Sudden cardiac death (SCD) is defined as death from a cardiac cause that occurs suddenly (usually less than 1 hour) after the onset of symptoms. Most cases of sudden cardiac death are the result of ventricular arrhythmias, which may be the first manifestation of cardiac disease. Chest pain, palpitations, dyspnea, and syncope are common but non-specific prodromal symptoms associated with SCD.
About 400 000–460 000 people in the United States die from SCD each year, accounting for over 60% of all cardiac deaths. Despite the high age-adjusted incidence of SCD (206.5 per 100 000 men, 140.7 per 100 000 women, and 3.0 per 100 000 children and young adults aged ≤34 years), it has been a difficult condition to study thus far. In this chapter we review the etiologies of SCD, the tools used to identify and stratify individuals at risk, and strategies for risk reduction.
Etiologies of sudden cardiac death
Coronary artery disease
Because most cases of SCD (approximately 70%) occur in individuals with at least moderate coronary artery disease (CAD), it remains the most common risk factor for this condition. Individuals with a history of myocardial infarction (MI) have a 4- to 6-fold increased risk of SCD due in large part to postinfarction ventricular remodeling. Among patients with left ventricular dysfunction or heart failure, the risk of sudden death is highest (1.4% per month) in the first 30 days after an MI.5 Coronary artery disease is a less significant risk factor for SCD in young patients, as only about one fourth of young SCD victims have coronary artery disease.