Implant and Midterm Outcomes of the Subcutaneous Implantable Cardioverter-Defibrillator Registry: The EFFORTLESS Study.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to defibrillate ventricular arrhythmias, avoiding drawbacks of transvenous leads. The global EFFORTLESS S-ICD (Evaluation oF FactORs ImpacTing CLinical Outcome and Cost EffectiveneSS of the S-ICD) registry is collecting outcomes in 985 patients during a 5-year follow-up.

Objectives: The primary goal of the EFFORTLESS registry is to determine the safety of the S-ICD by evaluating complications and inappropriate shock rate.

Impact of an Age-Adjusted Co-morbidity Index on Survival of Patients With Heart Failure Implanted With Cardiac Resynchronization Therapy Devices.

Age is an adverse prognostic factor in patients with heart failure. We aimed to assess the impact of age and noncardiac co-morbidities in the outcome of patients undergoing cardiac resynchronization therapy (CRT), and determine which of these two factors is the most important predictor of survival. The study involved a single-center retrospective assessment of 697 consecutive CRT implants during a 12-year period.

D242N, a K7.1 LQTS mutation uncovers a key residue for I voltage dependence.

K7.1 and KCNE1 co-assemble to give rise to the I current, one of the most important repolarizing currents of the cardiac action potential. Its relevance is underscored by the identification of >500 mutations in K7.

Electrical and Structural Substrate of Arrhythmogenic Right Ventricular Cardiomyopathy Determined Using Noninvasive Electrocardiographic Imaging and Late Gadolinium Magnetic Resonance Imaging.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a significant cause of sudden cardiac death in the young. Improved noninvasive assessment of ARVC and better understanding of the disease substrate are important for improving patient outcomes.

Methods And Results: We studied 20 genotyped ARVC patients with a broad spectrum of disease using electrocardiographic imaging (a method for noninvasive cardiac electrophysiology mapping) and advanced late gadolinium enhancement cardiac magnetic resonance scar imaging.

Catheter ablation for ventricular tachycardia in patients with cardiac sarcoidosis: a systematic review.

Aims: Cardiac sarcoidosis (CS) is associated with a poor prognosis. Important features of CS include heart failure, conduction abnormalities, and ventricular arrhythmias. Ventricular tachycardia (VT) is often refractory to antiarrhythmic drugs (AAD) and immunosuppression.

Electrocardiographic differentiation of idiopathic right ventricular outflow tract ectopy from early arrhythmogenic right ventricular cardiomyopathy.

Aims: The differentiation between idiopathic right ventricular outflow tract (RVOT) arrhythmias and early arrhythmogenic right ventricular cardiomyopathy (ARVC) can be challenging. We aimed to assess whether QRS morphological features and coupling interval of ventricular ectopic beats (VEBs) can improve differentiation between the two conditions.

Methods And Results: Twenty desmosomal-gene mutation carriers (13 females, mean age 43 years) with no or mild ARVC phenotypic expression and 33 age- and sex-matched subjects with idiopathic RVOT arrhythmias were studied.

Disease Severity and Exercise Testing Reduce Subcutaneous Implantable Cardioverter-Defibrillator Left Sternal ECG Screening Success in Hypertrophic Cardiomyopathy.

Background: The features of the hypertrophic cardiomyopathy (HCM) ECG make it a challenge for subcutaneous implantable cardioverter-defibrillator (S-ICD) screening. We aimed to investigate the causes of screening failure at rest and on exercise to inform optimal S-ICD ECG vector development.

Methods And Results: One hundred and thirty-one HCM patients (age, 50±16 years; 92 males and 39 females) with ≥1 HCM risk factor for sudden death underwent S-ICD ECG screening at rest and on exercise.

A multivariate time-frequency approach for tracking QT variability changes unrelated to heart rate variability.

The beat-to-beat variability of the QT interval (QTV) is a marker of ventricular repolarization (VR) dynamics and it has been suggested as an index of sympathetic ventricular outflow and cardiac instability. However, QTV is also affected by RR (or heart rate) variability (RRV), and QTV due to RRV may reduce QTV specificity as a VR marker. Therefore, it would be desirable to separate QTV due to VR dynamics from QTV due to RRV.

Effects and underlying mechanisms of refractory period pacing on repolarization dynamics in the human heart.

Repolarization alternans is related to the initiation of life threatening cardiac arrhythmias. Experimental and computational studies suggest that the abolishment of alternans using dynamic pacing protocols may prevent abnormal heart rhythms. In a recent animal study, refractory period pacing (RPP) on every other beat has shown promising results in alternans reduction.

Prognostic significance of exercise-induced premature ventricular complexes: a systematic review and meta-analysis of observational studies.

Background: Exercise-induced premature ventricular complexes (EI-PVCs) are common during exercise stress tests. Their optimal management and prognostic significance remain uncertain.

Aim: To perform meta-analysis of observational studies on the prognostic significance of EI-PVCs.

The Design of the Understanding Outcomes with the S-ICD in Primary Prevention Patients with Low EF Study (UNTOUCHED).

Background: The UNTOUCHED study will assess the safety and efficacy of the subcutaneous implantable cardioverter defibrillator (S-ICD) in the most common cohort of patients receiving ICDs. The primary goal is to evaluate the inappropriate shock (IAS)-free rate in primary prevention patients with a reduced ejection fraction (EF) and compare with a historical control of transvenous ICD patients with similar programming.

Methods And Results: The UNTOUCHED study is a global, multicenter, prospective, nonrandomized study of patients undergoing de novo S-ICD implantation for primary prevention of sudden cardiac death with a left ventricular EF ≤35%.

Long-Term Results of Triventricular Versus Biventricular Pacing in Heart Failure: A Propensity-Matched Comparison.

Objectives: The goal of this study was to assess the impact of triventricular pacing (Tri-V) on long-term survival.

Background: Biventricular pacing (Bi-V) is an important adjunctive treatment in advanced heart failure, but almost one-third of patients experience no improvement with this therapy and are labeled as nonresponders. Adding a third ventricular lead (Tri-V) has been shown to be feasible and provides favorable acute results when assessed by using echocardiographic, hemodynamic, and clinical endpoints.

Efficacy and safety of ablation for people with non-paroxysmal atrial fibrillation.

Background: The optimal rhythm management strategy for people with non-paroxysmal (persistent or long-standing persistent) atrial fibrilation is currently not well defined. Antiarrhythmic drugs have been the mainstay of therapy. But recently, in people who have not responded to antiarrhythmic drugs, the use of ablation (catheter and surgical) has emerged as an alternative to maintain sinus rhythm to avoid long-term atrial fibrillation complications.

Adenosine-guided pulmonary vein isolation versus conventional pulmonary vein isolation in patients undergoing atrial fibrillation ablation: An updated meta-analysis.

Background: Recurrent atrial fibrillation episodes following pulmonary vein isolation (PVI) are frequently due to reconnection of PVs. Adenosine can unmask dormant conduction, leading to additional ablation to improve AF-free survival. We performed a meta-analysis of the literature to assess the role of adenosine testing in patients undergoing atrial fibrillation (AF) ablation.

Medium-term outcomes of idiopathic ventricular fibrillation survivors and family screening: a multicentre experience.

Aims: Early repolarization (ER) has been linked to poorer outcomes in idiopathic ventricular fibrillation (IVF). The role of family screening in IVF is not clear. Our aim was to review predictors for poorer outcomes and evaluate the role of family screening in IVF.

Significance of neuro-cardiac control mechanisms governed by higher regions of the brain.

Advances in investigative techniques have led to an increasing awareness and understanding of the role of central neural control in the autonomic nervous system regulation of the heart. Substantial evidence exists for a role of the higher centres in neuro-cardiac control including the effect of focal brain stimulation and acute brain lesions on cardiac electrophysiology, blood pressure, contractile function and the development of arrhythmias. Mental stress and strong emotions have long been associated with sudden cardiac death.

Interactions between Activation and Repolarization Restitution Properties in the Intact Human Heart: In-Vivo Whole-Heart Data and Mathematical Description.

Background: The restitution of the action potential duration (APDR) and conduction velocity (CVR) are mechanisms whereby cardiac excitation and repolarization adapt to changes in heart rate. They modulate the vulnerability to dangerous arrhythmia, but the mechanistic link between restitution and arrhythmogenesis remains only partially understood.

Methods: This paper provides an experimental and theoretical study of repolarization and excitation restitution properties and their interactions in the intact human epicardium.

Ventricular Arrhythmia Burden in Patients With Heart Failure and Cardiac Resynchronization Devices: The Importance of Renal Function.

Background: Chronic kidney disease (CKD) is a risk factor for arrhythmias in patients with heart failure (HF). However, the effects of CKD on ventricular arrhythmia (VA) burden in patients with cardiac resynchronization therapy and defibrillator (CRT-D) devices in a primary prevention setting are unknown.

Objective: To determine whether baseline CKD is associated with increased risk of VA in patients implanted with primary prevention CRT-D devices.