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QRS interval [keywords]
- Vectorcardiographic QRS area as a novel predictor of response to cardiac resynchronization therapy. [JOURNAL ARTICLE]
- J Electrocardiol 2014 Oct 24.
QRS duration and left bundle branch block (LBBB) morphology are used to select patients for cardiac resynchronization therapy (CRT). We investigated whether the area of the QRS complex (QRSAREA) on the 3-dimensional vectorcardiogram (VCG) can improve patient selection.VCG (Frank orthogonal lead system) was recorded prior to CRT device implantation in 81 consecutive patients. VCG parameters, including QRSAREA, were assessed, and compared to QRS duration and morphology. Three LBBB definitions were used, differing in requirement of mid-QRS notching. Responders to CRT (CRT-R) were defined as patients with ≥15% reduction in left ventricular end systolic volume after 6months of CRT.Fifty-seven patients (70%) were CRT-R. QRSAREA was larger in CRT-R than in CRT non-responders (140±42 vs 100±40 μVs, p<0.001) and predicted CRT response better than QRS duration (AUC 0.78 vs 0.62, p=0.030). With a 98μVs cutoff value, QRSAREA identified CRT-R with an odds ratio (OR) of 10.2 and a 95% confidence interval (CI) of 3.4 to 31.1. This OR was higher than that for QRS duration >156ms (OR=2.5; 95% CI 0.9 to 6.6), conventional LBBB classification (OR=5.5; 95% CI 0.9 to 32.4) or LBBB classification according to American guidelines (OR=4.5; 95% CI 1.6 to 12.6) or Strauss (OR=10.0; 95% CI 3.2 to 31.1).QRSAREA is an objective electrophysiological predictor of CRT response that performs at least as good as the most refined definition of LBBB.In 81 candidates for cardiac resynchronization therapy (CRT) we measured the area of the QRS complex (QRSAREA) using 3-dimensional vectorcardiography. QRSAREA was larger in echocardiographic responders than in non-responders and predicted CRT response better than QRS duration and than simple LBBB criteria. QRSAREA is a promising electrophysiological predictor of CRT response.
- Comparison of exercise electrocardiogram and exercise echocardiography in intermediate-risk chest pain patients. [Journal Article]
- Am J Emerg Med 2015 Jan; 33(1):7-13.
The novel exercise computer-assisted high-frequency QRS analysis (HF/QRS) has demonstrated improved sensitivity and specificity over the conventional ST/electrocardiogram-segment analysis (ST/ECG) in the detection of myocardial ischemia. The aim of the present study was to compare the diagnostic value of the validated exercise echocardiography (ex-Echo) with the novel exercise ECG (ex-ECG) including HF/QRS and ST/ECG analysis.A prospective cohort study was conducted in the emergency department of a tertiary care teaching Hospital. Patients with chest pain (CP), normal resting ECGs, troponins, and echocardiography, labeled as "intermediate-risk" for adverse coronary events, underwent the novel ex-ECG and ex-Echo. An ST-segment depression of at least 2 mV or at least 1 mV when associated with CP was considered as an index of ischemia, as well as a decrease of at least 50% in HF/QRS intensity, or new wall motion abnormalities on ex-Echo. Exclusion criteria were QRS duration of at least 120 milliseconds, poor echo-acoustic window, and inability to exercise. Patients were followed up to 3 months. The end point was the composite of coronary stenoses of 50% or greater at angiography or acute coronary syndrome, revascularization, and cardiovascular death on the 3-month follow-up.Of 188 patients enrolled, 18 achieved the end point. The novel ex-ECG and ex-Echo showed comparable negative predictive value (97% vs 96%; P = .930); however, sensitivity was 83% vs 61%, respectively (P = .612), and specificity was 64% vs 92%, respectively,(P = .026). The areas on receiver operating characteristic analysis were comparable (ex-ECG: 0.734 [95% confidence interval, or CI, 0.62-0.85] vs ex-Echo: 0.767 [CI, 0.63-0.91]; C statistic, P = .167). On multivariate analysis, both ex-ECG (hazard ratio, 5; CI, 1-20; P = .017) and ex-Echo (HR, 12; CI, 4-40; P < .001) were predictors of the end point.In intermediate-risk CP patients, the novel ex-ECG including HF/QRS added to ST/ECG analysis was a valuable diagnostic tool and might be proposed to avoid additional imaging. However, the novel test needs additional study before it can be recommended as a replacement for current techniques.
- Ventricular Arrhythmias in Super-responders to Cardiac Resynchronization Therapy. [Journal Article]
- Rev Esp Cardiol (Engl Ed) 2014 Nov; 67(11):883-9.
Cardiac resynchronization therapy is associated with improved quality of life and reduced morbidity and mortality in patients with severe ventricular dysfunction and wide QRS. However, its role in the reduction of ventricular arrhythmias is more controversial.We compared the incidence of ventricular arrhythmias in patients who were undergoing cardiac resynchronization therapy with an implantable cardioverter-defibrillator in terms of the degree of echocardiographic response to resynchronization. Patients were classified in 3 subgroups;super-responders, responders, and nonresponders.We included 196 patients who were followed up for a median 30.1 months [interquartile range, 18.0-55.1 months]. We recorded the presence of ventricular arrhythmias in 37 patients (18.8%); 3 patients (5.9%) in the super-responder group had ventricular arrhythmias vs 14 (22.2%) among the responders and 20 (24.4%) in the group of nonresponders (P = .025). In multivariate analysis, the only independent predictors of the appearance of ventricular arrhythmias were secondary-prevention device implantation (odds ratio = 4.04; 95% confidence interval, 1.52-10.75; P=.005), absence of echocardiographic super-response (odds ratio=3.81; 95% confidence interval, 1.04-13.93; P=043), QRS >160ms (odds ratio=2.39; 95% confidence interval, 1.00-1.35; P=.049) and treatment with amiodarone (odds ratio=2.47; 95% confidence interval, 1.03-5.91; P=.041).The patients classified as super-responders to cardiac resynchronization therapy had a significant reduction in incidence of ventricular arrhythmias by comparison with the other patients. Despite this, arrhythmic episodes do not completely disappear in this subgroup.
- Mechanisms of sex and age differences in ventricular repolarization in humans. [Journal Article]
- Am Heart J 2014 Nov; 168(5):749-756.e3.
Corrected QT interval (QTc) is shorter in postpubertal men than in women; however, QTc lengthens as men age and testosterone levels decrease. Animal studies have demonstrated that testosterone decreases L-type calcium current and increases slow delayed rectifier potassium current; however, it is not known how these contribute to QTc differences by sex and age in humans. We separately analyzed early versus late repolarization duration and performed simulations of the effect of testosterone on the electrocardiogram (ECG) to examine the mechanism of sex and age differences in QTc in humans.Twelve-lead ECGs from 2,235 healthy subjects (41% women) in Thorough QT studies were analyzed to characterize sex- and age-dependent differences in depolarization (QRS), early repolarization (J-Tpeak), and late repolarization (Tpeak-Tend). In addition, we simulated the effects of testosterone on calcium current, slow delayed rectifier potassium current, and surface ECG intervals.QTc was shorter in men than in women (394 ± 16 vs 408 ± 15 milliseconds, P < .001), which was due to shorter early repolarization (213 ± 16 vs 242 ± 16 milliseconds, P < .001), as men had longer depolarization (94 ± 7 vs 89 ± 7 milliseconds, P < .001) and longer late repolarization (87 ± 10 vs 78 ± 9 milliseconds, P < .001). Sex difference in QTc decreased with age and was due to changes in early repolarization. Simulations showed that the early repolarization changes were most influenced by testosterone's effect on calcium current.Shorter QTc in men compared to women is explained by shorter early repolarization, and this difference decreases with age. These sex and age differences in repolarization appear to be caused by testosterone effects on calcium current.
- Fragmented QRS is associated with frequency of premature ventricular contractions in patients without overt cardiac disease. [JOURNAL ARTICLE]
- Anadolu Kardiyol Derg 2014 Apr 8.
In this study, we aimed to demonstrate whether the presence of fragmented QRS (fQRS) is associated with the frequency of premature ventricular contractions (PVCs).We retrospectively analyzed 282 cases by 24-hour Holter monitorings (HMs) between August 2012 and February 2013. Firstly, the patients were divided into 2 groups with respect to presence of fQRS and then divided into 3 groups with respect to frequency of PVCs as Group 1: seldom PVC (<120 PVCs/day), Group 2: moderate-frequency PVC (120-720 PVCs/day), and Group 3: frequent PVC (>720 PVCs/day). We investigated the predictors of frequent PVCs by using multinomial logistic regression analysis.Ninety-eight patients had fQRS. There was no difference between the 2 groups with respect to body mass index, gender, hypertension, and diabetes mellitus. Patients with fQRS were older (54.9±15.6 vs. 47.0±16.3, p<0.001) and had more family history of coronary artery disease (25% vs. 13%, p=0.012). Patients with fQRS was more likely to be on aspirin therapy (28.6% vs 10.4%, p<0.001) and have a larger left atrium diameter (33.5±5.7 vs. 30.4±5.8, p=0.001). Presence of fQRS was significantly associated with the frequency of PVCs (for frequent PVC 27.7% vs. 7.6%, p<0.001; for moderate-frequency PVC 18.4% vs. 11.4%, p=0.012); 26.2% of Group 1 (n=202) had fQRS, 46.2% of Group 2 (n=39) had fQRS, and 65.9% of Group 3 (n=41) had fQRS. In the multinomial regression analysis, only age (odds ratio: 4.24, 95% confidence interval 2.08-8.64, p=0.001) and fQRS (odds ratio: 2.11, 95% confidence interval 1.00-4.45, p=0.05) were predictors of frequent PVCs.This study demonstrated that the presence of fQRS is associated with frequent PVCs in patients without overt structural heart disease.
- Electrophysiologic Characteristics of Ventricular Arrhythmias Arising From the Aortic Mitral Continuity - Potential Role of the Conduction System. [JOURNAL ARTICLE]
- J Cardiovasc Electrophysiol 2014 Nov 26.
Catheter ablation of ventricular arrhythmia (VA) at the fibrous aortic mitral continuity (AMC) has been described, yet the nature of the arrhythmogenic substrate remains unknown.Procedural records of 528 consecutive patients undergoing ablation of VA at Mayo Clinic, Rochester, MN, were reviewed. The electrocardiographic and electrophysiologic characteristics of patients with successful ablation at the AMC were analyzed to characterize the underlying arrhythmogenic substrate.Of the 21 patients (mean age 53.2 ± 13.4 years, 47.6% male) who underwent ablation of VA at the AMC with acute success, prepotentials (PPs) were found at the ablation sites preceding the ventricular electrogram (VEGM) during arrhythmias in 13 (61.9%) patients and during sinus rhythm in 7 (53.8%) patients. VAs with PPs were associated with a significantly higher burden of premature ventricular complexes (PVCs) (26.1 ± 10.9% vs 14.9 ± 10.1%, p = 0.03), shorter VEGM to QRS intervals (9.0 ± 28.5 ms vs 33.1 ± 8.8 ms, p = 0.03), lower pace map scores (8.7 ± 1.6 vs 11.4 ± 0.8, p = 0.001), and a trend towards shorter V-H intervals during VA (32.1 ± 38.6 ms vs 76.3 ± 11.1 ms, p = 0.06) as compared to those without PP. A strong and positive correlation was found between V-H interval and QRS duration during arrhythmia in those with PPs (B = 2.11, R(2) = 0.97, t = 13.7, p <0.001) but not in those without PPs.Local EGM characteristics and relative activation time of the His bundle suggest the possibility of conduction tissue as the origin for VA arising from the fibrous AMC. Specific identification and targeting of PPs when ablating VAs at this location may improve procedural success. This article is protected by copyright. All rights reserved.
- Relationship between Neutrophil-To-Lymphocyte Ratio and Electrocardiographic Ischemia Grade in STEMI. [JOURNAL ARTICLE]
- Arq Bras Cardiol 2014 Nov 21.
Background:Neutrophil-to-lymphocyte ratio (NLR) has been found to be a good predictor of future adverse cardiovascular outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Changes in the QRS terminal portion have also been associated with adverse outcomes following STEMI.
Objective:To investigate the relationship between ECG ischemia grade and NLR in patients presenting with STEMI, in order to determine additional conventional risk factors for early risk stratification.
Methods:Patients with STEMI were investigated. The grade of ischemia was analyzed from the ECG performed on admission. White blood cells and subtypes were measured as part of the automated complete blood count (CBC) analysis. Patients were classified into two groups according to the ischemia grade presented on the admission ECG, as grade 2 ischemia (G2I) and grade 3 ischemia (G3I).
Results:Patients with G3I had significantly lower mean left ventricular ejection fraction than those in G2I (44.58 ± 7.23 vs. 48.44 ± 7.61, p = 0.001). As expected, in-hospital mortality rate increased proportionally with the increase in ischemia grade (p = 0.036). There were significant differences in percentage of lymphocytes (p = 0.010) and percentage of neutrophils (p = 0.004), and therefore, NLR was significantly different between G2I and G3I patients (p < 0.001). Multivariate logistic regression analysis revealed that only NLR was the independent variable with a significant effect on ECG ischemia grade (odds ratio = 1.254, 95% confidence interval 1.120-1.403, p < 0.001).
Conclusion:We found an association between G3I and elevated NLR in patients with STEMI. We believe that such an association might provide an additional prognostic value for risk stratification in patients with STEMI when combined with standardized risk scores.
- Multiple manifested accessory atrioventricular pathways in a patient without obvious structural heart disease. [JOURNAL ARTICLE]
- J Cardiovasc Electrophysiol 2014 Nov 24.
A 53-year-old man was referred for treatment of pre-excitation syndrome, which was first diagnosed after having had cardioversion for pre-syncope due to atrial fibrillation. He had hypertension controlled with losantan. The ECG indicated multiple accessory pathways (APs), located on the tricuspid annulus (TVA). Echocardiography revealed a dilated left atrium and slight left ventricular hypertrophy (associated with hypertension) without Ebstein anomaly. The procedure was performed with a 3D mapping system (CARTO 3). Manifested APs were mapped and ablated at 8 o'clock, 6 o'clock and 4 o'clock on the TVA step by step with a 4-mm-tip catheter (Fig 1, TA 1-3). However, an irrigation ablation catheter was mandatory for the AP at 4 o'clock due to the limitation of power output by a slight diverticulum. A normal QRS wave was achieved after ablation of the fourth AP at 2 o'clock on the TVA (Fig 1, TA4). The fifth AP was unmasked by isoproterenol infusion and was abolished at 10 o'clock on the TVA (Fig 1, TA5). After a 40-minute observation period, the procedure was stopped. Unfortunately, pre-excitation reappeared 9 hours after the procedure. In the repeat procedure (1 month later), the recurrent AP was mapped and ablated at 10 o'clock on the TVA. Six months after the repeated procedure, the patient still had a normal QRS without pre-excitation. For multiple APs, it is important to recognize the possibility of multiple APs before procedure and to pay attention to the change of ECG morphology and the local A-V interval or conduction during operation. With the help of a 3D mapping system, it would be feasible to precisely identify the location of multiple APs. This article is protected by copyright. All rights reserved.
- The Predictive Value of Admission Fragmented QRS Complex for In-Hospital Cardiovascular Mortality of Patients with Type 1 Acute Aortic Dissection. [JOURNAL ARTICLE]
- Ann Noninvasive Electrocardiol 2014 Nov 23.
Fragmented QRS (fQRS) arises from impaired ventricular depolarization due to heterogeneous electrical activation of ischemic and/or infarcted ventricular myocardium. The short- and long-term prognostic values of fQRS have been reported for myocardial infarction, heart failure, fatal cardiac arrhythmias, and sudden cardiac death. The aim of this study was to investigate the predictive value of admission fQRS complex for in-hospital cardiovascular mortality of patients with type 1 acute aortic dissection (AAD).In this retrospective study, 203 consecutive patients with type 1 AAD who had been admitted to either of two large-volume tertiary hospitals between December 2008 and October 2013 were included. The patients were divided into two groups according to the presence or absence of the fQRS complex on admission.In-hospital cardiovascular mortality (P < 0.001), major adverse cardiovascular events (P < 0.001), acute renal failure (P = 0.022), multiorgan dysfunction (P < 0.001), and acute decompensated heart failure (P < 0.001) were observed to be significantly more frequent in the fQRS-positive group than in the fQRS-negative group. fQRS (odds ratio [95% confidence interval]: 4.184 [1.927-9.082], P < 0.001), operation duration (4.184 [1.927-9.082], P = 0.001), and Killip class IV (3.900 [1.699-8.955], P = 0.001) were found to be significant independent predictors of in-hospital cardiovascular mortality after adjustment of other risk factors in the multivariate analysis.fQRS is a simple, inexpensive, and readily available electrocardiographic entity that provides an additional risk stratification level beyond that provided by conventional risk parameters in predicting in-hospital cardiovascular mortality in type 1 AAD.
- Outcome of prolonged QRS interval in dilated cardiomyopathy: role of implantable cardioverter-defibrillators on mortality. [JOURNAL ARTICLE]
- Ther Adv Cardiovasc Dis 2014 Nov 18.
The main objectives of this study were to investigate the relationship between prolonged QRS interval and its prognosis in patients with dilated cardiomyopathy (DCM), and to determine the effects of cardiac pacing with an implantable cardioverter-defibrillator (ICD) on mortality in patients with a QRS width > 150 ms.We retrospectively queried the healthcare enterprise data warehouse and the patient medical records from January 2007 to December 2012 for 1453 cases of DCM at a university- affiliated hospital. Of the 1453 cases, 989 patients were included in the final analyses. Primary outcome variable was all-cause mortality.Of the 989 patients, 20% (n = 198) of the patients had a QRS width > 150 ms. Compared with patients who had a QRS < 120 ms, patients with a QRS > 150 ms had significantly higher rates of death (p < 0.001). Among the subgroup of 198 patients who had a QRS width > 150 ms, survival (84.3%, n = 75) was significantly higher (p < 0.001) in patients with a pacemaker inserted compared with those (45.0%, n = 49) who had not been paced.Prolonged QRS interval is significantly associated with a higher rate of mortality. However, we believe that cardiac pacing with an ICD in such patients can significantly improve outcomes.