INTRODUCTION: Conduction recurrence during radiofrequency (RF) ablation of cavotricuspid isthmus for typical atrial flutter is common. Understanding the temporal pattern of recurrences could help to predict a durable bidirectional block (BDB) and optimize the procedure. METHODS AND RESULTS: We analyzed atrial flutter ablations in 108 consecutive patients (85 males, age 63 +/- 11 years). RF energy was delivered through 8-mm tip or 4-mm cooled-tip catheter. On average, 18 +/- 11 pulses were necessary to achieve BDB. The time to recurrence of conduction after RF cessation was recorded. Early and late conduction recurrences were defined as < or =10 minutes and >10 minutes, respectively. Patients were observed for > or =30 minutes after bidirectional cavotricuspid isthmus (CTI) block was achieved. Conduction did not recur in 46 patients. In 8 cases, no block was achieved. A total of 167 conduction recurrences were recorded in the remaining 54 cases (1-10 per case). Of these, in 53 patients, recurrences were classified as early (98%) and 14 patients had late recurrences (8%). Thirteen patients had both early and late recurrences (24%). All but one late recurrence were preceded by at least one early recurrence. Absence of early recurrence had negative predictive value of 98%, while any early recurrence had positive predictive value of 26% for subsequent late conduction recovery. CONCLUSION: Incidence of isthmus conduction recurrence rapidly decayed during the waiting period. Absence of conduction recurrence within 10 minutes after first successful RF delivery was highly predictive of persistent BDB.

Charles University Hospital Department of Medicine 2 Prague Czech Republic