Optimal target temperature for slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia

Objective To define optimal target temperature for the slow pathway ablation.Materials and methods In this study, 268 patients with atrioventricular nodal reentrant tachycardia (190 females; mean age, 49 ± 14 years) who underwent slow pathway ablation using a combined electroanatomic approach were enrolled. The patients were categorized into Group 1 if target temperature was <55°C or into Group 2 if target temperature was ≥55°C. Group 2 was divided into three subgroups of 55°C (Sgp-1), 60°C (Sgp-2), and 65°C (Sgp-3).Results Acute success rate was similar in both groups (P = 0.83). The ablation time (26.2 ± 20 vs. 36.5 ± 28 min; P = 0.014), fluoroscopy time (11.6 ± 9.7 vs. 17.8 ± 16.6 min; P = 0.035), and number of applications (4.1 ± 3.2 vs. 9.1 ± 6.5; P = 0.02) were lower for Group 2 than Group 1 patients. The frequency of AV or VA block, impedance rise, and coagulum formation were comparable in two groups (all P > 0.05). During mean follow-up of 14 ± 3 months, recurrence of the arrhythmia was seen in higher proportion of Group 1 than Group 2 patients (P = 0.036). Among the Group 2 patients, there were no significant differences between the three subgroups in terms of acute success rate, fluoroscopy time, risks of AV and VA block, pericardial effusion, and recurrence (All P > 0.05). Number of applications and RF pulse duration were lower in Sgp-2 and 3 compared to Sgp-1 (All P > 0.05). Impedance rise and coagulum formation were slightly higher in Sgp-3 compared to Sgp-1 and 2 but this difference did not reach statistical significance (All P > 0.05).Conclusions Compared to less than 55°C, target temperatures ≥55°C during slow pathway ablation significantly reduces fluoroscopy time, RF pulse duration, number of RF applications, and recurrence of AVNRT without increase in risk of AV or VA block or coagulum formation.