Abnormal atrioventricular node conduction and atrioventricular nodal reentrant tachycardia in patients older versus younger than 65 years of age.

STUDY OBJECTIVE: We examined the possible role of atrioventricular node (AVN) conduction abnormalities as a cause of AVN reentrant tachycardia (RT) in patients >65 years of age. STUDY POPULATION: Slow pathway radiofrequency catheter ablation (RFCA) was performed in 104 patients. Patients in group 1 (n = 14) were >65 years of age and had AV conduction abnormalities associated with structural heart disease. Patients in group 2 (n = 90) were <65 years of age and had lone AVNRT. RESULTS: Patients in group 1 versus group 2 (66% vs. 46% men) had a first episode of tachycardia at an older age than in group 2 (68 +/- 16.8 vs 32.5 +/- 18.8 years, P = 0.007). The history of arrhythmia was shorter in group 1 (5.4 +/- 3.8 vs 17.5 +/- 14, P = 0.05) and was associated with a higher proportion of patients with underlying heart disease than in group 2 (79% vs 3%, P < 0.001). The electrophysiological measurements were significantly shorter in group 2: atrial-His interval (74 +/- 17 vs 144 +/- 44 ms, P = 0.005), His-ventricular (HV) interval (41 +/- 5 vs 57 +/- 7 ms, P = 0.001), Wenckebach cycle length (329 +/- 38 vs 436 +/- 90 ms, P = 0.001), slow pathway effective refractory period (268 +/- 7 vs 344 +/- 94 ms, P = 0.005), and tachycardia cycle length (332 +/- 53 vs 426 +/- 56 ms, P = 0.001). The ventriculoatrial block cycle length was similar in both groups. The immediate procedural success rate was 100% in both groups, and no complication was observed in either group. One patient in group 2 had recurrence of AVNRT. One patient with a 98-ms HV interval underwent permanent VVI pacemaker implantation before RFCA procedure. CONCLUSION: In patients undergoing RFCA for AVNRT at >65 years of age had a shorter history of tachycardia-related symptoms than patients with lone AVNRT. The longer AVN conduction intervals and refractory period might explain the late development of AVNRT in group 1.