Ugurlu M, et al. - Given subclinical atrial fibrillation (SCAF) is relevant to issues such as the risk of stroke and the necessity of anticoagulant use in patients with cardiac resynchronization therapy (CRT), researchers sought to determine SCAF frequency and associated parameters in patients with CRT (77 females, 114 males, mean age 65.9 ± 9.8). SCAF was defined as asymptomatic atrial high-rate episodes (AHRE) longer than 6 min and shorter than 24 h. Compared with the normal population, a significantly higher frequency of SCAF was reported in patients with CRT. In the detection of patients to develop SCAF, the utility as well as the easy applicability of CHA₂DS₂-VASc score, left atrium diameter, and atrial threshold values were indicated.