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QRS interval [keywords]
- β-Adrenergic blockade combined with subcutaneous B-type natriuretic peptide: a promising approach to reduce ventricular arrhythmia in heart failure? [JOURNAL ARTICLE]
- Heart 2014 Mar 25.
Clinical studies failed to prove convincingly efficiency of intravenous infusion of neseritide during heart failure and evidence suggested a pro-adrenergic action of B-type natriuretic peptide (BNP). However, subcutaneous BNP therapy was recently proposed in heart failure, thus raising new perspectives over what was considered as a promising treatment. We tested the efficiency of a combination of oral β1-adrenergic receptor blocker metoprolol and subcutaneous BNP infusion in decompensated heart failure.The effects of metoprolol or/and BNP were studied on cardiac remodelling, excitation-contraction coupling and arrhythmias in an experimental mouse model of ischaemic heart failure following postmyocardial infarction. We determined the cellular and molecular mechanisms involved in anti-remodelling and antiarrhythmic actions. As major findings, the combination was more effective than metoprolol alone in reversing cardiac remodelling and preventing ventricular arrhythmia. The association of the two molecules improved cardiac function, reduced hypertrophy and fibrosis, and corrected the heart rate, sympatho-vagal balance (low frequencies/high frequencies) and ECG parameters (P to R wave interval (PR), QRS duration, QTc intervals). It also improved altered Ca(2+) cycling by normalising Ca(2+)-handling protein levels (S100A1, SERCA2a, RyR2), and prevented pro-arrhythmogenic Ca(2+) waves derived from abnormal Ca(2+) sparks in ventricular cardiomyocytes. Altogether these effects accounted for decreased occurrence of ventricular arrhythmias.Association of subcutaneous BNP and oral metoprolol appeared to be more effective than metoprolol alone. Breaking the deleterious loop linking BNP and sympathetic overdrive in heart failure could unmask the efficiency of BNP against deleterious damages in heart failure and bring a new potential approach against lethal arrhythmia during heart failure.
- Coupling Interval Variability Differentiates Ventricular Ectopic Complexes Arising in the Aortic Sinus of Valsalva and Great Cardiac Vein From Other Sources: Mechanistic and Arrhythmic Risk Implications. [JOURNAL ARTICLE]
- J Am Coll Cardiol 2014 Mar 5.
The objective of this study was to determine whether premature ventricular contractions (PVCs) arising from the aortic sinuses of Valsalva (SOV) and great cardiac vein (GCV) have coupling interval (CI) characteristics that differentiate them from other ectopic foci.PVCs occur at relatively fixed CI from the preceding normal QRS in most patients. However, we observed patients with PVCs originating in unusual areas (SOV and GCV) in whom the PVC CI was highly variable. We hypothesized that PVCs from these areas occur seemingly randomly due to lack of electrotonic effects of surrounding myocardium.73 consecutive patients referred for PVC ablation were assessed. Twelve consecutive PVC coupling intervals were recorded. The ΔCI (max-min CI) was measured.We studied 73 patients (age 50±16 years, 47% male). PVC origin was right ventricular (RV) in 29 (40%), left ventricular (LV) in 17 (23%), SOV 21 (29%) and GCV in 6 (8%). There was a significant difference between the mean ΔCI of RV/LV compared to SOV/GCV PVCs (33±15 ms vs 116±52 ms, p<0.0001). A ΔCI of>60 ms demonstrated a sensitivity of 89%, specificity of 100%, positive predictive value of 100% and negative predictive value of 94%. Cardiac events were more common in the SOV/GCV vs the RV/LV group (7/27 [26%] vs 2/46 [4%], p<0.02).ΔCI is more pronounced in PVCs originating from the SOV or GCV. ΔCI of 60 ms helps discriminate the origin of PVCs prior to diagnostic electrophysiologic study and may be associated with increased frequency of cardiac events.
- Electrocardiographic Findings in Takotsubo Cardiomyopathy: ECG Evolution and Its Difference from the ECG of Acute Coronary Syndrome. [Journal Article]
- Clin Med Insights Cardiol 2014.:29-34.
Electrocardiogram (ECG) manifestations of takotsubo cardiomyopathy (TC) produce ST-segment elevation or T-wave inversion, mimicking acute coronary syndrome (ACS). We describe the ECG manifestation of TC, including ECG evolution, and its different points from ACS.We studied 37 consecutive patients (age 67 ± 15 years, range 23-89, M:F = 12:25) from March 2004 to November 2012 with a diagnosis of TC who were proven to have apical ballooning on echocardiography or left ventricular angiography and normal coronary artery. We analyzed their standard 12-lead ECGs, including rate, PR interval, QRS duration, corrected QT (QTc) interval, ECG evolutions, and arrhythmia events.Two common ECG findings in TC were ST-segment elevation (n = 13, 35%) and T inversion (n = 24, 65%), mostly in the precordial leads. After ST-segment resolution, in a few days (3.5 days), diffuse and often deep T-wave inversion developed. Eight patients (22%) had transient Q-waves lasting a few days in precordial leads. No reciprocal ST-segment depression was noted. T-wave inversion continued for several months. QT prolongation (<440 milliseconds) was observed in 37 patients (97%). There were no significant life-threatening arrhythmias except atrial fibrillation (n = 6, 16%).There are distinct differences between the ECGs of TC and ACS. These differences will help to differentiate TC from ACS.
- [The influence of intravenous ozone therapy on the electrophysiological properties of myocardium during combined treatment of the patients presenting with arterial hypertension]. [English Abstract, Journal Article]
- Vopr Kurortol Fizioter Lech Fiz Kult 2013 Nov-Dec; (6):48-51.
The present investigation included 65 patients (36 men and 29 women of the mean age of 51.3 +/- 6.7 years) presenting with grade I-II arterial hypertension (AH) and undergoing intravenous ozone therapy in combination with the intake of antihypertensive preparations. ECG studies showed that a course of ozone therapy decreases the degree of in homogeneity of intra-myocardial electrophysiological processes in the patients with AH as apparent from reduced dispersion of P-wave and corrected QT-interval. Analysis of the results of high-resolution ECG revealed a significant decrease in the frequency of ventricular late potentials from 29.2% (19 patients) to 13.8% (9 patients) (chi2=4.5; p=0.03) whereas the decrease in the frequency of atrial late potentials was insignificant, from 40% (26 patients) to 29.2% (19 patients) (chi2=1.67; p=0.19). The results of spectral-temporal mapping indicate that a course of ozone therapy resulted in a significant decrease of the total number of local peaks in the QRS complex and the number of peaks with low-amplitude and high-frequency characteristics.
- Electrocardiographic characteristics of premature ventricular contractions in subjects with type 1 pattern of Brugada syndrome. [JOURNAL ARTICLE]
- J Electrocardiol 2014 Mar 2.
The ECG characteristics of premature ventricular contractions (PVCs) in subjects with Brugada syndrome (BrS) phenotype were investigated.A total of 96 patients with type 1 ECG pattern of BrS were screened for PVCs. The study population consisted of 10 male individuals (mean age 41.9±5.6years) with spontaneous (n=2) or drug-induced (n=8) type 1 ECG phenotype of BrS and PVCs. Twenty patients (11 males, age 44.6±15.1years) with idiopathic right ventricular outflow tract (RVOT) PVCs (LBBB/inferior axis morphology with a negative QRS complex in lead aVL) successfully ablated from an endocardial site were also included in the study, and served as comparative controls. Six subjects with BrS phenotype (five during drug challenge) displayed PVCs with LBBB/inferior axis morphology and negative QRS complex in aVL lead which indicates an RVOT origin. The ECG characteristics of PVCs with LBBB/inferior axis in subjects with BrS and idiopathic RVOT arrhythmia were subsequently compared. QRS duration in inferior (p=0.001) and right precordial leads (p<0.001) was significantly longer in subjects with BrS phenotype. The RS interval in lead V2 was also significantly prolonged in individuals with BrS phenotype (p=0.016). Subjects with BrS phenotype exhibited an increased intrinsicoid deflection time measured in right precordial leads compared to those with idiopathic RVOT PVCs (46.0±7.6 vs. 27.2±9.5ms, p<0.001). Finally, a pseudo-delta wave in precordial leads was more commonly observed in subjects with BrS ECG pattern (p=0.029).PVCs in BrS usually originate from the RVOT and display specific ECG characteristics that might be indicative of an epicardial origin. The prolonged interval criteria may be related to a localized epicardial conduction delay.
- Risk of Mortality in Individuals With Low QRS Voltage and Free of Cardiovascular Disease. [Journal Article]
- Am J Cardiol 2014 May 1; 113(9):1514-7.
The prognostic significance of low QRS voltage (LQRSV) in the electrocardiogram (ECG) of individuals free of cardiovascular disease (CVD) is unclear. We evaluated the association between LQRSV and all-cause mortality in 6,440 participants (53% women, mean age 60 years) from the Third National Health and Nutrition Examination Survey, a representative sample of the US population. Participants with history of CVD or major ECG abnormalities were excluded. LQRSV was automatically defined from standard 12-lead ECG as QRS complex amplitudes of <0.5 mV in all frontal leads and/or <1.0 mV in all precordial leads. Mortality data through 2006 were obtained from National Death Index records. LQRSV was detected in 1.4% (n = 89) of the participants. During a median follow-up of 13.8 years, 2,000 deaths occurred. The mortality rate in individuals with LQRSV was almost twice that in those without LQRSV (51.1 vs 23.5 events per 1,000 person-years, p <0.01). In a demographic-adjusted model, LQRSV was associated with 63% increased risk of mortality (hazard ratio 1.63, 95% confidence interval [1.21, 2.18]). The magnitude of this risk did not appreciably change after additional adjustment for body mass index, smoking status, systolic blood pressure, blood pressure medication use, dyslipidemia, diabetes, cancer, pulmonary disease, and ECG abnormalities (hazard ratio 1.61, 95% confidence interval [1.20, 2.16]) and was consistent across age, race, and sex subcategories. In conclusion, LQRSV is associated with an increased risk of mortality in individuals free of apparent CVD. More research is warranted to determine the mechanisms by which LQRSV is associated with increased risk of mortality in apparently healthy individuals.
- Left bundle branch block predicts better survival in women than men receiving cardiac resynchronization therapy: long-term follow-up of ∼145,000 patients. [Journal Article]
- JACC Heart Fail 2013 Jun; 1(3):237-44.
The goal of this study was to test the hypothesis that in recipients of cardiac resynchronization therapy defibrillators (CRT-D), conventional left bundle branch block (LBBB) diagnosis predicts better survival in women than in men.New York Heart Association class I and II patients without LBBB do not benefit from CRT-D, and women have better survival after CRT-D than men. Separate analysis suggests that QRS duration thresholds for LBBB diagnosis differ according to sex, and conventional LBBB electrocardiographic criteria are falsely positive in men more frequently than in women.We analyzed Medicare records from 144,642 CRT-D recipients between 2002 and 2008 that were followed up for up to 90 months. Medicare billing data were used to determine age, sex, race, and comorbidities. Hazard ratios (HRs) were calculated to assess if conventional LBBB diagnosis had different prognostic significance according to sex.In univariate analysis, LBBB was associated with a 31% reduction in death in women (HR: 0.69 [95% confidence interval (CI): 0.67 to 0.71]) but only a 16% reduction in death in men (HR: 0.84 [95% CI: 0.82 to 0.85]). In multivariable analyses controlling for comorbidities, LBBB was associated with a 26% reduction in death in women (HR: 0.74 [95% CI: 0.71 to 0.77]) and a 15% reduction in death in men (HR: 0.85 [95% CI: 0.83 to 0.87]). A significant interaction (p < 0.0001) between sex and LBBB was seen.LBBB diagnosis is associated with greater survival in women than in men receiving CRT-D, and this discrepancy is not explained by differences in measured comorbidities. Possible explanations for this difference include that LBBB may have different prognostic significance according to sex or that LBBB diagnosis is more often false-positive in men compared with women.
- A Novel ECG-Index for Prediction of Ventricular Arrhythmias in Patients after Myocardial Infarction. [JOURNAL ARTICLE]
- Ann Noninvasive Electrocardiol 2014 Mar 10.
Risk prediction of ventricular arrhythmias after myocardial infarction (MI) is still insufficient. Prolonged QTc is a known risk marker of mortality and ventricular arrhythmias. QTc has not achieved clinical importance in predicting arrhythmic events in patients after MI. Recent studies have displayed that the terminal part of the QT-interval, Tpeak to Tend (TpTe), may be a more promising predictor of adverse outcome. Herein, we assessed whether TpTe may serve as a predictor of ventricular arrhythmias in patients with previous MI fulfilling current implantable cardioverter-defibrillator (ICD) indications.Seventy-six patients with previous MI eligible for ICD therapy were prospectively enrolled. ECG measurements at baseline were recorded using a 12-lead ECG with 50 mm/s paper speed. TpTe was measured from peak of the T wave to end of T wave. Events during follow up were defined as ventricular arrhythmias requiring appropriate ICD therapy, including antitachycardia pacing and shock.During 23 ± 19 months, arrhythmic events occurred in 36 (47%) patients. TpTe was longer in ICD patients with recorded ventricular arrhythmias compared with those without (116 ± 26 ms vs. 102 ± 20 ms; P = 0.01), whereas ejection fraction (EF) at baseline did not differ (35 ± 9% vs. 35 ± 11%; P = 0.87). TpTe was an independent predictor of ventricular arrhythmias when adjusted for age, EF and QRS duration (HR 1.16; 95% CI 1.03-1.31; P = 0.02).TpTe predicted malignant arrhythmias in patients after MI independently of EF. TpTe may contribute in the risk stratification of patients to identify post-MI patients disposed to malignant arrhythmias and their need of ICD therapy.
- HCN channelopathy and cardiac electrophysiologic dysfunction in genetic and acquired rat epilepsy models. [JOURNAL ARTICLE]
- Epilepsia 2014 Mar 4.
Evidence from animal and human studies indicates that epilepsy can affect cardiac function, although the molecular basis of this remains poorly understood. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels generate pacemaker activity and modulate cellular excitability in the brain and heart, with altered expression and function associated with epilepsy and cardiomyopathies. Whether HCN expression is altered in the heart in association with epilepsy has not been investigated previously. We studied cardiac electrophysiologic properties and HCN channel subunit expression in rat models of genetic generalized epilepsy (Genetic Absence Epilepsy Rats from Strasbourg, GAERS) and acquired temporal lobe epilepsy (post-status epilepticus SE). We hypothesized that the development of epilepsy is associated with altered cardiac electrophysiologic function and altered cardiac HCN channel expression.Electrocardiography studies were recorded in vivo in rats and in vitro in isolated hearts. Cardiac HCN channel messenger RNA (mRNA) and protein expression were measured using quantitative PCR and Western blotting respectively.Cardiac electrophysiology was significantly altered in adult GAERS, with slower heart rate, shorter QRS duration, longer QTc interval, and greater standard deviation of RR intervals compared to control rats. In the post-SE model, we observed similar interictal changes in several of these parameters, and we also observed consistent and striking bradycardia associated with the onset of ictal activity. Molecular analysis demonstrated significant reductions in cardiac HCN2 mRNA and protein expression in both models, providing a molecular correlate of these electrophysiologic abnormalities.These results demonstrate that ion channelopathies and cardiac dysfunction can develop as a secondary consequence of chronic epilepsy, which may have relevance for the pathophysiology of cardiac dysfunction in patients with epilepsy.
- Effectiveness of implantable cardioverter defibrillators for primary prevention of sudden cardiac death in subgroups a systematic review. [Journal Article, Meta-Analysis, Research Support, U.S. Gov't, P.H.S., Review]
- Ann Intern Med 2014 Jan 21; 160(2):111-21.
Previous systematic reviews of implantable cardioverter defibrillators (ICDs) used for primary prevention of sudden cardiac death (SCD) concluded that ICDs are less effective in women and the elderly.To examine ICD effectiveness for primary prevention of SCD across subgroups by sex, age, New York Heart Association class, left ventricular ejection fraction, heart failure, left bundle branch block, QRS interval, time since myocardial infarction, blood urea nitrogen level, and diabetes.MEDLINE and the Cochrane Central Register of Controlled Trials through 3 September 2013 with no language restriction.Researchers screened articles for studies comparing ICD versus no ICD for primary prevention. Data Extraction: Data were extracted about study design, patients, interventions, mortality and SCD outcomes, subgroup characteristics, and subgroup effects. Quality of subgroup analyses was determined by consensus. Relative odds ratios comparing subgroup effects were calculated, and random-effects model meta-analyses were conducted on these ratios.Meta-analysis of 14 studies showed a decrease in deaths and SCDs due to ICD treatment. Ten studies provided subgroup analyses. Nine studies compared ICD versus no ICD, whereas one compared cardiac resynchronization therapy plus a defibrillator versus no ICD. Within-study interaction tests and across-study meta-analyses yielded weak evidence that did not show differences for all-cause mortality in subgroups by sex, age, and QRS interval. The evidence was indeterminate for other evaluated subgroups because of a paucity of data.Many subgroup analyses were underpowered, which may have resulted in false-negative findings.Weak evidence fails to show differences for all-cause mortality in subgroups of sex, age, and QRS interval. Evidence is indeterminate for all-cause mortality in the other subgroups and for SCD.Agency for Healthcare Research and Quality.