Heart rate acceleration during cardioneuroablation is a weak predictor of significantly reduced parasympathetic modulation of sinus node

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Ablation of superior parasympathetic ganglia is associated with acceleration of sinus rhythm (SR). This has been considered a favorable sign during cardioneuroablation (CNA) for the treatment of functional bradyarrhythmias. Aim We studied whether the relative increase in SR frequency (DeltaSR) during CNA is a reliable predictor of significantly reduced parasympathetic modulation of the sinus node (SAN). Methods In patients undergoing CNA under general anesthesia, the gradual reduction in parasympathetic modulation of SAN during the procedure was assessed by extracardiac right vagal nerve stimulation (ECVS). The response to ECVS was quantified by the ratio of the maximum P-P interval (induced by ECVS) and the baseline SR cycle length (MaxPPratio). The ECVS was performed repeatedly after partial ablation steps, and therefore several pairs of DeltaSR and MaxPPratio values were obtained in the course of the single procedure. A MaxPPratio <1.5 was arbitrarily chosen as the criterion of significant attenuation of vagally induced responses. The optimum dichotomy of Delta-SR for the prediction of the MaxPPratio <1.5 was found according to the criterion of the minimum distance of the ROC curve from the point (0; 1). Results The study included 64 patients (mean age: 42 ± 16 years, 48% men). A total of 188 intraprocedural pairs of DeltaSR and MaxPPratio (2.9 ± 2.1 pairs per procedure) covering the wide distribution of their values (19 ± 14 bpm for DeltaSR and 2.9 ± 2.8 for MaxPPratio) were obtained. One half of ECVS tests (51%) met the criterion of MaxPPratio <1.5. In the analysis of receiver operating characteristic, DeltaSR as a predictor of significantly reduced parasympathetic modulation of SAN showed an area under the curve (AUC) of 0.69 with 95% confidence interval (CI) of 0.62 - 0.77 (Figure). The optimum cut-off (DeltaSR ≥20 bpm) had a sensitivity (SENS), specificity (SPEC), positive (PPV), and negative predictive value (NPV) of 61%, 78%, 75%, and 66%, respectively. Conclusion Acceleration of SR during CNA is not a relevant surrogate of significantly reduced parasympathetic modulation of SAN. Elimination or significant suppression of responses of SAN to ECVS serves as an excellent procedural endpoint that might contribute to the favorable clinical outcome of the CNA.