SERIAL ELECTROPHARMACOLOGIC STUDIES IN PATIENTS WITH ISCHEMIC-HEART-DISEASE AND SUSTAINED VENTRICULAR TACHYARRHYTHMIAS - WHEN IS DRUG-TESTING SUFFICIENT

Serial testing of antiarrhythmic drugs by programmed electrical stimul ation can be costly in tine, expense and risk. The purpose of this stu dy was to evaluate the results of serial electropharmacologic tests fo r similarities that might obviate the need for protracted drug testing , Serial electropharmacologic testing was performed in 283 patients wi th coronary artery disease and clinical sustained ventricular tachycar dia (VT) or fibrillation (VF). Drug tests were defined as concordant i f sustained VT or VF could be consistently induced, or failed to be co nsistently induced during all such trials in a given patient. The foll owing drugs were included for testing: procainamide, quinidine and dis opyramide (class IA); phenytoin, mexiletine and tocainide (class IB); and flecainide and encainide (class IC). All patients were serially te sted with > 2 (mean and median, 3) antiarrhythmic agents regardless of results from drug-free testing or initial acute drug testing. Overall , the results of serial drug trials directed by programmed stimulation were concordant in more than two thirds of patients. Concordance was comparably high whether patients were serially tested with drugs withi n the same antiarrhythmic class, or with drugs from differing classes, and was not related to patients' clinical or electrophysiologic chara cteristics. Protracted serial electropharmacologic testing does not ap pear necessary for predicting successful or unsuccessful antiarrhythmi c drug therapy in survivors of clinical VT or VF. Single drug testing can identify most patients whose arrhythmia will or will not respond t o medications.