Value of serial electropharmacological testing in managing patients resuscitated from cardiac arrest

Electrophysiologic studies were performed in 11 patients (9 men, 2 women; mean age: 59.9 yrs) who had survived an episode of cardiac arrest due to ventricular tachycardia (VT) or ventricular fibrillation. The purpose of the studies was to evaluate the usefulness of serial acute drug testing in selecting an effective chronic antiarrhythmic regimen. Ten of the patients were suffering from chronic ischemic heart disease with one or more previous myocardial infarctions while one had no evidence of structural heart disease. A ventricular aneurysm was present in four of them. During control electrophysiologic study, a sustained VT was induced by ventricular stimulation (single and double extrastimuli at various paced ventricular cycle lengths plus bursts of rapid ventricular pacing) in nine of the ten patients (90%) who were studied while not receiving antiarrhythmic drugs; a non-sustained VT was induced in one of them (10%). In three patients (30%) VT could be initiated only by right ventricular stimulation at a side different from the apex (outflow tract). No arrhythmia was observed in the only patient who was studied while taking amiodarone orally (400 mg/day for more than three months). During serial acute drug testing a totally effective drug regimen (successful in preventing the induction of any ventricular arrhythmia) was found in seven of the ten patients (70%) who underwent this procedure and a partially effective drug regimen (a sustained VT was no longer inducible; it was easier to interrupt and it was considerably slower) was found in two patients (20%). None of the nine patients who received chronic antiarrhythmic therapy based on the results of serial acute drug testing died suddenly during a mean follow-up of 14 months (range: 3-28) and only one had a recurrence of cardiac arrest. The latter, however, was taking antiarrhythmic drugs at a dosage less than that proved to be effective during electropharmacological testing. The only patient who refused serial acute drug testing and received an empiric antiarrhythmic therapy died suddenly at the 21st month of follow-up. These results indicate that serial electropharmacological testing is useful in selecting an effective long-term drug regimen in survivors of cardiac arrest.