Congenital long QT syndrome

With an incidence as high as 1 in 2,000-2,500 live births, long QT syndrome (LQTS) is often characterized clinically by prolongation of the heart rate corrected QT interval (QTc) on a 12-lead surface electrocardiogram (ECG) and is associated with syncope, seizures, and sudden cardiac death due to ventricular arrhythmias usually following a precipitating event such as exertion, extreme emotion, or auditory stimulation. The phenotypic expression of LQTS varies profoundly from asymptomatic longevity to premature sudden cardiac death despite medical therapy. Therefore the clinical/genetic diagnostic evaluation and risk-stratification are highly important issues in the clinical management of LQTS. This chapter will review the historical background, epidemiology and prevalence, molecular genetics, and clinical presentations of LQTS, explore unique genotype - phenotype relationships that help define the various forms of the disorder, and provide a detailed outline for the diagnostic evaluation and clinical management of LQTS patients including current treatment strategies and recommendations.