Stroke associated with atrial fibrillation--incidence and early outcomes in the north Dublin population stroke study

Abstract

Background: Prospective population-based studies are important to accurately determine the incidence and characteristics of stroke associated with atrial fibrillation (AF), while avoiding selection bias which may complicate hospital-based studies.

Methods: We investigated AF-associated stroke within the North Dublin Population Stroke Study, a prospective cohort study of stroke/transient ischaemic attack in 294,592 individuals, according to recommended criteria for rigorous stroke epidemiological studies.

Results: Of 568 stroke patients ascertained in the first year, 31.2% (177/568) were associated with AF (90.4%, i.e. 160/177 ischaemic infarcts). The crude incidence rate of all AF-associated stroke was 60/100,000 person-years (95% CI = 52-70). Prior stroke was almost twice as common in AF compared to non-AF groups (21.9 vs. 12.8%, p = 0.01). The frequency of AF progressively increased across ischaemic stroke patients stratified by increasing stroke severity (NIHSS 0-4, 29.7%; 5-9, 38.1%; 10-14, 43.8%; >or=15, 53.3%, p < 0.0001). The 90-day trajectory of recovery of AF-associated stroke was identical to that of non-AF stroke, but Rankin scores in AF stroke remained higher at 7, 28 and 90 days (p < 0.001 for all).

Discussion: AF-associated stroke occurred in one third of all patients and was associated with a distinct profile of recurrent, severe and disabling stroke. Targeted strategies to increase anticoagulation rates may provide a substantial benefit to prevent severe disabling stroke at a population level.

Fig. 1

Crude incidence rate of all AF-associated stroke stratified by age, with comparison to rate for first-ever stroke. All stroke = First-ever and prior stroke (ischaemic and haemorrhagic); FES = first-ever stroke (ischaemic and haemorrhagic). Crude incidence rate calculated per 1,000 person-years.

Fig. 2

Proportion of ischaemic stroke associated with AF, stratified by stroke severity (NIHSS), showing within-group comparison to first-ever stroke. FES + PS = First-ever stroke and prior stroke, n = 397 (p < 0.0001 for trend); FES = first-ever stroke only, n = 333 (p < 0.001 for trend).

Fig. 3

Trajectories of functional recovery of AF-associated and non-AF stroke based on serial MRS score measurements. First-ever ischaemic stroke, excluding patients where AF status is unknown – i.e. no cardiac monitoring performed. ∗ p < 0.001.