Conversion of sustained into nonsustained ventricular tachycardia during therapy assessment by programmed ventricular stimulation: criterion for a positive drug effect?

Serial electropharmacologic testing using up to 11 different antiarrhythmic drugs was performed in 130 consecutive patients (107 men, 23 women, ages 56 +/- 12) with inducible sustained ventricular tachycardia (VT). After 4 +/- 2.3 drug tests, complete suppression of VT inducibility (defined as less than 6 consecutive beats, mean 1.4 +/- 1.6) was achieved in 86 patients (66%), whereas in 44 patients (34%) nonsustained VTs (greater than or equal to 6 consecutive beats, less than 30 seconds in duration) were still inducible. There was no statistical difference between both groups regarding age, sex, underlying heart disease, ejection fraction or entry arrhythmia. After a mean follow-up period of 19 +/- 17 months, 24 patients (18%) had died, 8 (6%) suddenly. Eight patients (6%) experienced recurrent sustained VT. Symptomatic recurrences (sudden death or VT) occurred in 10 (11%) and 6 patients (13%, difference not significant), respectively. Probability of arrhythmia-free survival was comparable for patients with 0 to 5, 6 to 10, 11 to 15 and 16 to 32 inducible ventricular complexes with discharge medication. The negative predictive value of electropharmacologic drug testing was about 89%, irrespective of the maximal number of inducible complexes used for the definition of a negative test result. It is therefore concluded that conversion of sustained into nonsustained VT during therapy assessment by programmed ventricular stimulation indicates a positive drug effect.