Genetic lipoprotein disorders and coronary atherosclerosis

Sudden Cardiac Death in the Young: A Strategy for Prevention by Targeted Evaluation

The annual incidence of sudden cardiac death (SCD) in the general population is estimated as 1 in a 1,000. Since survival rates from out-of-hospital cardiac arrests are poor, primary prevention is key to reducing the burden of SCD in the community. Prominent causes of SCD include ischaemic heart disease, anomalous coronary arteries, and the primary myocardial diseases: hypertrophic cardiomyopathy, dilated cardiomyopathy, and ar rhythmogenic right ventricular cardiomyopathy (ARVC). In 4% of sudden deaths in the 16-64 age group, post-mortem examination fails to identify a cause, yielding a default diagnosis of sudden arrhythmic death syndrome (SADS). The inherited arrhythmia syndromes (long QT, short QT, and Brugada syndromes, and familial catecholaminergic polymorphic ventricular tachycardia) may be implicated in SADS, owing to their propensity for producing ventricular tachyarrhythmia in the structurally normal heart. Monogenic disorders therefore predominate as causes of SCD in the young. The advent of effective therapies for these diseases, particularly implantable cardioverter defibrillators, has prompted calls for universal screening to enable timely diagnosis of occult cardiac disease. Since prospective cardiac assessment of the general population is not feasible, the solution may be to target high-risk subgroups, namely, patients with cardiac symptoms, relatives of SCD victims, and competitive athletes. The recommended preliminary work-up includes a 12-lead ECG, signal-averaged ECG, transthoracic echocardiogram, exercise test, and ambulatory ECG monitoring. Cardiovascular magnetic resonance is a useful adjunct in patients with suspected ARVC or anomalous coronary arteries. Provocative challenge with a sodium challenge blocker may be of value in unmasking the Brugada syndrome. Identification of disease-causing mutations in affected individuals facilitates cascade screening of families.