Poster No. 135 Stroke risk of patients with new AF during ACS may depend on onset and duration

Newly diagnosed atrial fibrillation(AF) during acute coronary syndrome(ACS) is associated with worse outcomes. In this study we evaluated the associated stroke risk of newly diagnosed AF in ACS patients according to the onset and duration of the episode.

Amongst 4433 patients presenting with ACS, 439(9.9%) had newly diagnosed AF and 396(8.9%) had known AF. Of the new AF cases, 27.5% occurred post-CABG. The onset was within 24 hours of ACS presentation in 70.1% of non-CABG cases. The new AF episodes lasted longer than 24 hours in42.9% of the non-CABG cases. At discharge 54.0% of patients with new AF was treated with OAC, in contrast to 89.2% with known AF.

The incidence of ischemic stroke at one year was 1.2% in patients without AF, 1.0% with known AF, and 3.6% with new AF(P < 0.001). Within patients developing AF post-CABG, the incidence was 4/120(3.3%). Within non-CABG patients, the incidence of ischemic stroke for patients with onset within 24 hours of presentation was 0/133(0.0%) for patients with an episode lasting < 24 hours, and 6/109(5.5%) for patients with an episode lasting > 24 hours. For patients with new AF onset after 24 hours the incidence was 5/120(5.5%) for patients with an episode lasting < 24 hours, and 5/92(5.4%) for patients with an episode lasting > 24 hours.

Patients with newly diagnosed AF during ACS seem undertreated with OAC. The associated risk of ischemic stroke with new AF during ACS may be lower in episodes that terminate within the first 24 hours of presentation.