An Overview of Secondary Prevention Implantable Cardioverter-Defibrillator Trials: AVID, CIDS and CASH

Abstract

Sudden cardiac death, usually due to a ventricular tachyarrhythmia, accounts for 350,000–400,000 deaths annually in the United States. Less than 20% of patients will survive a cardiac arrest and be discharged alive from a hospital [1]. Of the survivors, 50% will be dead within 3 years [1]. Since survivors of a cardiac arrest are at high risk for a recurrent arrhythmic event, aggressive management of this group of patients is mandatory. Unfortunately, patients with previous sustained ventricular tachyarrhythmias only account for < 1% of patients who die suddenly. Given the high subsequent event rate and the low chance of surviving another cardiac arrest, there has been aggressive prescription of antiarrhythmic drugs, in an attempt to prevent arrhythmia recurrence, and of implantable cardioverterdefibrillators (ICDs), to successfully convert a sustained ventricular tachyarrhythmia [2]. Previous trials have suggested that amiodarone and sotalol are the most effective antiarrhythmic agents in patients with sustained ventricular tachycardia (VT)/ventricular fibrillation (VF). Antiarrhythmic approaches in these trials have included empirical and Holter/electrophysiologically guided use of these antiarrhythmic drugs [3]. One study of cardiac arrest survivors demonstrated that class I agents had a deleterious effect on survival [4]. In the same study [4], β-blockers improved survival. The benefits of β-blockers are supported by their known effects in prolonging survival in high-risk patients post-myocardial infarction (MI) or with congestive heart failure (CHF) [5].