Shock efficacy of appropriate episodes experienced by patients in the EFFORTLESS study. (A) Discrete episodes. The left-sided histogram provides first- and final shock efficacy over the course of the study for all rhythms and for episodes with monomorphic ventricular tachycardia or polymorphic ventricular tachycardia/ventricular fibrillation rhythms. The right-sided histogram provides first- and final shock efficacy for episodes experienced for each post-implant year. The number of episodes, number of patients, mean number of shocks delivered, and maximum number of shocks delivered are listed below each rhythm type (left histogram) and follow-up year (right histogram). Regression analyses show that neither duration of follow-up (P = 0.60) nor rhythm type (P = 0.28) significantly impacted first shock efficacy nor final shock efficacy (P = 0.62 and P = 0.82, respectively) for discrete episodes. (B) Storm episodes. The left-sided histogram provides efficacy over the course of the study for all storm episodes. The right-sided histogram provides shock efficacy for storm episodes experienced for each post-implant year. The numbers of patients and storm episodes are provided for each data column. Regression analysis showed that that neither duration of follow-up (P = 0.86) nor rhythm type (P = 0.93) significantly impacted shock efficacy for storm episodes. MVT, monomorphic ventricular tachycardia; PVT, polymorphic ventricular tachycardia; VF, ventricular fibrillation; Yr, year.