Similarly, the found that an AHRE burden of 5.5 h in a day, in a 30-day period, was associated with a twofold increase in the adjusted risk of stroke (absolute risk of thromboembolism around 1.8% per year).383 Integration of AHRE presence, duration, or burden ($ 5 min or $ 24 h) into risk scores for thromboembolism may modestly improve c-statistics of both the CHADS2 and CHA2DS2-VASc scores for predicting stroke.389 The clinical signi cance of AHRE is presumably different from that of clinically identi ed AF since the latter, detected using conventional surface ECG methods, corresponds to a much higher AF burden as compared with patients with AHRE detected by continuous monitoring via a CIED.370,372 The actual rates of stroke or systemic embolic events reported in studies evaluating CIED-detected AHREs are often lower than what would be predicted by CHADS2 and CHA2DS2-VASc scores, and this may be related to concurrent treatment with OACs in each study, risk of under-reporting, and confounding. Also, the temporal relationship between ischemic stroke and AF is less strict than expected, since stroke may occur without the concurrent presence of atrial tachyarrhythmias or AF at the time of stroke or in the days before. 