INTRODUCTION AND EPIDEMIOLOGY
This chapter focuses on the epidemiology and pathophysiology of sudden cardiac death in adults and strategies for prevention and treatment. Discussions of sudden infant death syndrome and cardiac arrest in children are found in chapter 126, Congenital and Acquired Heart Disease, and chapter 127, Syncope, Dysrhythmias, and ECG Interpretation in Children. Chapters 22 and 23 discuss basic and advanced life support, respectively. Chapters 23 and 33 discuss defibrillation and cardioversion, and cardiac pacing, respectively.
Sudden, unexpected out-of-hospital cardiac arrest occurs in approximately 382,800 adult Americans each year.1 Estimated national survival of EMS-treated cardiac arrest cases is 11.4%, yielding an estimated overall out-of-hospital cardiac arrest survival rate of 6.8% (EMS-treated plus deceased-on-EMS-arrival cases).1 There is substantial variability in the odds for survival across various geographic locations.2
Most episodes of sudden cardiac death occur in the home, although victims who experience cardiac arrest in a public place have a much better chance of survival.3 The initial recorded cardiac arrest rhythm is more likely to be ventricular fibrillation when cardiac arrest occurs in a public location rather than in the home, likely because patients who experience cardiac arrest in the home are typically older and more likely to have one or more chronic diseases that limit or exclude participation in activities outside the home.3 Sudden cardiac death is 30% to 80% higher among residents in the lowest compared with the highest socioeconomic quartile.4 This association is likely due to lifestyle and healthcare disparity issues.
There is a circadian pattern of sudden cardiac death and acute myocardial infarction,5,6 and both are most likely to occur within the first few hours after awakening from sleep, when there is increased sympathetic stimulation. β-Blockade provides some protection from sudden cardiac death, particularly in patients with known coronary artery disease who have had myocardial infarction and have a low ejection fraction.7
There are two peaks in the age-related prevalence of sudden cardiac death: infancy (representing sudden infant death syndrome) and age greater than 45 to 50 years, with 60% in males.4 There are multiple known factors contributing to the likelihood of sudden cardiac death (Table 11-1).
Table 11-1Known Factors Contributing to the Likelihood of Sudden Cardiac Death ||Download (.pdf) Table 11-1 Known Factors Contributing to the Likelihood of Sudden Cardiac Death
Coronary artery disease
Severe left ventricular dysfunction
Arrhythmogenic right ventricular cardiomyopathy
Congenital heart disease, especially coronary artery anomalies
Valvular heart disease
Cardiac pacemaker and conducting system disease
Early repolarization syndrome (ERS)
Long QT syndrome (LQTS)
Short QT syndrome (SQTS)
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
Risk factors and triggers
Long-term risk factor management
Unstable atherosclerotic plaque