A higher than expected prevalence of AV nodal reentrant tachycardia in patients receiving implantable cardioverter-defibrillators

Background: Epidemiologic studies have indicated that the prevalence of paroxysmal supraventricular tachycardia (SVT) is approximately two to three of 1000 persons, of whom 50-60% have atrioventricular node reentrant tachycardia (AVNRT). Although SVT has been reported to account for a significant portion of inappropriate shocks in patients receiving implantable cardioverter- defibrillators (ICDs), the incidence of AVNRT is unknown. Objective: To define the incidence of AVNRT in patients with ICDs. Methods and Results: Of 426 patients followed with an ICD, 15 patients with AVNRT were identified (3.5%). AVNRT was noted preimplant in eight patients. One had remote AVNRT and had undergone radiofrequency (RF) ablation several years prior to ICD implantation. Three patients had known episodes and underwent RF ablation prior to ICD implant. Four had AVNRT induced at preimplant electrophysiology study and three had RF ablation prior to ICD implant. Seven patients had clinical episodes of AVNRT after ICD implant and six of seven received inappropriate ICD therapy for AVNRT. All seven patients underwent RF ablation for treatment of AVNRT. No patient who underwent RF ablation had further clinical episodes of SVT, and only one had further inappropriate ICD therapy for sinus tachycardia. Conclusion: The substantially higher prevalence of AVNRT in our followed ICD population (3.5%) compared to the general population may be due to detection bias or electroanatomic changes in the atrioventricular nodal area induced by the accompanying heart disease. In any case, further studies to evaluate the inducibility of AVNRT prior to ICD implant, its prognostic implications, and the role of RF ablation to prevent inappropriate shocks are warranted.