Key Clinical Questions
What is the clinical and prognostic significance of frequent premature ventricular complexes (PVCs) and nonsustained ventricular tachycardia (NSVT), and how should they be managed?
In the setting of a wide-complex tachycardia (WCT), what features favor a diagnosis of ventricular tachycardia (VT)?
What types of ventricular tachycardia or ventricular fibrillation (VF) can occur in the absence of structural heart disease and what types can be precipitated by exercise?
How should a clinician distinguish between stable VT, unstable VT, and pulseless VT diagnostically and therapeutically?
Which patients deserve implantable cardiodefibrillators (ICDs) for primary or secondary prevention of sudden cardiac death (SCD), and what is the role of antiarrhythmic drug therapy in primary and secondary prevention of SCD?
Ventricular arrhythmias are a heterogeneous group of cardiac rhythm disturbances that range from benign, asymptomatic premature ventricular complexes (PVCs) to malignant and often fatal arrhythmias, such as ventricular fibrillation (VF). They can occur both in the absence and presence of overt heart disease and have a wide spectrum of clinical significance and prognostic implications. The risk of sudden cardiac death (SCD) with some of these arrhythmias has led the medical community to identify patients susceptible to such events, and thus justify potentially dangerous and expensive treatments. Evidence gathered from clinical trials in the last three decades has helped establish clear epidemiological patterns for most types of ventricular rhythm abnormalities. These patterns have proven to be vital in the development of widely accepted, evidence-based guidelines for therapy and prevention.
The purpose of this chapter is to describe the epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and prevention of the most commonly encountered ventricular arrhythmias in current hospital practice. Care has been taken to include and cite evidence when appropriate. References to guidelines from the American College of Cardiology (ACC), American Heart Association (AHA), European Society of Cardiology (ESC), and the Heart Rhythm Society (HRS) are also found throughout the text.
PREMATURE VENTRICULAR COMPLEXES
INTRODUCTION AND EPIDEMIOLOGY
Premature ventricular complexes, also known as ventricular premature beats, ventricular extrasystoles, or ventricular premature depolarizations, are a frequent form of ventricular arrhythmia that occur both in the presence or absence of heart disease. Their prevalence depends on various demographic factors such as age, the presence or absence of heart disease, and the method used to detect them. In the Atherosclerosis Risk in the Community study, a review of over 15,000 healthy patients, the overall prevalence of any PVC on a 2-minute electrocardiogram (ECG) was 6% with a 34% rise for every 5-year increment in age. Conversely, published studies of healthy individuals evaluated with 24-hour ambulatory monitoring have found the prevalence of PVCs to be as high as 80%. In the background of acute myocardial infarction (AMI), the prevalence of PVCs may rise up to 93%.
Despite theoretical concerns of PVCs as a risk factor for heart disease, ...