Singer DE, Ziegler PD, Koehler JL, et al. - Findings demonstrate a temporal association of multihour episodes of atrial fibrillation (AF) with a transient increase in the risk of stroke among patients with cardiac implantable electronic devices (CIEDs); these results lend support to a study of time-delimited anticoagulation in patients with infrequent multihour episodes of AF.

• This is a case-crossover study of 891 patients with CIEDs and ischemic stroke with continuous monitoring in the 120 days prestroke.

• Odds ratio for stroke were estimated comparing AF during days 1 to 30 vs 91 to 120 prestroke.

• Multihour AF episodes increased the odds of stroke 3.7-fold for up to 30 days.

• Within 5 days of an episode of AF of 5.5 hours or more in duration, the excess stroke risk above baseline was found to be the highest (OR, 5.00) and diminished quickly thereafter.

• AF more than 23 hours on a given day was found to be related to the clearest elevation in stroke risk (OR, 5.00).

• The outcomes are consistent with the conventional view that there exists a direct and transient association of AF with ischemic stroke.