Role of Electrophysiologic Testing in the Therapy of Ventricular Arrhythmias

The past decade has witnessed important advances in the understanding of the mechanism underlying ventricular arrhythmias. It has become clear that sustained ventricular arrhythmias can generally be reproduced with programmed ventricular stimulation in the clinical electrophysiology laboratory. False positive results may, however, occur with very vigorous stimulation techniques, particularly in patients without documented arrhythmias. False negative results are not infrequent in victims of cardiac arrest. Ability or inability to initiate ventricular tachycardia during acute and chronic drug testing has predicted clinical failure or success, at least for conventional antiarrhythmics. Patients with sustained ventricular tachycardia and cardiac arrest occurring outside the peri-infarction period are those most likely to benefit from study. Conventional antiarrhythmic agents are successful in about one-third of patients with a high degree of concordance among these drugs. Amiodarone is frequently effective in patients with drug-refractory ventricular arrhythmias. However, its efficacy cannot be predicted by programmed stimulation. This is in striking contrast to Type 1A anti-arrhythmic agents.