Background Currently, there is no reliable endpoint for the conclusion of atrial fibrillation (AF) ablation. Atrial burst pacing and/or isoproterenol challenge are poor diagnostic tools. A newly proposed Vagal AF Induction Test(VAFIT) uses effective atrial refractory period measurement, simultaneously with extra-cardiac vagal stimulation(ECVS) to study AF inducibility pre and post-ablation. Objective Prospective study in patients submitted to radiofrequency catheter pulmonary vein isolation(PVI) plus cardioneuroablation(CNA) evaluating the VAFIT result before and at the end of the procedure with AF recurrence. Methods Prospective study of 142 patients, 57.5[48.9-70.2] years-old, 71% males, with symptomatic AF (79.6% paroxysmal/20.4% persistent), left atrium diameter of 38.0[35.0-41.2] mm, and left ventricular ejection fraction of 63.0 [62.0-68.2]. VAFIT was considered positive or negative depending on whether AF induction occurred. It was performed at baseline and after PVI+CNA, with a single atrial extra stimulus during ECVS (5s/50Hz/1V/kg up to 70V/Pulse Width=50 µs). Patients were followed for a median of 15.0[7.0-20.0] months. The association of VAFIT-positive status at the end of the procedure with AF recurrence was investigated by univariate and multivariate Cox regression analysis. Results Pre-ablation VAFIT was positive in all cases and became negative in 62.9% of patients. AF recurrence: 18.7% in VAFIT-positive and 5.6% in VAFIT-negative patients(p=0.012). VAFIT-positivity was associated with AF recurrence (HR: 4.56(1.37-15.23,p=0.014). Conclusion A VAFIT-positive status following PVI+CNA was strongly and independently associated with AF recurrence. It remains to be investigated in randomized studies whether achieving VAFIT-negativity at the end of the procedure, as demonstrated in this study, would lead to better clinical outcomes.

Background: The differential diagnosis of supraventricular tachycardias(SVTs) is essential during radiofrequency(RF) ablation. The Extracardiac Vagal Stimulation(ECVS), introduced in 2015, offers new insights for electrophysiologic studies and ablation by allowing a controlled vagal effect on the heart. Methods: A prospective study of 625 patients with SVT ablation indication. ECVS was performed using a regular electrophysiology catheter to study atrioventricular(AV) and ventriculo-atrial(VA) conduction and their effects on tachycardia. Baseline ECVS was performed to determine the optimal position for right or left ECVS, near the jugular foramen. ECVS was repeated during atrial and ventricular pacing(VP) to monitor the procedure’s progression and ensure successful endpoints. Results: ECVS was successful in 611/625 patients(98%), 381(62.3%) had AV node reentry tachycardia(AVNRT), and 230(37.6%) Accessory Pathway(AP), including 135(58.7%) manifest AP(WPW) and 95(41.3%) concealed AP. ECVS+VP in 33 patients with atypical AVNRT yielded VA block in 32(97%), suggesting VA conduction solely via the AV node. In contrast, 57 patients with concealed para-septal AP maintained VA conduction during ECVS, confirming AP. ECVS proved to be a fast, reliable, and practical additional EP tool: VA block indicated AVNRT, while persitent VA conduction suggested AP. Additionally, ECVS was highly effective in revealing and confirming successful AP ablation by demonstrating absence of AV and VA anomalous conduction. Conclusion: ECVS was a valuable tool in the diagnosis and ablation of SVTs. It allowed reproducible AV and VA block through normal pathways, easily identifying AVNRT and concealed, intermittent, or subtle AP. It was particularly useful in complex cases involving concealed AP and atypical AVNRT tachycardia.