Recent developments in the management of patients at risk for sudden cardiac death

Sudden cardiac death (SCD) due to ventricular tachyarrhythmias is an important cause of mortality in the United States, 4% of which occurs in patients with structurally normal hearts. At least some arrhythmias are caused by ≥ 1 mutation in 1 of the genes that control electrical conduction through the heart by altering calcium homeostasis or depolarization or repolarization gradients in the ventricle. Although SCD may be the first presentation, patients may often present with symptoms of palpitations or hemodynamic compromise, such as dizziness, seizure, or syncope, particularly following exertion. They may also be made aware of possibly having the condition due to symptoms in other family members. The primary care physician is ideally placed to investigate these symptoms, including detailed clinical and family histories and examining the baseline electrocardiogram. In all inherited cardiac death syndromes, first-degree relatives should be referred to a cardiologist, and should undergo testing appropriate for the condition. While management of patients at risk of SCD largely centers on risk stratification and, if necessary, insertion of an implantable cardioverter-defibrillator, there are a number of other treatments being developed. β-Blockers are often very effective in preventing arrhythmic episodes associated with catecholaminergic polymorphic ventricular tachycardia and some subtypes of long QT syndrome. In certain situations, calcium channel blockers may also be used. Quinidine and isoproterenol can be useful in treating Brugada syndrome. Left cervicothoracic stellectomy may occasionally be used in the treatment of long QT syndrome. As the genetic basis of these diseases becomes known, genetic testing is forming an increasingly important part of diagnosis, and gene-specific therapy is an area under investigation.