Lars Eckardt

Prolonged atrial action potential durations and polymorphic atrial tachyarrhythmias in patients with long QT syndrome.

Introduction: Prolongation of the QT interval and torsades de pointes tachycardias due to altered expression or function of repolarizing ion channels are the hallmark of congenital long QT syndrome (LQTS). The same ion channels also contribute to atrial repolarization, and familial atrial fibrillation may be associated with a mutated KVLQT1 gene. We therefore assessed atrial action potential characteristics and atrial arrhythmias in LQTS patients.

Prevalence of supraventricular tachyarrhythmias in a cohort of 115 patients with Brugada syndrome.

Background: The Brugada syndrome is characterized by ST segment elevation in leads V1 to V3 and a right bundle branch block like pattern. It is associated with an increased risk of syncope and sudden cardiac death. Initial reports in small numbers of patients suggest an association between supraventricular tachycardias and Brugada syndrome with a prevalence varying between 13% and 40%.

Phytanic Acid Accumulation Is Associated with Conduction Delay and Sudden Cardiac Death in Sterol Carrier Protein-2/Sterol Carrier Protein-x Deficient Mice

Introduction: The sterol carrier protein‐2 gene encodes two functionally distinct proteins: sterol carrier protein‐2 (SCP2, a peroxisomal lipid carrier) and sterol carrier protein‐x (SCPx, a peroxisomal thiolase known as peroxisomal thiolase‐2), which is involved in peroxisomal metabolism of bile acids and branched‐chain fatty acids. We show in this study that mice deficient in SCP2 and SCPx (SCP2null) develop a cardiac phenotype leading to a high sudden cardiac death rate if mice are maintained on diets enriched for phytol (a metabolic precursor of branched‐chain fatty acids).

Gender differences in Brugada syndrome.

The syndrome of right bundle branch block, ST segment elevation in V1–V3, and sudden death, named Brugada syndrome from 1996 onward, has attracted great interest. Arrhythmic events tend to occur from the fourth decade onwards, with notable exceptions at both ends of the age spectrum. Absence of structural heart disease is believed to be part of the disease definition, although there is evidence that right ventricular fibrosis may occur.1 Apparently normal hearts revealed structural alterations on endomyocardial biopsies at noninvasive evaluation.2

Divergent Effect of Acute Ventricular Dilatation on the Electrophysiologic Characteristics of d,I‐Sotalol and Flecainide in the Isolated Rebbit heart

Ventricular Dilatation and d,l‐Sotalol/Flecainide in Isolated Rabbit Heart. Introduction: The interaction between acute ventricular dilatation (AVD) as one aspect of ventricular dysfunction and Class I and III antiarrhythmic drugs is uncertain. We therefore investigated the effects of AVD on the electrophysiologic properties of d,l‐sotalol and flecainide.

T Wave Alternans Does not Assess Arrhythmic Risk in Patients with Brugada Syndrome

Background: Brugada syndrome is associated with a risk for sudden death, but the arrhythmic risk in an individual Brugada syndrome patient is difficult to predict. Pathologic changes in the early repolarization phase of the ventricular action potential probably constitute part of the arrhythmogenic substrate in Brugada syndrome. Microvolt T wave alternans (TWA) assesses dynamic beat‐to‐beat changes in repolarization and has been suggested as a marker for repolarization‐related sudden death. We therefore tested whether TWA is an indicator for arrhythmias in Brugada syndrome with a focus on right precordial ECG leads.

Totally Subcutaneous Implantable Cardioverter Defibrillator with an Alternative, Right Parasternal, Electrode Placement

The totally subcutaneous implantable cardioverter‐defibrillator (S‐ICD) is an entirely novel defibrillation device that avoids the direct contact of device electrodes with the heart and the cardiovascular system. Here, we present a particular case of a young woman with congenital long‐QT syndrome in which we implanted the electrode alternatively, right parasternally. This decision was based on the thoracic anatomy of the patient and on findings of a model of S‐ICD electrodes in an adult torso. In conclusion, in some patients an alternative subcutaneous electrode position may be carefully considered but should not be taken to outweigh the standard left‐sided placement. (PACE 2012; 35:e254–e257)

Ranolazine and Vernakalant Prevent Ventricular Arrhythmias in an Experimental Whole-Heart Model of Short QT Syndrome

Ranolazine has been reported to have an antiarrhythmic potential. The aim of this study was to assess the electrophysiologic effects of ranolazine and to compare its effects to vernakalant in an experimental whole‐heart model of short‐QT syndrome.

Catheter Ablation of Stable Ventricular Tachycardia Before Defibrillator Implantation in Patients with Coronary Heart Disease (VTACH): An On-Treatment Analysis

In the Ventricular Tachycardia Ablation in Coronary Heart Disease (VTACH) study, an intention‐to‐treat approach was used and may have diminished the observed degree of treatment effect. We present a subanalysis of the VTACH study by treatment actually received.

A new experimentally validated formula to calculate the QT interval in the presence of left bundle branch block holds true in the clinical setting.

The evaluation of the QT interval in the presence of left bundle branch block (LBBB) is associated with the challenge to discriminate native QT interval from the prolongation due to the increase in QRS duration. The newest formula to evaluate QT interval in the presence of LBBB suggests: modified QT during LBBB = measured QT interval minus 50% of LBBB duration. The purpose of this study is therefore to validate the abovementioned formula in the clinical setting.