JT interval: What does this interval mean?

The JTp interval gained interest as a marker differentiating effects of drugs on cardiac ion channels. For JTp interval, both the beginning - identification of J point and identification of T wave end remains the subject of substantial variability. We aimed to analyze diagnostic and prognostic performance of JTp interval in the International LQTS Registry data.

Early procedure-related adverse events by gender in MADIT-CRT.

Background: Whether gender differences exist in procedure-related adverse events following cardiac resynchronization therapy (CRT-D) implantation is unknown. We investigated the type and frequency of procedure-related adverse events among those enrolled in MADIT-CRT and identified clinical predictors for gender-specific events.

Methods: We compared differences in the rate of procedure-related adverse events by gender (444 females and 1,346 males) that occurred ≤30 days after the index procedure in the implantable cardioverter defibrillator (ICD) and CRT-D groups.

A metric for evaluating the cardiac response to resynchronization therapy.

We hypothesized that the response to cardiac resynchronization therapy with a defibrillator (CRT-D) in patients with mildly symptomatic heart failure (HF) is more favorable than the commonly referenced figure of 70%. This study involves the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) study population in which paired echocardiograms from baseline and 1-year follow-up were available in 621 implantable cardioverter-defibrillator-treated patients and 749 patients treated with CRT-D. We prespecified CRT-D responders as the patients who at 1-year follow-up had a reduction in left ventricular end-systolic volume (LVESV) that corresponded to the top (best) quintile of LVESV reduction in the implantable cardioverter-defibrillator-treated patients, that is, a ≥17% reduction in LVESV.

The effect of weight loss on clinical outcomes in patients implanted with a cardiac resynchronization therapy device-A MADIT-CRT substudy.

Background: There are no data regarding the effect of weight loss on clinical outcomes in patients undergoing cardiac resynchronization therapy. This study was designed to evaluate the effect of weight loss on clinical outcomes in patients implanted with a cardiac resynchronization therapy with defibrillator (CRT-D).

Methods And Results: The risk of heart failure (HF) or death, and of death alone, was compared between patients with and without weight loss of ≥2 kg or more at 1 year in the CRT-D arm of the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT).

Prognostic value of average T-wave alternans and QT variability for cardiac events in MADIT-II patients.

Background: Identifying which patients might benefit the most from ICD therapy remains challenging. We hypothesize that increased T-wave alternans (TWA) and QT variability (QTV) provide complementary information for predicting appropriate ICD therapy in patients with previous myocardial infarction and reduced ejection fraction.

Methods: We analyzed 10-min resting ECGs from MADIT-II patients with baseline heart rate >80 beats/min.

Response of right ventricular size to treatment with cardiac resynchronization therapy and the risk of ventricular tachyarrhythmias in MADIT-CRT.

Background: Cardiac resynchronization therapy (CRT) is increasingly recognized for its ability to reduce ventricular tachyarrhythmias, possibly associated with left ventricular reverse remodeling, but the role of the right ventricle (RV) in this process has not been examined.

Objective: The purpose of this study was to investigate the relationship between ventricular tachyarrhythmias and change in RV dimensions in patients receiving CRT with a defibrillator (CRT-D).

Methods: Multivariate Cox proportional hazards regression modeling was used to assess the risk for fast (≥180 bpm) ventricular tachycardia/ventricular fibrillation (VT/VF) or death by baseline and follow-up RV size (defined as right ventricular end-diastolic area [RVEDA]) among 1495 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT).

Effectiveness of cardiac resynchronization therapy with defibrillator in at-risk black and white cardiac patients.

Background: There are limited data regarding racial differences in response to cardiac resynchronization therapy with defibrillator (CRT-D).

Methods: We assessed the effectiveness of CRT-D, as compared to implantable cardioverter defibrillator (ICD) therapy alone, in reducing the risk of heart failure (HF) or death and changes in cardiac volumes among 1638 (90%) white patients and 143 (8%) black patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT).

Results: Enrolled black patients displayed a higher frequency of diabetes mellitus, treated hypertension, higher creatinine levels, and a lower distance walked in the baseline 6-minute walk test.

The influence of left ventricular ejection fraction on the effectiveness of cardiac resynchronization therapy: MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy).

Objectives: The aim of this study was to evaluate the relationship between left ventricular (LV) ejection fraction and clinical outcome to cardiac resynchronization therapy (CRT) in mild heart failure patients enrolled in MADIT-CRT [corrected].

Background: Left ventricular ejection fraction (LVEF) is a surrogate marker of heart failure (HF) status and associated risk. Data on the effectiveness of cardiac resynchronization therapy with defibrillator (CRT-D) in patients with mild HF and better LVEF are limited.

Left ventricular lead location and the risk of ventricular arrhythmias in the MADIT-CRT trial.

Aims: We aimed to evaluate the influence of left ventricular (LV) lead position on the risk of ventricular tachyarrhythmias in cardiac resynchronization therapy (CRT) patients.

Methods And Results: Left ventricular (LV) lead position was evaluated by biplane coronary venograms and anterior/posterior, lateral chest X-rays in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy (MADIT-CRT). The LV lead location could be defined in 797 of 1089 patients (73%).

Combined assessment of sex- and mutation-specific information for risk stratification in type 1 long QT syndrome.

Background: Men and women with type 1 long QT syndrome (LQT1) exhibit time-dependent differences in the risk for cardiac events.

Objective: We hypothesized that sex-specific risk for LQT1 is related to the location and function of the disease-causing mutation in the KCNQ1 gene.

Methods: The risk for life-threatening cardiac events (comprising aborted cardiac arrest [ACA] or sudden cardiac death [SCD]) from birth through age 40 years was assessed among 1051 individuals with LQT1 (450 men and 601 women) by the location and function of the LQT1-causing mutation (prespecified as mutations in the intracellular domains linking the membrane-spanning segments [ie, S2-S3 and S4-S5 cytoplasmic loops] involved in adrenergic channel regulation vs other mutations).

Risk of syncope in family members who are genotype-negative for a family-associated long-QT syndrome mutation.

Background: Current clinical diagnosis of long-QT syndrome (LQTS) includes genetic testing of family members of mutation-positive patients. The present study was designed to assess the clinical course of individuals who are found negative for the LQTS-causing mutation in their families.

Methods And Results: Multivariate Cox proportional hazards model was used to assess the risk for cardiac events (comprising syncope, aborted cardiac arrest [ACA], or sudden cardiac death [SCD]) from birth through age 40 years among 1828 subjects from the LQTS Registry who were found negative for their family LQTS-causing mutation.

Reduction of the risk of recurring heart failure events with cardiac resynchronization therapy: MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy).

Objectives: The evaluation of the risk of recurring heart failure events (HFEs) was a pre-specified substudy of MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy).

Background: There are limited data regarding the effect of cardiac resynchronization therapy with a defibrillator (CRT-D) on the occurrence of recurring heart failure episodes after a first post-implantation HFE.

Methods: Data with regard to recurring HFEs were prospectively collected for all 1,820 MADIT-CRT participants.

Mutation and gender-specific risk in type 2 long QT syndrome: implications for risk stratification for life-threatening cardiac events in patients with long QT syndrome.

Background: Men and women with type 2 long QT syndrome (LQT2) exhibit time-dependent differences in the risk for cardiac events. We hypothesized that data regarding the location of the disease-causing mutation in the KCNH2 channel may affect gender-specific risk in LQT2.

Objective: This study sought to risk-stratify LQT2 patients for life-threatening cardiac events based on clinical and genetic information.

Genotype-specific QT correction for heart rate and the risk of life-threatening cardiac events in adolescents with congenital long-QT syndrome.

Background: A prolonged QT interval corrected for heart rate (QTc) is a major risk factor in patients with long QT syndrome (LQTS). However, heart rate-related risk in this genetic disorder differs among genotypes.

Objective: This study hypothesized that risk assessment in LQTS patients should incorporate genotype-specific QT correction for heart rate.

T-wave morphology abnormalities in benign, potent, and arrhythmogenic I(kr) inhibition.

Background: There is a consensus on the limited value of the QTc interval prolongation as a surrogate marker of drug cardiotoxicity and as a risk stratifier in inherited long QT syndrome (LQTS) patients.

Objective: We investigated the interest of repolarization morphology in the acquired and the inherited LQTS.

Methods: We analyzed 2 retrospective electrocardiographic (ECG) datasets from healthy on/off moxifloxacin and from genotyped KCNH2 patients.

Value of the signal-averaged electrocardiogram in arrhythmogenic right ventricular cardiomyopathy/dysplasia.

Background: Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited disease that causes structural and functional abnormalities of the right ventricle (RV). The presence of late potentials as assessed by the signal-averaged electrocardiogram (SAECG) is a minor task force criterion.

Objective: The purpose of this study was to examine the diagnostic and clinical value of the SAECG in a large population of genotyped ARVC/D probands.

Beta-blocker efficacy in high-risk patients with the congenital long-QT syndrome types 1 and 2: implications for patient management.

Background: Beta-blockers are the mainstay therapy in patients with the congenital long-QT syndrome (LQTS) types 1 and 2. However, limited data exist regarding the efficacy and limitations of this form of medical management within high-risk subsets of these populations.

Methods And Results: Multivariate analysis was carried out to identify age-related gender- and genotype-specific risk factors for cardiac events (comprising syncope, aborted cardiac arrest [ACA] or sudden cardiac death [SCD]) from birth through age 40 years among 971 LQT1 (n = 549) and LQT2 (n = 422) patients from the International LQTS Registry.

Abnormal P-wave morphology is a predictor of atrial fibrillation development and cardiac death in MADIT II patients.

Background: Several ECG-based approaches have been shown to add value when risk-stratifying patients with congestive heart failure, but little attention has been paid to the prognostic value of abnormal atrial depolarization in this context. The aim of this study was to noninvasively analyze the atrial depolarization phase to identify markers associated with increased risk of mortality, deterioration of heart failure, and development of atrial fibrillation (AF) in a high-risk population with advanced congestive heart failure and a history of acute myocardial infarction.

Methods: Patients included in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) with sinus rhythm at baseline were studied (n = 802).

Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study.

Background: Prior reports on patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) focused on individuals with advanced forms of the disease. Data on the diagnostic performance of various testing modalities in newly identified individuals suspected of having ARVC/D are limited.

Objective: The purpose of the Multidisciplinary Study of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia was to study the clinical characteristics and diagnostic evaluation of a large group of patients newly identified with ARVC/D.

Predictors of long-term mortality in Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) patients with implantable cardioverter-defibrillators.

Background: Data on long-term follow-up and factors influencing mortality in implantable cardioverter-defibrillator (ICD) recipients are limited.

Objective: The aim of this study was to evaluate mortality during long-term follow-up and the predictive value of several risk markers in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) patients with implanted cardioverter-defibrillators (ICDs).

Methods: The study involved U.

Baseline values and sotalol-induced changes of ventricular repolarization duration, heterogeneity, and instability in patients with a history of drug-induced torsades de pointes.

The authors investigated whether computerized parameters quantifying ventricular repolarization delay, heterogeneity, and instability characterize individuals who developed drug-induced Torsades de Pointes. Assessing an individual's propensity to Torsades de Pointes when exposed to a QT-prolonging drug is challenging because baseline QT prolongation has limited predictive value. Five-minute digital 12-lead electrocardiograms were acquired at baseline and after a sotalol challenge in 16 patients who had a history of Torsades de Pointes in the context of a QT-prolonging drug and 17 patients who did not have such history.

Long-QT syndrome after age 40.

Background: Previous studies that assessed the risk of life-threatening cardiac events in patients with congenital long-QT syndrome (LQTS) have focused mainly on the first 4 decades of life, whereas the clinical course of this inherited cardiac disorder in the older population has not been studied.

Methods And Results: The risk of aborted cardiac arrest or death from age 41 though 75 years was assessed in 2759 subjects from the International LQTS Registry, categorized into electrocardiographically affected (corrected QT interval [QTc] > or = 470 ms), borderline (QTc 440 to 469 ms), and unaffected (QTc < 440 ms) subgroups. The affected versus unaffected adjusted hazard ratio for aborted cardiac arrest or death was 2.

Improving the detection of subtle I(Kr)-inhibition: assessing electrocardiographic abnormalities of repolarization induced by moxifloxacin.

Background: QT prolongation is an incomplete measure of drug-induced changes in repolarization. In this study, we investigated a novel, automatic ECG technique for describing ventricular repolarization morphology and we compared these results to corrected QT (QTc) prolongation for identifying ECGs of healthy individuals on moxifloxacin.

Methods: We analysed data from the US FDA ECG Warehouse involving 160 standard ECGs from 40 healthy subjects enrolled in a randomized, parallel, placebo-controlled, 'thorough QT' study.