PO-02-031 FEASIBILITY OF NONINVASIVE TRAGAL STIMULATION TO ASSESS VAGAL TONE DURING CARDIONEUROABLATION

Abstract

There is increasing evidence that cardioneuroablation (CNA) can be an effective treatment for patients with atrial fibrillation and vasovagal syncope. The optimal procedural endpoint for CNA is unknown but elimination of response to invasive vagal stimulation has been utilized. To characterize the ability of transcutaneous tragal stimulation to non-invasively assess vagal tone before and after CNA as a potential procedural endpoint. We conducted a prospective, single center study in patients undergoing CNA as part of an ablation for atrial fibrillation. Transcutaneous tragal stimulation (left, right, then bilateral) was performed using Parasym vagal stimulator (20Hz, up to 42mA, up to 10 seconds) to identify vagal response. Positive response was defined as >2 seconds ventricular asystole, AV block or >10% increase in P-P or R-R interval. Stimulation was performed at baseline and repeated immediately following the CNA portion of the procedure. Among 19 patients, 9(47%) were male, median age was 70.7 years (IQR 66.9-70.7), median CHA2DS2Vasc score was 3(IQR 2.5-4). Atrial fibrillation was paroxysmal in 13 patients (68%), 11 patients (58%) were on antiarrhythmic therapy and 6 patients (32%) had prior ablations for atrial fibrillation. Response to bilateral stimulation was noted in 2 patients and only to left tragal stimulation in 1 patient. The response in these patients was a median increase in the PP interval by 350ms (IQR 310 – 370) or 31% (IQR 29 – 44) without an increase in the PR interval noted in any patient. No response to stimulation was seen after CNA in these 3 patients. Among all patients, median heart rate (HR) increase after CNA was 19 bpm (IQR 14-36, p=0.0001) and the PR interval decreased by a median of 15ms (IQR 9.5-41, p=0.0024). Changes in HR and PR interval was seen in both patients with tragal stimulation response (HR increase median 26 bpm and PR decrease median 36ms) and without response to tragal stimulation (HR increase median 15 bpm and PR decrease median 14 ms). High output tragal stimulation was inconsistently able to produce identifiable increase in vagal tone. When identified, elimination of response may be a reliable indicator of effective CNA, however the low response rate limits its utility. The poor efficacy observed may be due to the limited tragal innervation of the vagus nerve and alternative stimulation sites, such as the auditory canal should be considered.Tabled 1Table 1Baseline Characteristicsn=19Age (years) median (IQR)70.7 years (67-73.3)Male gender n (%)9 (47%)Prior historyHypertension n (%)14 (73%)Obstructive Sleep Apnea n (%)4 (21%)Diabetes n (%)5 (26%)Congestive Heart Failure n (%)3 (15%)Coronary artery disease n (%)7 (37%)Cerebrovascular disease n (%)1 (5%)Peripheral arterial disease n (%)2 (10%)CHA2DS2Vasc median (IQR)3 (2.5-4)Atrial Fibrillation detailsParoxysmal n (%)13 (69%)Persistent n (%)6 (32%)Vagally mediated AF n (%)8 (42%)Coexisting Atrial Flutter n (%)6 (32%)Antiarrhythmic drugs11 (58%)Prior ablation n (%)6 (32%)Echocardiographic featuresLeft Ventricular Ejection Fraction (%) median (%)60 (55-65)Normal Left atrial size n (%)4 (21%)Severe Left atrial dilatation n (%)1 (5%)Tragal Stimulation responseLeft tragal response n (%)1 (5%)Bilateral tragal response n (%)2 (10%)ΔPP interval pre-ablation (msec) median (IQR)350ms (IQR 310 – 370)Post Cardioneuroablation responseΔHeart rate post-ablation (bpm) median (IQR)18.5bpm (IQR 13.5 to 35.5)ΔPR interval post-ablation (msec) median (IQR)-15ms (IQR -9.5 to -41) Open table in a new tab