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Aims The early repolarization syndrome (ERS) can cause ventricular fibrillation (VF) and sudden death in young, otherwise healthy individuals. There are limited data suggesting that ERS might be heritable. The aim of this study was to characterize the clinical phenotype and to identify a causal variant in an affected family using an exome-sequencing approach. Methods and results Early repolarization syndrome was diagnosed according to the recently proposed Shanghai ERS Score. After sequencing of known ERS candidate genes, whole-exome sequencing (WES) was performed. The index patient (23 years, female) showed a dynamic inferolateral early repolarization (ER) pattern and electrical storm with intractable VF. Isoproterenol enabled successful termination of electrical storm with no recurrence on hydroquinidine therapy during 33 months of follow-up. The index patient’s brother (25 years) had a persistent inferior ER pattern with malignant features and a history of syncope. Both parents were asymptomatic and showed no ER pattern. While there was no pathogenic variant in candidate genes, WES detected a novel missense variant affecting a highly conserved residue (p. H2245R) in the ANK3 gene encoding Ankyrin-G in the two siblings and the father. Conclusion We identified two siblings with a malignant ERS phenotype sharing a novel ANK3 variant. A potentially pathogenic role of the novel ANK3 variant is suggested by the direct interaction of Ankyrin-G with the cardiac sodium channel, however, more patients with ANK3 variants and ERS would be required to establish ANK3 as novel ERS susceptibility gene. Our study provides additional evidence that ERS might be a heritable condition.

Introduction Parasystole refers to an ectopic pacemaker that discharges with a constant rate competing with the primary pacemaker of the heart the sinus node. Parasystolic pacemakers have been described in the atrium, atrioventricular node, His bundle, and in the ventricle. Ventricular parasystole usually carries a benign prognosis, but there are a few reports of ventricular tachyarrhythmia initiated by parasystolic beats. Case presentation We present a case of a 15-year-old otherwise healthy teenager with recurrent most likely arrhythmic syncope who was diagnosed with ventricular parasystole from the left posterior fascicle. After exclusion of structural and primary electrical heart disease, the patient was deemed at increased risk of parasystole-induced tachyarrhythmia, and thus catheter ablation of the ectopic focus was performed. Since catheter ablation the patient continues to be free of any symptoms. Discussion This report highlights the potential risks of parasystole in context of recurrent syncope and reviews the available literature on parasystole and ventricular tachyarrhythmia.

Aims The choice of left ventricular pacing configurations (LVPCs) of quadripolar leads used for cardiac resynchronization therapy (CRT) affects haemodynamic response and thus may be a tool for device optimization. The value of surface electrocardiograms and interventricular time delays (IVDs) for optimization is unknown. Methods and results Sixteen patients implanted with a CRT device with a quadripolar LV lead underwent invasive testing of LV d P /d t . QRS durations at baseline (bl) and during biventricular pacing (biv) were measured using different LVPCs (total of 141 LVPCs; 8.8 per patient). Variations in QRS duration during biv were calculated for each patient (ΔQRS) and, when compared with intrinsic QRS duration, for all LVPCs (ΔQRSLVPC). Interventricular time delays between the poles of the LV lead were obtained from intracardiac electrograms. ΔIVD was calculated as IVDmax − IVDmin. Parameters were correlated with LV d P /d t . ΔQRS and ΔQRSLVPC both significantly correlated with LV d P /d t ( P 168 ms ( P < 0.001), but not

In carriers of dual chamber pacemakers and implantable cardioverter-defibrillators (ICD), detection of atrial fibrillation (AF) is crucial for adequate mode switch function and to avoid inappropriate shock delivery. Detection algorithms rely on the atrial rate and on the relationship of atrial to ventricular intracardiac electrograms, but the relative portion of misclassified AF episodes remains high. Although myocardial impedance is a reliable indicator of contraction, little is known about atrial impedance as a marker of atrial arrhythmias. Methods During an electrophysiological study, we investigated the effect of induced AF on impedance at the right atrial free wall (RAFW) and right atrial appendage (RAA) in 20 patients. Using biphasic square-wave pulses (128 Hz, 200 microA/15 micros), impedance changes were recorded during sinus rhythm (SR-1), atrial pacing at 120 beats/min, AF induced by rapid atrial burst pacing, and after spontaneous AF termination (SR-2). Results At the RAA, peak-to-peak impedance amplitude during cardiac cycle (DeltaZ) dropped from 51.7 +/- 35.3 Omega (SR-1) or 49.6 +/- 30.6 Omega (pacing) to 24.6 +/- 22.0 Omega (AF, Por =0.0005), and subsequently increased to 37.7 +/- 24.7 Omega (SR-2, Por = 0.0004 v. AF). At the RAFW, DeltaZ changed from 16.2 +/- 15.5 Omega (SR-1) or 13.5 +/- 9.9 Omega (pacing) to 5.9 +/- 4.1 Omega (AF, Por = 0.003), and to 11.4 +/- 10.7 Omega (SR-2, Por = 0.015). Given a discrimination threshold of 65%, the sensitivity and the specificity of DeltaZ to detect AF were 79 +/- 18 and 89 +/- 14%, respectively (95% confidence interval).AF causes DeltaZ drop in pacemaker and ICD recipients. This impedance based algorithm can be used as an alternative method of AF detection.