Idiopathic Ventricular Fibrillation and Early Repolarization

In this chapter, an overview is provided on idiopathic ventricular fibrillation (IVF) and early repolarization. Idiopathic ventricular fibrillation is a tragic and notoriously difficult disease entity to manage. The IVF patients in whom a cardiac arrest occurs are generally considered healthy and do not show any currently identifiable abnormalities that denote their increased risk for malignant and life-threatening arrhythmias. Importantly, IVF can be inheritable and tear through families. The number of patients who survive their first manifestation of the disease is low, and the recurrence rate of IVF is appreciable. Treatment in patients who survived their event is performed by implantation of a cardioverter defibrillator (ICD) and a decrease of the risk of IVF recurrence may be achieved by prescription of quinidine. During a VF storm, administration of isoproterenol can be essential, and possibly also sedation might be effective. Research into the origin and genetic underpinning of IVF is limited by its malignant character, yet has revealed genetic variants in the DPP6 gene and CALM1 gene that impact on cellular cardiac electrophysiology. In contrast, early repolarization is a description of electrocardiographic variants with elevation, slurring, or notching in the terminal QRS complex or early ST segment. Although considered a benign electrocardiographic characteristic for many decades, in the past decade associations have been made with a propensity to sudden cardiac arrest by VF. Importantly, early repolarization is of very common occurrence in many young and healthy individuals. The description of a rare malignant association has spurred scientific interest in this phenomenon. Fortunately, its benign prognosis is still valid for the vast majority of individuals who display an early repolarization pattern. The challenge for the future will be to delineate benign from malignant variants of early repolarization, the development of aids in risk stratification and a better understanding underlying pathophysiology on cellular and genetic level, to further guide clinicians and patients.