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Aims In the setting of atrioventricular nodal re-entrant tachycardia (AVNRT), radiofrequency (RF) catheter ablation of the slow-pathway (SP) ensures excellent outcome. However, the risk of complete heart block (CHB) remains real (≈1%) and detrimental. This study reports on a gradual power titration approach using RF energy, which allows a significant decrease in CHB occurrence. Methods and results Slow-pathway ablation was performed in 468 patients (mean age 43.8 ± 17.2 years, 311 women). Initial settings were 5 W, 60°C, 120 s (temperature-controlled mode). The power was increased by steps of 5 W for every 5 s until slow-accelerated junctional rhythm was obtained, and then further increased to 10 W maximum above this value. The acute success rate, the mean RF pulses applied per patient, and the average power delivered per successful RF applications were 99%, 3.2 ± 1.1, and 31.7 ± 3.0 W, respectively. There were nine (1.9%) transient and reversible AV blocks, and one (0.2%) permanent CHB only necessitating pacemaker insertion. The recurrence rate was 3.6% and the follow-up period was 28.1 ± 14.1 months. Conclusion Atrioventricular nodal re-entrant tachycardia RF ablation using gradual power titration is an efficient technique, capable of improving safety since it can decrease CHB occurrence.

To identify ECG predictors of Brugada type response during Na channel blockade challenge.We studied prospectively 103 patients (M = 76, 45 +/- 13 years) in whom ECGs were collected during ajmaline challenge. ECG recordings included the high right precordial leads (-2V(1) and -2V(2)). A positive response was defined by a0.2 mV J point or ST segment elevation and a down-sloping pattern of the ST segment in at least one right precordial lead.Ajmaline challenge was positive in 48 (47%) of the 103 cases. Baseline J wave elevation was greater in -2V(1) (0.077 +/- 0.078 mV vs. 0.038 +/- 0.046 mV, P = 0.003) and -2V(2) (0.149 +/- 0.103 mV vs. 0.043 +/- 0.088 mV, P0.001) in cases with a subsequent positive response. In contrast, ST segment elevation and T wave amplitudes were reduced in V(1), V(2) and V(3). Logistic regression showed that J wave elevation in -2V(2) and decreased T wave amplitude in V(3) at baseline were independent predictors of a positive response. Baseline J wave elevation0.16 mV in -2V(2) had a specificity of 100%, a sensitivity of 40%, a positive predictive value of 100% and a negative predictive value of 28%.J wave elevation0.16 mV in -2V(2) was the strongest predictor of a Brugada type response to Na channel blockade challenge when Brugada syndrome was suspected on a baseline ECG.