Role of pharmacotherapy in cardiac ion channelopathies

In the last decade there have been considerable advances in the understanding of the pathophysiology of malignant ventricular tachyarrhythmias (VA) and Sudden Cardiac Death (SCD). Over 80% of SCD occurs in patients with organic heart disease. However, approximately 10-15% of SCD occurs in the presence of structurally normal heart and the majority of those patients are young. In this group of patients, changes in genes encoding cardiac ion channels produce modification of the function of the channel resulting in an electrophysiological substrate of VA and SCD. Collectively these disorders are referred to as Cardiac Ion Channelopathies. The 4 major syndromes in this group are: The Long QT Syndrome (LQTS), the Brugada Syndrome (BrS), the Short QT Syndrome (SQTS), and the Catecholaminergic Polymorphic VT (CPVT). Each of these syndromes includes multiple subtypes with different and sometimes complex genetic abnormalities of cardiac ion channels. Many are associated with other somatic and neurological abnormalities besides the risk of VA and SCD. The current management of cardiac ion channelopathy could be summarized as follows: 1) in symptomatic patients, the implantable cardioverter defibrillator (ICD) is the only viable option; 2) in asymptomatic patients, risk stratification is necessary followed by the ICD, pharmacotherapy, or a combination of both. A genotype-specific approach to pharmacotherapy requires a thorough understanding of the molecular-cellular basis of arrhythmogenesis in cardiac ion channelopathies as well as the specific drug profile.