Discussion

To our knowledge, this is the first study to compare the different radiofrequency ablation catheters in AVN ablation. Patients were elderly with multiple comorbidities. The procedure was highly successful with no immediate complications. HPSD catheter was significantly shorter compared with the plain catheter.
The main current indication for AVN ablation is atrial tachyarrhythmias that are resistant to other treatment modalities, especially in the elderly population(16, 17). Two large trials assess the role of AVN ablation in resistant atrial tachycardia. In the ablate and pace trial, 156 with resistant atrial fibrillation had AVN ablation with permanent pacemaker placement. After the procedure, patients had improved quality of life and improved left ventricular function (18). In patients with heart failure and symptomatic AF, AVN ablation with cardiac resynchronization (CRT) reduced HF-related hospitalization and improved quality of life(19). As in previous research, our population was elderly with several comorbidities. The indication was atrial tachyarrhythmia resistant to medical therapy, mainly atrial fibrillation(74%). We assessed the short-term effectiveness of the procedure with no data on long-term effects.
The procedure is typically highly successful with a low complication rate. The overall success rate is above 97%(16). In our study, all procedures were successful with no immediate complications. We could not assess for factors associated with procedure success/failure as we had no failed ablation.
Ablation catheters have advanced in the design to improve safety and effectiveness. Several new catheters were introduced, including irrigated and contact force catheters. Several studies and systemic reviews compared the safety/effectiveness of different catheters in atrial fibrillation ablation(20-22). Studies in atrial fibrillation favored HFSD in success rate and procedure time(23-25). Direct current energy was used in the early stages but was soon replaced by radiofrequency due to better safety and effectiveness (16). Few/no studies compared different radiofrequency ablation catheters in AVN ablation. In our study, a contact force catheter with HPSD settings was significantly associated with lower lesion time by 403.42s[-631.67, -175.17]. The success rate was similar to other catheters(all successful) with no immediate complications.
Current medical practice has increasing complexity with introducing new management modalities. Comparative effectiveness research is essential to improve the quality of care and guide policymakers, clinicians, and patients in deciding on their care(26). Our study has several limitations. First, procedures were done by different operators, which could confound our results. Differences in lesion time could be related to different expertise levels between different operators. Another limitation was the short follow-up time. There were no immediate post-procedure complications. However, no data regarding long-term safety and efficacy were available. We had no data regarding long-term patient outcomes such as morbidity, mortality, and quality of life. Complications are likely to occur in the immediate post-procedure time; as a result, we likely to document the severe complications that would happen. The main aim of the study was to compare different radiofrequency ablation catheters. Data regarding the long-term effect of AVN ablation is needed; however, that was not the focus of our research. It is unlikely that the long-term effects would be related to the type of catheter used.