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QRS interval [keywords]
- How can computerized interpretation algorithms adapt to gender/age differences in ECG measurements? [JOURNAL ARTICLE]
- J Electrocardiol 2014 Aug 7.
It is well known that there are gender differences in 12 lead ECG measurements, some of which can be statistically significant. It is also an accepted practice that we should consider those differences when we interpret ECGs, by either a human overreader or a computerized algorithm. There are some major gender differences in 12 lead ECG measurements based on automatic algorithms, including global measurements such as heart rate, QRS duration, QT interval, and lead-by-lead measurements like QRS amplitude, ST level, etc. The interpretation criteria used in the automatic algorithms can be adapted to the gender differences in the measurements. The analysis of a group of 1339 patients with acute inferior MI showed that for patients under age 60, women had lower ST elevations at the J point in lead II than men (57±91μV vs. 86±117μV, p<0.02). This trend was reversed for patients over age 60 (lead aVF: 102±126μV vs. 84±117μV, p<0.04; lead III: 130±146μV vs. 103±131μV, p<0.007). Therefore, the ST elevation thresholds were set based on available gender and age information, which resulted in 25% relative sensitivity improvement for women under age 60, while maintaining a high specificity of 98%. Similar analyses were done for prolonged QT interval and LVH cases. The paper uses several design examples to demonstrate (1) how to design a gender-specific algorithm, and (2) how to design a robust ECG interpretation algorithm which relies less on absolute threshold-based criteria and is instead more reliant on overall morphology features, which are especially important when gender information is unavailable for automatic analysis.
- Cardiac-resynchronization therapy in patients with systolic heart failure and QRS interval ≤130 ms: insights from a meta-analysis. [JOURNAL ARTICLE]
- Europace 2014 Aug 27.
Cardiac-resynchronization therapy (CRT) reduces morbidity and mortality in patients with chronic systolic heart failure (SHF) and a wide QRS complex. It is unclear whether the same benefit extends to patients with QRS duration (QRSd) <130 ms.Our aim was to perform a meta-analysis of all randomized controlled trial (RCTs) and to evaluate the effect of implantable CRT defibrillator(CRTD) on all-cause mortality, HF mortality, and HF hospitalization in patients with QRSd <130 ms. We performed a systematic literature search to identify all RCTs, comparing CRTD therapy with implantable cardiac defibrillator (ICD) therapy in patients with SHF (ejection fraction <35%) and QRS ≤130 ms, published in Pubmed, Medline, EMBASE, Cochrane library, and Google scholar from June 1980 through June 2013. The search terms included CRT, QRS duration, narrow QRS, clinical trial, RCT, biventricular pacing, heart failure, systolic dysfunction, dyssynchrony, left ventricular remodelling, readmission, mortality, survival, and various combinations of these terms. We studied the trends of overall mortality, SHF mortality, and hospitalizations due to SHF between the two groups. Heterogeneity of the studies was analysed by Q statistic. A fixed-effect model was used to compute the relative risk (RR) of mortality due to SHF, while a random-effects model was used to compare hospitalization due to SHF. Out of a total of 12 100 citations, four RCTs comparing CRTD vs. ICD therapy in patients with SHF and QRS ≤130 ms fulfilled the inclusion criteria. The median follow-up was 12 months and the cumulative number of patients was 1177. Relative Risk for all-cause mortality in patients treated with CRTD was 1.66 with a 95% CI of 1.096-2.515 (P = 0.017) while for SHF mortality was 1.29 with 95% CI of 0.68-2.45 (P = 0.42). Relative risk for HF hospitalization in patients treated with CRTD was 0.94 with 95% CI of 0.50-1.74 (P = 0.84) in comparison to the ICD group.Cardiac-resynchronization therapy defibrillator has no impact on SHF mortality and SHF hospitalization in patients with systolic HF with QRS duration ≤130 ms and is associated with higher all-cause mortality in comparison with ICD therapy.
- Clinical outcome as a function of the PR-interval-there is virtue in moderation: data from the Duke Databank for cardiovascular disease. [JOURNAL ARTICLE]
- Europace 2014 Aug 27.
Recently, a U-shaped association between PR-interval and the risk of developing atrial fibrillation was described, with higher risk in patients with long and short PR-intervals. Little is known regarding the association of PR-interval duration and mortality. The objective of the current study was to explore the relationship between PR-interval and major cardiovascular outcomes in patients with known coronary heart disease.Patients in sinus rhythm, undergoing coronary angiography at Duke University Medical Center between 1989 and 2010, who had significant stenosis in at least one native coronary artery, were included. Patients with arrhythmia, second- or third-degree AV-block, QRS > 120 ms were excluded. A total of 9,637 patients were included (median age 63, IQR 55-71 years, 67% men). After adjustment for relevant covariates, the risk of a CV event increased with a decreasing PR-interval (10 ms decrements) for PR-interval values <162 ms (all-cause mortality; HR 1.057, 95% CI 1.019-1.096, P = 0.0030, composite of death or stroke; HR 1.047, 95% CI 1.011-1.085, P = 0.0095 and composite of cardiovascular death or cardiovascular rehospitalization; HR 1.032, 95% CI 1.002-1.063, P = 0.0387). No statistically significant changes in the risk associated with PR-interval for values >162 ms were seen for any of the studied endpoints.In patients with coronary heart disease, a prolongation of the PR-interval was not independently associated with poor outcomes, but a PR-interval shorter than normal was associated with increased all-cause mortality and other major cardiovascular events.
- [The characteristics of RR-Lorenz plot in persistent atrial fibrillation patients complicating with escape beats and rhythm]. [English Abstract, Journal Article]
- Zhonghua Xin Xue Guan Bing Za Zhi 2014 Jun; 42(6):481-3.
To explore the characteristics of RR-Lorenz plot in persistent atrial fibrillation (AF) patients complicating with escape beats and rhythm though ambulatory electrocardiogram.The 24-hour ambulatory electrocardiogram of 291 persistent AF patients in second affiliated hospital of Zhengzhou university from July 2005 to April 2013 were retrospectively analyzed and the RR interval and the QRS wave were measured. Patients were divided into two groups according to the distribution of the RR-Lorenz point [AF without escape beats and rhythm group (Group A, n = 259) and AF with escape beats and rhythm group (Group B, n = 32)]. The characteristics of RR-Lorenz plot between the two groups were compared.(1) Fan-shaped RR-Lorenz plots were evidenced in Group A. (2)In Group B, 30 cases showed fan-shaped with L-shaped and a short dense rods along 45° line. The proportion of escape beats and rhythm was 0.28% (275/98 369) -14.06% (11 263/80 112) . The other 2 cases in group B showed no typical RR-Lorenz plots features.RR-Lorenz plot could help to quickly diagnose persistent AF complicating with escape beats and rhythm according to the typical RR-Lorenz plot characteristics in 24-hour ambulatory electrocardiogram.
- Fragmented QRS may predict increased arterial stiffness in asymptomatic hypertensive patients. [JOURNAL ARTICLE]
- Blood Press Monit 2014 Aug 26.
Detection of increased arterial stiffness could prevent patients from being mistakenly classified as being at a low or a moderate risk, when they actually are at a high risk. The main aim of present study was to investigate the relation between fragmented QRS (fQRS) on ECG and the cardio-ankle vascular index (CAVI), which is a novel parameter of arterial stiffness in asymptomatic hypertensive patients.Seventy-five asymptomatic hypertensive patients with fQRS and 75 age-matched and sex-matched control individuals without fQRS were enrolled. Patients with fQRS had higher CAVI values compared with those without fQRS (8.6±1.4 vs. 7.9±1.3, P=0.01). In univariate analyses, there was a significant association between increased CAVI and age (P<0.001) and fQRS (P=0.003). Multivariate binary logistic regression analyses showed fQRS (95% confidence interval: 0.122-0.675, P=0.004) and age (95% confidence interval: 1.022-1.105, P=0.002) as the independent determinants of increased CAVI. The sensitivity and specificity of fQRS for predicting abnormal CAVI were 55 and 76%, respectively.The presence of fQRS on ECG may provide important predictive information on arterial stiffness in asymptomatic hypertensive patients.
- Effects of Atrioventricular Nodal Ablation on Permanent Atrial Fibrillation Patients With Cardiac Resynchronization Therapy: A Systematic Review and Meta-analysis. [JOURNAL ARTICLE]
- Clin Cardiol 2014 Aug 25.
Cardiac resynchronization therapy (CRT) is a well-established therapy for patients with heart failure (HF) and wide QRS configuration, especially for those in sinus rhythm. However, for those with permanent AF, atrioventricular nodal (AVN) ablation use remains under debate. Our objective was to evaluate clinical outcomes and mortality of AVN ablation in HF patients with permanent AF receiving CRT. Electronic publication database and reference lists through October 1, 2013 were searched. Observational cohort studies comparing CRT patients with AF who received either AVN ablation or medical therapy were selected. Outcomes included mortality, CRT nonresponse, changes in left ventricular remodeling, and functional outcomes, such as New York Heart Association (NYHA) functional class, quality of life, and 6-minute hall walk distance. Of 1641 reports identified, 13 studies with 1256 patients were included. Among patients with permanent AF and insufficient biventricular pacing (<90%), those who had undergone AVN ablation compared to those who did not had numerically lower all-cause mortality (risk ratio [RR]: 0.63, 95% confidence interval [CI]: 0.42 to 0.96, P = 0.03) and significantly lower nonresponse to CRT (RR: 0.41, 95% CI: 0.31 to 0.54, P < 0.00001). Furthermore, AVN ablation was not associated with additional improvements on left ventricular ejection fraction, NYHA functional class, 6-minute hall walking distance, and quality of life. In patients with permanent AF undergoing CRT, AVN ablation tended to reduce mortality potentially and improved clinical response when it was applied to patients with inadequate biventricular pacing (<90%). Randomized controlled trials are needed to further address the efficacy of AVN ablation among this population.
- Comparison of three ECG criteria for athlete pre-participation screening. [JOURNAL ARTICLE]
- J Electrocardiol 2014 Aug 2.
Controversy regarding adding the ECG to the evaluation of young athletes centers on the implications of false positives. Several guidelines have been published with recommendations for criteria to distinguish between ECG manifestations of training and markers of risk for cardiovascular (CV) sudden death. With an athlete dataset negative of any CV related abnormalities on follow-up, we applied three athlete screening criteria to identify the one with the lowest rate of abnormal variants.High school, college, and professional athletes underwent 12L ECGs as part of routine physicals. All ECGs were recorded and processed using CardeaScreen (Seattle, WA). The European (2010), Stanford (2011), and Seattle criteria (2013) were applied.From March 2011 to February 2013 1417 ECGs were collected. Mean age was 20±4years (14-35years), 36% female, 38.5% non-white (307 high school, 836 college and 284 professional). Rate of abnormal variants differed by criteria, predominately due to variation in interval thresholds for QT interval and QRS duration. There was a four-fold difference in abnormal variants between European and Seattle criteria (26% v 6%).The Seattle criterion was the most conservative resulting in 78% fewer abnormal variants than the European criteria. Variation was most evident with thresholds for QT prolongation, short QT interval, and intraventricular conduction delay. Continued research is needed to further understand normal training related adaptations and to improve modern ECG screening criteria for athletes.
- Comparison of the therapeutic effect between sodium bicarbonate and insulin on acute propafenone toxicity. [JOURNAL ARTICLE]
- Am J Emerg Med 2014 Jul 30.
Unlike other sodium-channel-blocking antiarrhythmic agents, propafenone has β-blocking effects and calcium-channel-blocking effects. Yi et al recently studied insulin's treatment effect on acute propafenone toxicity in rats. However, because the degree of effectiveness of insulin compared to the previously known antidote sodium bicarbonate (NaHCO3) was not studied, the 2 treatment methods were compared for propafenone intoxication in rats.Rats received intravenous propafenone (36 mg/[kg h]) for 12 minutes. After the induction of toxicity, rats (n = 10 per group) received normal saline solution (NSS), NaHCO3, or insulin with glucose as treatment. Animals in the NSS, NaHCO3, and Insulin groups received an intravenous infusion of 36 mg/(kg h) propafenone until death occurred. For each animal, the mean arterial pressure (MAP, heart rate, PR interval, QRS duration, total hemoglobin, sodium, potassium, potential of hydrogen, bicarbonate, glucose, lactate, and central venous oxygen saturation (Scvo2) were measured and compared among the groups.Survival of the Insulin group was greater than that of the NSS group by log-rank test (P = .021). Sodium bicarbonate prevented the decline of MAP for 55 minutes. In comparison, insulin prevented the decline of MAP and heart rate, and the elongation of the PR interval and QRS duration for 55 minutes (P < .05). Propafenone toxicity led to decreased Ca(2+), potential of hydrogen, and Scvo2 and increased lactate levels. Insulin prevented the decrease of Ca(2+) and Scvo2, whereas NaHCO3 prevented the increase in lactate.Insulin treatment was more effective than NaHCO3 on acute propafenone toxicity in rat. Therefore, when propafenone-induced cardiotoxicity occurs, which is unresponsive to current treatment methods, glucose-insulin infusion may be considered.
- A new formula for the evaluation of the QT-interval in patients with left bundle branch block. [JOURNAL ARTICLE]
- Heart Rhythm 2014 Aug 19.
Left-bundle-branch-block(LBBB) and QT-prolongation are both associated with a worse prognosis. LBBB lengthens the QT-interval. So far it is not known if QT-time prolongation during LBBB differs in repolarization from QT-time prolongation during narrow QRS.The aim of the present proof-of-concept-study is therefore to develop a formula that allows to compare the adjusted QT-interval during LBBB with reference values and thereby allow interpretation of the QT-interval irrespective of the QRS-widening.60 consecutive patients with sinus-rhythm(SR) and narrow-QRS underwent an EP-study for ablation. In all patients the intrinsic QRS-,QT- and JT-time was measured during SR and ventricular-pacing from the right-ventricular-apex(RVA) and outflow-tract(RVOT) both causing a LBBB. We determined the prolongation of the QT during as compared to SR(ΔQT). ΔQT was then divided by the QRS-length during paced-QRS(QRSb). This describes the percentage of the QRS-duration at LBBB, which must be subtracted from the measured QT(QTb), to determine the modified-QT(QTm).The ratio of ΔQT to paced-QRS was calculated as 48,3%(RVA) and 48.8%(RVOT)[mean 48.5%]. The ratio intrinsic-JTi to paced-JT was 1.0055 (RVA) and 1.0087(RVOT). There was no significant difference in intrinsic-JT vs. paced-JT(p=0.2) CONCLUSION: Right-ventricular-pacing causes a prolongation of the QT due to a paced-LBBB without prolongation of the JT-time. In our study, we have shown that the QT-prolongation caused by the LBBB amounts 48.5% of the QRS-width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified-QT. The resulting Formula for "modified-QT" estimation in LBBB is: QTm = QTb - 48,5%*(QRSb).
- Echocardiographic and clinical response to cardiac resynchronization therapy in heart failure patients with and without previous right ventricular pacing. [JOURNAL ARTICLE]
- Eur J Heart Fail 2014 Jul 31.
Right ventricular pacing (RVp) results in an electrocardiographic left bundle branch block pattern and can lead to heart failure. This study aimed to evaluate echocardiographic and clinical outcomes of heart failure patients with RVp upgraded to cardiac resynchronization therapy (CRT), as they are frequently excluded from multicentre studies.This observational study assessed 655 consecutive patients with QRS ≥120 ms and left ventricular ejection fraction ≤35%. There were 465 patients without significant previous RVp and 190 with RVp >40%. Echocardiograms were analysed pre-CRT and ∼ 1 year post-CRT. Death and heart failure hospitalizations were analysed using Cox regression, adjusted for baseline characteristics. The RVp patients had smaller end-systolic volume (P = 0.002), were older (P < 0.001), and had more atrial fibrillation (P < 0.001) pre-CRT. Ejection fraction and proportion of ischaemic aetiology were similar. One year following CRT implantation the ejection fraction response was greater in the RVp group (8.3 ± 9 vs. 5.8 ± 9 units, P = 0.005). The RVp patients had an adjusted 33% lower risk of death or heart failure hospitalization [hazard ratio (HR) 0.67 95% confidence interval (CI) 0.51-0.89, P = 0.005], while tending to have an adjusted lower risk of death (HR 0.73 95% CI 0.53-1.01, P = 0.055).Despite similar ejection fraction pre-CRT, patients upgraded to CRT with previous RVp have smaller end-systolic volume and respond to CRT at least as well as, if not better than, other wide QRS heart failure patients. A greater improvement in ejection fraction and a lower risk of death or heart failure hospitalization when adjusted for baseline characteristics were seen in those with previous RVp.