Long-term implications of cumulative right ventricular pacing among patients with an implantable cardioverter-defibrillator.

Background: Limited data regarding the effect of right ventricular pacing (RVP) on long-term survival following implantable cardioverter-defibrillator (ICD) implantation are available.

Objective: The purpose of this study was to evaluate the effect of RVP on the long-term survival benefit of primary ICD therapy.

Methods: Mortality data were obtained for all patients enrolled in the Multicenter Automatic Defibrillator Trial-II (MADIT-II) during an extended follow-up period of 8 years.

Trigger-specific risk factors and response to therapy in long QT syndrome type 2.

Background: Cardiac events in patients with long QT syndrome type 2 (LQT2) are predominately associated with sudden arousal. However, exercise-induced events also occur in this population.

Objective: The purpose of this study was to test the hypothesis that risk factors show a trigger-specific association with cardiac events in LQT2 patients.

Long-term benefit of primary prevention with an implantable cardioverter-defibrillator: an extended 8-year follow-up study of the Multicenter Automatic Defibrillator Implantation Trial II.

Background: The Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) showed a significant 31 reduction in the risk of death with primary implantable cardioverter-defibrillator (ICD) therapy during a median follow-up of 1.5 years. However, currently there are no data on the long-term efficacy of primary defibrillator therapy.

Relation between renal function and response to cardiac resynchronization therapy in Multicenter Automatic Defibrillator Implantation Trial--Cardiac Resynchronization Therapy (MADIT-CRT).

Background: Cardiorenal interactions have been shown to affect outcome in heart failure patients but were not related to response to cardiac resynchronization therapy (CRT).

Objective: The purpose of this study was to test our hypothesis that assessment of markers of prerenal failure may help identify mildly symptomatic HF patients with diminished effective circulating blood volume who will benefit from CRT.

Methods: The benefit of CRT with a defibrillator (CRT-D) as compared with defibrillator-only therapy in reducing the risk of HF or death was assessed by renal function parameters (including serum creatinine [SCr], blood urea nitrogen [BUN], and the ratio of BUN to SCr [BUN:SCr], dichotomized at median values and into approximate quartiles) among 1,803 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy.

LQTS gene LOVD database.

The Long QT Syndrome (LQTS) is a group of genetically heterogeneous disorders that predisposes young individuals to ventricular arrhythmias and sudden death. LQTS is mainly caused by mutations in genes encoding subunits of cardiac ion channels (KCNQ1, KCNH2,SCN5A, KCNE1, and KCNE2). Many other genes involved in LQTS have been described recently(KCNJ2, AKAP9, ANK2, CACNA1C, SCNA4B, SNTA1, and CAV3).

Effect of cardiac resynchronization therapy on reverse remodeling and relation to outcome: multicenter automatic defibrillator implantation trial: cardiac resynchronization therapy.

Background: Cardiac resynchronization therapy (CRT) plus implantation of an implantable cardioverter defibrillator (ICD) reduced the risk of death or heart failure event in patients with mildly symptomatic heart failure, left ventricular dysfunction, and wide QRS complex compared with an ICD only. We assessed echocardiographic changes in patients enrolled in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation Trial: Cardiac Resynchronization Therapy) to evaluate whether the improvement in outcomes with CRT plus an ICD was associated with favorable alterations in cardiac size and function.

Methods And Results: A total of 1,820 patients were randomly assigned to CRT plus an ICD or to an ICD only in a 3:2 ratio.

Ion channel mechanisms related to sudden cardiac death in phenotype-negative long-QT syndrome genotype-phenotype correlations of the KCNQ1(S349W) mutation.

Unlabelled:  

Background: Data regarding possible ion channel mechanisms that predispose to ventricular tachyarrhythmias in patients with phenotype-negative long-QT syndrome (LQTS) are limited.

Methods And Results: We carried out cellular expression studies for the S349W mutation in the KCNQ1 channel, which was identified in 15 patients from the International LQTS Registry who experienced a high rate of cardiac events despite lack of significant QTc prolongation. The clinical outcome of S349W mutation carriers was compared with that of QTc-matched carriers of haploinsufficient missense (n = 30) and nonsense (n = 45) KCNQ1 mutations.

Time dependence of life-threatening ventricular tachyarrhythmias after coronary revascularization in MADIT-CRT.

Background: Coronary revascularization (CR) may confer electrical stability in patients with ischemic cardiomyopathy. However, data regarding the effect of CR on the development of ventricular tachyarrhythmias in this population are limited.

Objective: The purpose of this study was to evaluate the association between CR and arrhythmic risk in postmyocardial infarction (post-MI) patients with left ventricular dysfunction.

Cholesteryl ester transfer protein polymorphism (TaqIB) associates with risk in postinfarction patients with high C-reactive protein and high-density lipoprotein cholesterol levels.

Objective: To investigate the roles of inflammation and a cholesteryl ester transfer protein (CETP) polymorphism potentially related to recent findings demonstrating coronary risk with increasing high-density lipoprotein cholesterol (HDL-C) level.

Methods And Results: A novel graphical exploratory data analysis tool allowed the examination of coronary risk in postinfarction patients relating to HDL-C and C-reactive protein levels. Results demonstrated a high-risk subgroup, defined by high HDL-C and C-reactive protein levels, exhibiting larger HDL particles and lower lipoprotein-associated phospholipaseA(2) levels than lower-risk patients.

What we have learned from the family of multicenter automatic defibrillator implantation trials.

Electrical device therapy began 50 years ago with the external defibrillator, and was followed subsequently with the introduction of implantable cardiac pacemakers, defibrillators, and resynchronization devices to prevent bradycardia, sudden arrhythmic death, and heart failure. During the past 20 years the Multicenter Automatic Defibrillator Implantation Trial (MADIT) research group has carried out a series of trials, including the MADIT-I, MADIT-II, and MADIT-III (MADIT-CRT), that have focused on improving the outcomes for patients with ischemic and nonischemic cardiac disease. The most recent MADIT-CRT trial showed that a cardiac resynchronization therapy device with defibrillator (CRT-D) was effective in reducing the risk of heart failure or death, whichever came first, in cardiac patients who were asymptomatic or minimally symptomatic (New York Heart Association class I or II) with reduced ejection fraction < or =0.

Risk factors for recurrent heart failure events in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II).

Unlabelled: Risk Factors for Recurrent Heart Failure.

Background: This study was designed to identify risk factors for recurrent heart failure (HF) events in patients with ischemic left ventricular dysfunction enrolled in the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II).

Methods And Results: The Prentice, Williams, and Peterson (PWP) statistical model was utilized to identify and compare risk factors for 1 or ≥ 2 HF hospitalizations among 1,218 patients with ischemic left ventricular dysfunction enrolled in the MADIT-II trial.

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.

Relation of body mass index to sudden cardiac death and the benefit of implantable cardioverter-defibrillator in patients with left ventricular dysfunction after healing of myocardial infarction.

Obesity has been identified as a risk factor for cardiovascular disease and heart failure. However, data regarding the relation of body mass index (BMI) to outcome in patients with established heart failure are conflicting. We examined the risk of all-cause mortality and sudden cardiac death (SCD) in 1,231 patients after myocardial infarction with left ventricular dysfunction enrolled the Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II).

Risk of fatal arrhythmic events in long QT syndrome patients after syncope.

Objectives: The aim of this study was to identify risk factors for fatal arrhythmias in long QT syndrome (LQTS) patients presenting with syncope.

Background: Syncope is highly predictive for future fatal arrhythmias in the LQTS. However, there are no data regarding risk stratification and management strategies in the high-risk subset of LQTS patients presenting with syncope.

Long QT syndrome in African-Americans.

Background: We evaluated the risk factors and clinical course of Long QT syndrome (LQTS) in African-American patients.

Methods: The study involved 41 African-Americans and 3456 Caucasians with a QTc > or = 450 ms from the U.S.

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).

Mutation-specific risk in two genetic forms of type 3 long QT syndrome.

The clinical course of patients with 2 relatively common long QT syndrome type 3 mutations has not been well described. In the present study, we investigated the mutational-specific risk in patients with deletional (DeltaKPQ) and missense (D1790G) mutations involving the SCN5A gene. The study population involved 50 patients with the DeltaKPQ mutation and 35 patients with the D1790G mutation.

Time-dependent risk of Fidelis lead failure.

The Medtronic Sprint Fidelis leads (models 6930, 6931, 6948, 6949) are 6.6-F bipolar high-voltage implantable cardioverter-defibrillator electrodes that were first introduced in September 2004. In October 2007, Fidelis leads were removed from the market.

Influence of diabetes mellitus on outcome in patients over 40 years of age with the long QT syndrome.

Diabetes mellitus can affect ventricular repolarization, and we investigated the impact of diabetes on the risk for cardiac events in older patients with long QT syndrome (LQTS). The study population consisted of 1,152 patients with QTc interval >/=450 ms who were enrolled in the United States portion of the International Long QT Syndrome Registry and survived >40 years of age. Patients were categorized as having diabetes if they received oral diabetic medication or insulin.