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 β‐stimulation. The number of EASs was determined by the Lumipoint™ 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 β‐stimulation (SVT/PAF/PsAF = 2.6 ± 1.0/1.3 ± 0.6/1.0 ± 0, p <.01). The number significantly increased with β‐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 β‐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 β‐stimulation than non‐AF patients. An elevated BNP level might predict subclinical SN dysfunction in patients with PAF. [ABSTRACT FROM AUTHOR]