Antiarrhythmic drug therapy in the Multicenter UnSustained Tachycardia Trial (MUSTT): Drug testing and as-treated analysis

Objectives Using data from the Multicenter UnSustained Tachycardia Trial (M USTT), we examined the factors used to select antiarrhythmic drug therapy a nd their impact on outcomes. Background The MUSTT examined the use of programmed ventricular stimulation (PVS) to guide antiarrhythmic therapy in patients with coronary arterioscl erosis, left ventricular dysfunction and asymptomatic, unsustained ventricu lar tachycardia (Vf). Trial outcomes may reflect factors used to select ant iarrhythmic drug therapy. Methods We compared subgroups of patients with inducible sustained VT rando mized to PVS-guided antiarrhythmic therapy (n = 351), in particular those r eceiving PVS-guided antiarrhythmic drug therapy (n = 142) versus no antiarr hythmic therapy (controls, n = 353). Results "Effective" antiarrhythmic drug therapy (i.e., the terra "effective " was used to denote therapy that resulted in noninducible VT or hemodynami cally stable induced VT) was found for 142 of the 351 patients (43%), most often at the first ur second PVS session (125/142, 88%). Mortality among th e 142 patients did not differ from that among control patients. Of these 14 2 patients, the PVS end point was noninducibility in 91 patients and stable VT in 51 patients. Mortality did not differ between these two groups eithe r, but arrhythmia was numerically more frequent in the PVS-induced stable V T group. Mortality was greatest in the few patients receiving propafenone ( unadjusted p = 0.07, adjusted p = 0.14 vs. controls), but mortality with al l agents did not differ from that of controls even after adjustment. Conclusions Even when presenting the results as favorably as possible, we f ound no benefit with PVS-guided drug therapy in patients with clinical unsu stained VT who hod inducible sustained VT. These findings are unaltered by using different end points for PVS or considering the response to individua l drugs. (J Am Coll Cardiol 2001;38:344-51) (C) 2001 by the American Colleg e of Cardiology.