Clinical significance of atrial high-rate episodes for thromboembolic events in Japanese population

Objective The clinical significance of atrial high-rate episodes (AHREs) detected by cardiac devices among patients with implantable pacemakers has recently emerged. However, the relationship between AHREs and ischaemic stroke and systemic embolism (SE) is not well understood in the Japanese population. Methods This study included 343 patients with pacemakers capable of continuous atrial rhythm monitoring (167 males; mean age, 80±7 years). Atrial tachyarrhythmia detection was programmed to the nominal setting of each device, and AHRE was defined as any episode of sustained atrial tachyarrhythmia lasting for more than 6 min. Thromboembolic risk was defined based on the CHADS2 score. Results During the follow-up period (52±30 months), 165 (48%) patients had at least one episode of AHREs, and 19 (6%) patients experienced stroke/SE. Among patients who experienced stroke/SE, 14 had AHREs before the stroke/SE. AHREs were significantly associated with stroke/SE (HR 2.87; 95% CI 1.10 to 8.90; p=0.03). Subgroup analysis conducted to investigate the impact of the CHADS2 score severity on stroke/SE revealed that AHREs were not associated with stroke/SE in patients with low or intermediate thromboembolic risk (CHADS2 score 0-2; n=217). In contrast, among patients with high thromboembolic risk (CHADS2 score>2; n=126), there was a significant association between AHREs and the incidence of stroke/SE (HR 3.73; 95% CI 1.06 to 13.1; p=0.04). Conclusion AHREs detected by pacemaker were associated with ischaemic stroke/SE in the Japanese population. However, this association was observed only in the high thromboembolic risk group.