ATRIOVENTRICULAR-BLOCK OCCURRING SEVERAL MONTHS AFTER RADIOFREQUENCY ABLATION FOR THE TREATMENT OF ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

Atrioventricular (AV) block following radiofrequency (RF) ablation for the treatment of AV nodal re-entrant tachycardia (AVNRT) is a rare bu t well recognised complication of the procedure-the reported incidence ranges from 1% to 21%. Almost all cases of AV block occur during or s hortly after the procedure, are transient, and recover quickly. Two pa tients (a 22 year man and a 72 year old woman) with symptomatic AV blo ck occurring several months after slow pathway RF ablation, requiring permanent pacemaker implantation, are described, Both patients had had several 24 hour Holter recordings before the procedure, and in neithe r case was there any evidence of intermittent or persistent AV block, This is a rare complication with no definitive predictors; however, al l efforts should be made to exclude AV block in patients presenting wi th suggestive symptoms following RF ablation. With the wide use of RF ablation for the treatment of AVNRT, more cases are likely to occur. A registry should allow documentation of the incidence of this complica tion.