Subcutaneous Lidocaine Affects Inducibility.A prospective study of 99 patients undergoing invasive electrophysiologic testing was conducted to determine whether the administration of lidocaine for local anesthesia influenced the inducibility of arrhythmias. Of the 99 patients, 42 had inducible arrhythmias. Multiple stepwise discriminant analysis indicated that the most important factor influencing inducibility was lidocaine dosage per weight, with a calculated cutoff of 3.2 mg/kg. There were 26/54 (48%) of patients who had no inducible arrhythmias below the cutoff, compared with 31/45 (69%) above the cutoff (P3.2 mg/kg and serum concentration above 1.4μg/mL (therapeutic range 1‐5μg/mL) 1 hour after administration, 18 had no inducible arrhythmias (86%). Younger, smaller patients were more affected (P1.4μg/mL, failure to induce may be sus