Continuous ECG monitoring versus mobile telemetry: A comparison of arrhythmia diagnostics in human- versus algorithmic-dependent systems.

Background: Clinicians rarely scrutinize the full disclosure of a myriad of FDA-approved long-term rhythm monitors, and they rely on manufacturers to detect and report relevant rhythm abnormalities.

Objective: The objective of this study is to compare the diagnostic accuracy between mobile cardiac telemetry (MCT), which uses an algorithm-based detection strategy, and continuous long-term electrocardiography (LT-ECG) monitoring, which uses a human-based detection strategy.

Methods: In an outpatient arrhythmia clinic, we enrolled 50 sequential patients ordered to wear a 30-day MCT, to simultaneously wear a continuous LT-ECG monitor.

Outcomes for patients with anterior myocardial infarction and prior cardiac arrest in the home automated external defibrillator trial (HAT).

Background: Patients with sudden cardiac arrest occurring in the acute phase of myocardial infarction (MI-SCA) are believed to be at similar risk of death after revascularization compared with MI patients without SCA (MI-no SCA). Among patients with anterior MI, we examined whether those with MI-SCA were at greater risk of all-cause mortality or sudden cardiac death (SCD) than MI-no SCA patients.

Methods: The Home Automated External Defibrillator Trial enrolled patients with anterior MI who had not received or were candidates for an implantable cardioverter defibrillator (ICD).

Ventricular Fibrillation Recurrences in Successfully Shocked Out-of-Hospital Cardiac Arrests.

The prognostic impact of ventricular fibrillation (VF) recurrences after a successful shock in out-of-hospital cardiac arrest (OOHCA) is still poorly understood, and some evidence suggests a potential pro-arrhythmic effect of chest compressions in this setting. In the present analysis, we looked at the short-term and long-term prognosis of VF recurrences in OOHCA. And their potential association with chest compressions.

Long-Term Outcomes of Implantable Cardioverter-Defibrillator Therapy in the SCD-HeFT.

Background: The SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) randomized 2,521 patients with moderate heart failure (HF) to amiodarone, placebo drug, or implantable cardioverter-defibrillator (ICD) therapy. Original trial follow-up ended October 31, 2003. Over a median 45.

Development and validation of warning system of ventricular tachyarrhythmia in patients with heart failure with heart rate variability data.

Implantable-cardioverter defibrillators (ICD) detect and terminate life-threatening ventricular tachyarrhythmia with electric shocks after they occur. This puts patients at risk if they are driving or in a situation where they can fall. ICD's shocks are also very painful and affect a patient's quality of life.

Improving the Use of Primary Prevention Implantable Cardioverter-Defibrillators Therapy With Validated Patient-Centric Risk Estimates.

Objectives: The authors previously developed the Seattle Proportional Risk Model (SPRM) in systolic heart failure patients without implantable cardioverter-defibrillators (ICDs)to predict the proportion of deaths that were sudden. They subsequently validated the SPRM in 2 observational ICD data sets. The objectives in the present study were to determine whether this validated model could improve identification of clinically important variations in the expected magnitude of ICD survival benefit by using a pivotal randomized trial of primary prevention ICD therapy.

Implantable cardioverter-defibrillators in heart failure patients with reduced ejection fraction and diabetes.

Aim: There is limited information on the outcomes after primary prevention implantable cardioverter-defibrillator (ICD) implantation in patients with heart failure (HF) and diabetes. This analysis evaluates the effectiveness of a strategy of ICD plus medical therapy vs. medical therapy alone among patients with HF and diabetes.

New York Heart Association class and the survival benefit from primary prevention implantable cardioverter defibrillators: A pooled analysis of 4 randomized controlled trials.

Background: Primary prevention implantable cardioverter defibrillator (ICD) reduce all-cause mortality by reducing sudden cardiac death. There are conflicting data regarding whether patients with more advanced heart failure derive ICD benefit owing to the competing risk of nonsudden death.

Methods: We performed a patient-level meta-analysis of New York Heart Association (NYHA) class II/III heart failure patients (left ventricular ejection fraction ≤35%) from 4 primary prevention ICD trials (MADIT-I, MADIT-II, DEFINITE, SCD-HeFT).

Predicting appropriate shocks in patients with heart failure: Patient level meta-analysis from SCD-HeFT and MADIT II.

Background: No precise tools exist to predict appropriate shocks in patients with a primary prevention ICD. We sought to identify characteristics predictive of appropriate shocks in patients with a primary prevention implantable cardioverter defibrillator (ICD).

Methods: Using patient-level data from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), we identified patients with any appropriate shock.

Recent developments in the subcutaneous ICD.

The subcutaneous implantable cardioverter-defibrillator (ICD) was developed as a simple device to reduce the morbidity of ICD therapy while providing a comparable reduction in sudden death from ventricular fibrillation. This review highlights the differences compared to the traditional ICD. It includes recent data on safety and efficacy, as well as best practices on screening and programming, and discusses expected future developments.

Community-based automated external defibrillator only resuscitation for out-of-hospital cardiac arrest patients.

Background: Speed is the cornerstone of rescue for out-of-hospital cardiac arrest. As a consequence, community participation programs have been initiated to decrease response times. Even in the very best of these programs, however, short-term survival rates hover around 10% and long-term survival rates are half that.

SCD-HeFT: Use of R-R interval statistics for long-term risk stratification for arrhythmic sudden cardiac death.

Background: In the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), a significant fraction of the patients with congestive heart failure ultimately did not die suddenly of arrhythmic causes. Patients with CHF will benefit from better tools to identify if implantable cardioverter-defibrillator (ICD) therapy is needed.

Objectives: We aimed to identify predictor variables from baseline SCD-HeFT patients' R-R intervals that correlate to arrhythmic sudden cardiac death (SCD) and mortality and to design an ICD therapy screening test.

Outcomes of implantable cardioverter-defibrillator use in patients with comorbidities: results from a combined analysis of 4 randomized clinical trials.

Objectives: The aim of this study was to determine if the benefit of implantable cardioverter-defibrillators (ICDs) is modulated by medical comorbidity.

Background: Primary prevention ICDs improve survival in patients at risk for sudden cardiac death. Their benefit in patients with significant comorbid illness has not been demonstrated.

Unexpected deviation in circadian variation of ventricular arrhythmias: the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial).

Objectives: This study sought to determine whether circadian patterns in ventricular arrhythmias (VAs) occur in a current primary prevention defibrillator (implantable cardioverter-defibrillator [ICD]) population.

Background: Cardiovascular events, including VAs, demonstrate biorhythmic periodicity.

Methods: We tested for deviation from the previously described occurrences of a morning peak, early morning nadir, and peak on Mondays in ICD therapies using generalized estimating equations and Student t tests.

Use of the 6-min walk distance to identify variations in treatment benefits from implantable cardioverter-defibrillator and amiodarone: results from the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial).

Objectives: The purpose of this study was to determine if 6-min walk test data assists in treatment decisions for patients with heart failure.

Background: In the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial), a pre-specified subgroup analysis showed that patients with New York Heart Association functional class III symptoms did not benefit from implantable cardioverter-defibrillator (ICD) therapy and appeared to be harmed by amiodarone, whereas New York Heart Association functional class II patients obtained significant survival benefit from ICD. We postulated that a more objective measure of functional capacity, such as 6-min walk (6MW) distance, might provide a better tool for selecting these preventive therapies.

Thyroid function in heart failure and impact on mortality.

Objectives: The aim of this study was to investigate whether patients with systolic heart failure (HF) and abnormal thyroid function are at increased risk for death.

Background: Thyroid hormone homeostasis is vital to the optimal functioning of the cardiovascular system, but an independent prognostic effect of thyroid abnormalities in patients with HF has not been established.

Methods: In SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial), which randomized patients with ischemic or nonischemic HF to placebo or amiodarone or implantable cardioverter-defibrillator therapy, thyroid-stimulating hormone (TSH) was measured at baseline and at 6-month intervals throughout the 5-year study.

No benefit of a dual coil over a single coil ICD lead: evidence from the Sudden Cardiac Death in Heart Failure Trial.

Background: Dual coil implantable cardioverter-defibrillator (ICD) leads with a superior vena cava (SVC) electrode have been considered standard of care despite sparse data suggesting improved ICD defibrillation efficacy. SVC coils increase lead complexity, cost, risk of lead failure, and lead removal.

Objective: To compare all-cause mortality, sudden cardiac death, implant defibrillation threshold (DFT) test energies, appropriate shock rates, and first shock efficacy for ventricular tachyarrhythmias for dual coil vs single coil leads in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).

Rapid-rate nonsustained ventricular tachycardia found on implantable cardioverter-defibrillator interrogation: relationship to outcomes in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial).

Objectives: The aim of this study was to examine rapid-rate nonsustained ventricular tachycardia (RR-NSVT) during routine implantable cardioverter-defibrillator (ICD) evaluation in patients with heart failure and its relationship to outcomes.

Background: The clinical implications of RR-NSVT identified during routine ICD interrogation are unclear. In this study, the occurrence of RR-NSVT and its association with ICD shocks and mortality in SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) were examined.