular premature complexes, 1.0% for left ventricular hypertrophy, 8.1% for P-R interval >200 ms, and 0.8% for bundle branch block. Conclusions Our study provides an overview of average values and ECG abnormalities and confirms data of previous smaller studies. In addition, we evaluate the age- and sex-dependent normal limits of the P wave and QRS duration and confirm in detail the frontal plane QRS-T angle on the ECG.