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