Background and purpose: When atrial fibrillation (AF) is first documented at the time of onset of acute stroke, it is difficult to establish a temporal relationship between AF and stroke. Did AF precede and precipitate the stroke, or did the arrhythmia appear as a result of stroke? Following the course of the newly diagnosed AF may help to clarify this relationship.
Methods: The Framingham Study cohort of 5070 members, aged 30 to 62 years and free of cardiovascular disease at entry, has been under surveillance for the development of cardiovascular disease, including stroke. We followed the course of AF, which was documented for the first time on or soon after hospital admission for stroke.
Results: During 38 years of follow-up, 115 of 656 initial stroke events occurred in association with AF: 89 had previously documented AF, 21 had AF discovered for the first time on admission for the stroke, and 5 were admitted with sinus rhythm but developed AF after admission. Of the 21 subjects with AF diagnosed on admission, in 12 (57%) AF persisted thereafter (chronic AF). Among the other 9 persons presenting with nonpersistant AF, paroxysms recurred in 3 (14%) and became chronic AF in 4 (19%). AF was transient and did not recur in only 2 persons (10%). Of the 5 subjects who developed AF after admission, AF was sustained from the initial diagnosis in 2 and recurred in paroxysms or became established as chronic in 3.
Conclusions: Ninety-two percent (24/26) of subjects presenting with newly discovered AF at the time of acute stroke continued to have this rhythm disturbance in a chronic or paroxysmal form. In only 2 subjects (8%) was the arrhythmia short-lived and nonrecurrent. These follow-up data suggest that in most instances AF was probably the precipitant rather than the consequence of stroke.