CHAPTER SUMMARY AND CENTRAL ILLUSTRATION
This chapter discusses the epidemiology and pathophysiology of sudden cardiac death (SCD), which is most often caused by ventricular arrhythmias, and addresses some of the key considerations for the evaluation and treatment of ventricular arrhythmias. Major risk factors for developing these arrhythmias include cardiac structural abnormalities and coronary artery disease (CAD) (see Fuster and Hurst’s Central Illustration). Moreover, a number of inherited channelopathies can predispose to these arrhythmias and should be considered in the context of a structurally normal heart. Ventricular arrhythmias can range from idiopathic premature ventricular complexes, to monomorphic ventricular tachycardia (VT), to ventricular fibrillation (VF). Management of ventricular arrhythmias requires a comprehensive approach that may involve multiple therapies, including an implantable cardioverter defibrillator (ICD), antiarrhythmic medications, catheter ablation, and/or autonomic modulation. The decision-making process for management depends highly upon the presence of underlying structural abnormalities.
eFig 37-01 Chapter 37: Ventricular Arrhythmias and Sudden Cardiac Death
Sudden cardiac death (SCD) is defined as an unexpected death resulting from a cardiac cause within a short time period after the onset of symptoms. It is most often caused by a sustained ventricular tachyarrhythmia (ventricular tachycardia [VT] and ventricular fibrillation [VF]). Although many cardiovascular disorders increase the risk of SCD, the presence of preexisting overt cardiovascular disease is not necessary, and SCD may be the first manifestation of otherwise phenotypically silent cardiac disease.
Ventricular arrhythmias commonly occur in clinical practice and range from benign asymptomatic premature ventricular complexes (PVCs) to sustained VT or VF resulting in SCD. The presence of structural heart disease plays a major role in risk stratification; however, it is important to recognize that potentially lethal arrhythmias can occur in structurally normal-appearing hearts. Management depends on the associated symptoms, underlying pathologic substrate, hemodynamic consequences, and associated long-term prognosis. Given the complexity of these arrhythmias, initial management, risk stratification, and treatment of ventricular arrhythmias pose a significant challenge to clinicians.
This chapter provides an overview of the epidemiology, mechanisms, clinical presentation, natural history, diagnosis, and therapeutic options for ventricular arrhythmias encountered in clinical practice.
Roughly half of all deaths due to cardiovascular disease are estimated to be due to SCD. Because 80% of sudden deaths occur in the home environment and up to 40% are unwitnessed, the cardiac rhythm that precipitated onset of symptoms are frequently unknown. Therefore, precise measurement of SCD rates and understanding of associated mechanisms is difficult. Estimates for SCD range between 180,000 and over 450,000 deaths yearly in the United States. Global estimates for the incidence of SCD range widely from 15 to 150 per 100,000 for adults age ≥18 years old, depending on the region.1 In autopsy-based studies, a cardiac etiology of sudden death has been reported in 60% to 70% ...