Does electrophysiological testing have any role in risk stratification for sudden cardiac death?

Implantation of implantable cardioverter defibrillators (ICD) has widely been accepted for secondary prevention of sudden cardiac death (SCD) in cardiac arrest survivors.1 Currently there are increasing interests in primary prevention of SCD in selected high risk patients who have not experienced cardiac arrest.1 Despite extensive investigation for risk stratification, our current ability to accurately identify patients at high risk for SCD remains very poor. The primary reason is probably due to our limited understanding of the mechanisms underlying the pathogenesis of ventricular tachy-arrhythmias and sudden cardiac death (Fig.1). Although ventricular tachycardia (VT) or fibrillation (VF) is still considered the most common mechanism of SCD in patients with advanced heart failure, many causes other than VT/VF (such as bradycardia) may account for up to 50% of SCD, particularly in non-ischemic dilated cardiomyopathy (DCM).