Vagal AF Induction Test (VAFIT Protocol): A Novel Endpoint for
Optimizing Atrial Fibrillation Ablation Outcomes through
Cardioneuroablation
Abstract
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.