Cryoablation for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is safe and efficacious. Information on the effects of cryoablation on atrioventricular (AV) nodal conduction is limited.The purpose of this study was to evaluate the effects of cryoablation on AV nodal conduction in pediatric patients with AVNRT.We retrospectively analyzed electrophysiologic studies before and after successful cryoablation. Patients were divided into two groups: group 1 (n = 22, age 14 +/- 3 years) had baseline discontinuous atrial-to-His interval (AH) conduction curves; and group 2 (n = 13, age 12 +/- 4 years, P = .054) had continuous curves.At baseline, group 1 had longer measurements of maximal AH with A1A2, AV nodal effective refractory period, and AV block cycle length. Postcryoablation, both group 1 and group 2 showed decreases in maximal AH with A1A2 pacing or atrial overdrive pacing and in the finding of PR > or = RR with atrial overdrive pacing (group 1: 55% vs 5%, P or = RR and with decreases in maximal AH with A1A2 pacing or atrial overdrive pacing. Further study is needed to determine the usefulness of these parameters for assessment of ablation efficacy or as proxies for AVNRT inducibility.