When is myocardial mapping clinically valuable?

All cardiac arrhythmias are either automatic or reentrant. Automatic arrhythmias occur in the periinfarction or perioperative period. Chronic, recurrent arrhythmias are typically reentrant. By definition, reentrant arrhythmias are inducible with programmed electrical stimulation. When a malignant cardiac arrhythmia is identified, the patient is taken to the electrophysiologic laboratory for study. Reentrant ventricular tachyarrhythmias are induced with programmed electrical stimulation. Pharmacologic suppression is guided by electrophysiologic testing. When antiarrhythmic suppression fails, surgical intervention may be an effective alternative. Endocardial catheter mapping before surgery may serve as an important guide to the surgeon. Myocardial mapping is clinically valuable only when all antiarrhythmic therapy has failed, and the patient is considered to be a candidate for surgical intervention. When surgical intervention is planned, we consider preoperative catheter mapping desirable and intraoperative electrophysiologic localization mandatory.