Electrophysiological testing has been used to identify patients with a substrate for ventricular arrhythmias and at high risk of SCA, though it has a limited role in general and is not routinely performed. In the presence of structural heart disease, inducible sustained monomorphic ventricular tachycardia with up to 3 ventricular extrastimuli at 2 drive cycle lengths is considered abnormal and associated with high risk of sudden cardiac death. However, a low risk of SCA cannot be inferred by the absence of inducible ventricular tachycardia. EPS also provides little prognostic data in patients with non-ischemic cardiomyopathy. Indeed, EPS has limited value in guiding therapeutic interventions in SCA survivors, as implantable cardioverter- -defibrillator is indicated in all survivors in the absence of specific contraindications.
Similarly, the failure to induce ventricular tachycardia does not obviate the need for implantable cardioverter-defibrillator in patients with ARVC and prior cardiac arrest. However, EPS in conjunction with voltage mapping can corroborate evidence of scar from imaging studies to support the diagnosis in ARVC and may identify patients at high risk of recurrent arrhythmia. EPS and ablation is indicated in patients with SCA and ventricular pre-excitation.