Site of successful slow pathway ablation relates to clinical tachycardia rate in patients with atrioventricular nodal re-entrant tachycardia.

S low pathway ablation provides curative treatment for patients with atrioventricular nodal re-entrant tachycardia (AVNRT). The major concern remains the induction of complete atrioventricular (AV) block. To minimise the risk, many centres apply a stepwise approach, targeting initially inferoposterior sites of the septal annulus of the tricuspid valve. If the first ablation attempts are unsuccessful, the catheter is positioned at more medial and finally anterosuperior sites. Thus, the longest possible distance from the AV node is kept during energy delivery. Previous investigations suggest that the successful ablation site may be related to the conduction interval of the slow pathway. Since this interval is a determinant of the tachycardia cycle length, we hypothesised that the successful ablation site may be related to the heart rate during tachycardia. Such a finding would be important, since it would possibly allow a rough prediction of the successful ablation site and, thus, an approximate stratification of the risk of AV block based on ECG documentation of the tachycardia.