Subclinical Sinus Node Dysfunction in Patients with Atrial Fibrillation—insight from Ultrahigh‐resolution Mapping of Human Sinoatrial Exits

Background Even a short duration of paroxysmal episodes of atrial fibrillation (AF) is associated with sinus node (SN) remodeling and a reduced SN reserve or dysfunction. The number of earliest atrial activation sites (EASs) during sinus rhythm decreases according to the decrease in the SN reserve. Objective We sought to evaluate the EASs during sinus rhythm using an ultrahigh-density mapping system. Methods This study included 35 patients (supraventricular tachycardia [SVT]/paroxysmal atrial fibrillation [PAF]/persistent atrial fibrillation [PsAF] = 5/21/9) who underwent ultrahigh-resolution endocardial mapping of the SN area at rest and during beta-stimulation. The number of EASs was determined by the Lumipoint (TM) algorithm. Results The number of EASs was greatest in SVT patients both at rest (SVT/PAF/PsAF = 1.4 +/- 0.8/1.0 +/- 0/1.0 +/- 0, p = .04) and during beta-stimulation (SVT/PAF/PsAF = 2.6 +/- 1.0/1.3 +/- 0.6/1.0 +/- 0, p < .01). The number significantly increased with beta-stimulation as compared to baseline in the PAF patients (p = .02), but not in the PsAF patients. The brain natriuretic peptide (BNP) level was significantly higher in AF than SVT patients (SVT/PAF/PsAF = 12.3 [10.1-14.5]/25.7 [14.8-36.0]/73.4 [57.6-140] pg/ml, p < .01). In the PAF patients, the BNP level was significantly higher in those with unicentric EASs than multicentric EASs during beta-stimulation (28.1 [19.1-46.5] vs. 13.1 [9.4-26.9] pg/ml, p = .03), and the optimal cutoff point for the BNP level predicting unicentric EASs was 21.8 pg/ml (sensitivity 82.6%; specificity 85.7%). Conclusions AF patients have a smaller number of EASs and poorer response to beta-stimulation than non-AF patients. An elevated BNP level might predict subclinical SN dysfunction in patients with PAF.