Background and Purpose: Unlike clinical atrial fibrillation (AF), the significance of subclinical AF (SCAF) burden in patients with permanent pacemakers has not been fully evaluated. Methods: We investigated whether the SCAF burden was associated with increased risks of composite adverse outcomes, including progression to clinical AF, ischemic stroke, myocardial infarction, heart failure-related hospitalization, or cardiac death, in patients without previous AF. To quantify the 6-month SCAF burden, the total cumulative time spent in SCAF during every 6-month follow-up was summed. Results: During the median 5.2-year follow-up, 496 consecutive permanent pacemaker patients were classified into the no SCAF (no SCAF episode in any device analysis; n=152), low-burden SCAF (6-month SCAF <24 hours in at least one device analysis; n=287), or high-burden SCAF (6-month SCAF ≥24 hours in at least 1 device analysis; n=57) groups. The risk of composite adverse outcomes was greatest in the high-burden SCAF group ( P <0.001) and was primarily driven by progression to clinical AF ( P <0.001) and ischemic stroke ( P <0.001). The presence of high-burden SCAF, which always preceded ischemic stroke events, was independently associated with composite adverse outcomes (odds ratio=20.1 [95% CI, 7.60−52.7], P <0.001) and progression to clinical AF (odds ratio, 36.2 [95% CI, 15.9−87.8], P <0.001). Conclusions: In permanent pacemaker patients without preexisting AF, the presence of high-burden SCAF was closely associated with increased risks of composite adverse outcomes, particularly progression to clinical AF and ischemic stroke. Therefore, prospective studies deserve to be performed on the optimal anticoagulation therapy for permanent pacemaker patients with both high-burden SCAF and high stroke risk.

Background—: Fragmented QRS complex (fQRS) on 12-lead ECG, a marker of myocardial scar, is a predictor of arrhythmic events in patients with ischemic and nonischemic cardiomyopathy. We investigated whether the presence of fQRS is associated with the severity of the anomaly and with increased arrhythmic events in adult patients with Ebstein anomaly (EA). Methods and Results—: In 51 consecutive adult patients with EA (median age, 37 years; 18 males), the severity index of EA calculated from echocardiographic data and clinical arrhythmic events were analyzed. The extent of fQRS in each patient was measured by counting the number of ECG leads showing fQRS. There were 35 (68.6%) patients with fQRS (fQRS group) and 16 (31.4%) patients without fQRS (non-fQRS group). fQRS was observed more frequently in the inferior (n=26) and precordial (n=25) leads versus the lateral leads (n=5). The patients in the fQRS group had a worse functional class, greater cardiothoracic ratios, more severe tricuspid regurgitation, larger atrialized right ventricular areas, higher EA severity scores, and more frequent arrhythmic events compared with those in the non-fQRS group. The atrialized right ventricular area showed a positive correlation with the fQRS extent ( r =0.51; P <0.001). In multivariable Cox regression models, the presence of fQRS was independently associated with arrhythmic events ( P =0.036). Conclusions—: Fragmented QRS on 12-lead ECG was associated with larger atrialized right ventricular area and an increased risk of arrhythmic events in adult patients with EA.

Gwag HB, et al. Yonsei Med J. 2017 Jul;58(4):703-709. https://doi.org/10.3349/ymj.2017.58.4.703