Day-to-day reproducibility of responses to right ventricular programmed electrical stimulation: implications for serial drug testing.

The day-to-day reproducibility of responses to right ventricular programmed electrical stimulation was analyzed in 77 patients studied in the baseline state twice within 72 hours. Of 66 in whom ventricular tachycardia (VT) was inducible at the first study (C1), VT was reproduced in 53 (80%) at the second control study (C2). Among 41 patients in whom VT was inducible using 1 or 2 programmed electrical stimuli (PES) at C1, VT remained inducible in 39 (95%) at C2, whereas only 14 of 25 patients (56%) who required 3 or more PES for VT induction at C1 had VT reproduced at C2. The difference in the reproducibility of VT induction in these 2 patient groups was highly significant (p less than 0.001). Although VT was inducible in 50% of patients using the identical stimulation mode at each study, 35% required a more intense mode for VT induction at C2; this included 11 of 35 patients (31%) in whom VT was initially inducible with 1 or 2 PES who required 3 or more PES for induction of VT at C2. Thus, patients in whom VT is initially inducible with 1 or 2 PES demonstrate reproducible day-to-day responses to programmed electrical stimulation and appear to be excellent candidates for electrophysiologically guided antiarrhythmic drug therapy. Because VT induction was significantly less reproducible in patients who required 3 or more PES at C1, day-to-day reproducibility of VT induction should be confirmed in such patients if electropharmacologic therapy is attempted.(ABSTRACT TRUNCATED AT 250 WORDS)