Cardiac Contractility Modulation for Patients with Heart Failure

A substantial proportion of patients with heart failure remain either not eligible for cardiac resynchronization therapy (CRT) or do not respond to this therapy. CRT is indicated in patients with prolonged QRS duration (>120 ms). However, up to 60% of patients with heart failure have a normal QRS duration and are not appropriate candidates for CRT. In addition, a significant number of patients (25-30%) who meet the current indications to CRT therapy are non-responders. New device-based therapies including cardiac contractility modulation (CCM) have been developed over the last decade.

Drug-Induced Proarrhythmia: QT Interval Prolongation and Torsades de Pointes

Drug-induced torsades de pointes (TdP), a life-threatening polymorphic ventricular tachycardia associated with prolongation of the QT interval, has been the main safety reason for the withdrawal of non-cardiac agents from clinical use over the last decade. This complication is commonly referred to as drug-induced proarrhythmia. The present review highlights on the mechanisms underlying the drug-induced QT interval prolongation and TdP as well as on the identification of easily recognized risk factors that predispose to this potentially life-threatening condition

Catheter Ablation of Right Ventricular Outflow Tract Ventricular Tachycardia

Α 57-year-old female with repetitive monomorphic ventricular tachycardia was referred for an electrophysiological study. ECG during sinus rhythm was normal. ECG during tachycardia revealed a left bundle branch block (LBBB) pattern with inferior axis suggestive of an outflow tract tachycardia (Fig. 1). Structural heart disease was excluded. Transthoracic echocardiography and coronary angiography were unremarkable. The tachycardia was easily induced by atrial pacing (Fig. 2). This was suggestive of cyclic adenosine monophosphate (c-AMP) triggered activity as the pathophysiological basis of the arrhythmia. Activation mapping revealed the earliest activity at the posteroseptal region of the right ventricular outflow tract. A systolic pre-potential was recorded in this area, which is rarely seen in these type of arrhythmias (Fig. 3)... (excerpt

Current Ablation Strategies for Persistent and Long-Standing Persistent Atrial Fibrillation

Atrial fibrillation (AF) is associated with an increased risk of cardiac and overall mortality. Restoration and maintenance of sinus rhythm is of paramount importance if it can be accomplished without the use of antiarrhythmic drugs. Catheter ablation has evolved into a well-established treatment option for patients with symptomatic, drug-refractory AF. Ablation strategies which target the pulmonary veins are the cornerstone of AF ablation procedures, irrespective of the AF type. Ablation strategies in the setting of persistent and long-standing persistent AF are more complex. Many centers follow a stepwise ablation approach including pulmonary vein antral isolation as the initial step, electrogram-based ablation at sites exhibiting complex fractionated atrial electrograms, and linear lesions. Up to now, no single strategy is uniformly effective in patients with persistent and long-standing persistent AF. The present study reviewed the efficacy of the current ablation strategies for persistent and long-standing persistent AF

Electrocardiographic and Electrophysiologic Characteristics of Ventricular Extrasystoles Arising from the Aortomitral Continuity

Left ventricular outflow tract arrhythmias originating from the aortomitral continuity, the left coronary cusp, the superior basal septum, and the epicardial left ventricular summit display common electrocardiographic and electrophysiological features, probably due to the close proximity of those locations. Catheter ablation of these arrhythmias can be challenging. The case of a 68-year-old male with frequent premature ventricular extrasystoles arising from the aortomitral continuity of the basal left ventricle is described. The electrocardiographic and electrophysiologic characteristics of this arrhythmia are discussed

Catheter Ablation of Incessant Ventricular Tachycardia in a Patient With Coronary Artery Disease

A 67-year-old male with known coronary artery disease was referred to our hospital for catheter ablation of incessant ventricular tachycardia (VT). Transthoracic echocardiography revealed severe wall motion abnormalities of the left ventricle along with an apical aneurysm. Left ventricular voltage mapping showed a region with low voltage (<1.5 mV) at the left ventricular apex. Propagation mapping revealed a macro-reentry circuit around the apical aneurysm. Mid-diastolic potentials were recorded during the VT (Fig. 1, left panel, arrows), while entrainment mapping was excellent. The first radiofrequency energy application terminated the tachycardia. A circumferential lesion around the aneurysm was finally performed (Fig. 1, right panel, red dots). Ventricular tachycardia became non-inducible, and the patient is free from arrhythmic events during the last six months... (excerpt

QT and QU Interval Prolongation, Bidirectional Ventricular Tachycardia and Aborted Sudden Death. An Andersen-Tawil Syndrome

A 42-year-old lady survived an episode of near-drowning and she was subsequently diagnosed with a rare genetic disease, recently classified as long QT 7 syndrome, for which she received an implantable cardioverter defibrillator. The features of this syndrome are herein described

Notching early repolarization pattern in inferior leads increases risk of ventricular tachyarrhythmias in patients with acute myocardial infarction: a meta-analysis.

The aim of this of this meta-analysis was to examine the potential association between certain early repolarization (ER) characteristics and ventricular tachyarrhythmias (VTAs) in patients with acute myocardial infarction (AMI). We searched PubMed, Embase and Web of Science databases for records published until December 2014. Of the 658 initially identified records, 7 studies with a total of 1,565 patients (299 with ER and 1,266 without ER) were finally analyzed. Overall, patients with ER displayed a higher risk of VTAs following AMI compared to patients without ER [odds ratio (OR): 3.75, 95% CI: 2.62-5.37, p \u3c 0.00001]. Subgroup analyses showed that the diagnosis of ER prior to AMI onset is a better predictor of VTAs (OR: 5.70, p \u3c 0.00001) compared to those diagnosed after AMI onset (OR: 2.60, p = 0.00001). Remarkably, a notching morphology was a significant predictor of VTAs compared to slurring morphology (OR: 3.85, p = 0.002). Finally, an inferior ER location (OR: 8.85, p \u3c 0.00001) was significantly associated with increased risk of VTAs in AMI patients. In conclusion, our meta-analysis suggests that ER pattern is associated with greater risk of VTAs in patients with AMI. A notched ER pattern located in inferior leads confers the highest risk for VTAs in AMI

Machine learning techniques for arrhythmic risk stratification: a review of the literature

Ventricular arrhythmias (VAs) and sudden cardiac death (SCD) are significant adverse events that affect the morbidity and mortality of both the general population and patients with predisposing cardiovascular risk factors. Currently, conventional disease-specific scores are used for risk stratification purposes. However, these risk scores have several limitations, including variations among validation cohorts, the inclusion of a limited number of predictors while omitting important variables, as well as hidden relationships between predictors. Machine learning (ML) techniques are based on algorithms that describe intervariable relationships. Recent studies have implemented ML techniques to construct models for the prediction of fatal VAs. However, the application of ML study findings is limited by the absence of established frameworks for its implementation, in addition to clinicians’ unfamiliarity with ML techniques. This review, therefore, aims to provide an accessible and easy-to-understand summary of the existing evidence about the use of ML techniques in the prediction of VAs. Our findings suggest that ML algorithms improve arrhythmic prediction performance in different clinical settings. However, it should be emphasized that prospective studies comparing ML algorithms to conventional risk models are needed while a regulatory framework is required prior to their implementation in clinical practice