Clinical study
Atrial fibrillation as a risk factor for stroke recurrence

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Abstract

Background

Although atrial fibrillation is a well-known risk factor for ischemic stroke, the extent to which it increases the risk of stroke recurrence, particularly in elderly patients, is less certain.

Methods

We performed a retrospective cohort study of 915 patients aged 50 to 94 years who were admitted with an ischemic stroke. The rates of recurrent strokes and recurrent severe strokes were estimated with the Kaplan-Meier method. The effects of atrial fibrillation on stroke risk were analyzed with proportional hazards models.

Results

Of the 829 patients who survived the initial hospitalization, 163 (20%) had a stroke during follow-up. Of the 203 patients with atrial fibrillation during index hospitalization who were not anticoagulated, 54 (27%) had recurrent strokes, compared with 18% (19/103) among those with atrial fibrillation who were anticoagulated and 17% (90/523) among those without atrial fibrillation. The age-adjusted hazard ratio for recurrent stroke among those with atrial fibrillation who were not treated with anticoagulants was 2.1 (95% confidence interval [CI]: 1.4 to 2.9; P <0.001), whereas the hazard ratio for recurrent severe stroke was 2.4 (95% CI: 1.6 to 3.6; P <0.001). The increased risk was observed even in patients aged ≥80 years and persisted during the follow-up for more than 5 years.

Conclusion

Atrial fibrillation was an independent risk factor for stroke recurrence over a wide age range.

Section snippets

Design and sample

We performed a retrospective cohort study of stroke patients admitted to the University Hospital Marqués de Valdecilla, a 1000-bed teaching facility serving a population of 500,000 in the region of Cantabria, in northern Spain. We identified all patients admitted with acute cerebrovascular disease from January 1, 1992, through December 31, 1994, by searching the hospital’s computerized database. Patients were included in the study if the following criteria were fulfilled: rapidly developing

Results

Of the 915 patients who met inclusion criteria, 86 (9%) had a fatal index stroke. Of the 829 surviving patients in the final study cohort (Table 1 ), 163 (20%) had a recurrent stroke (including 47 [6%] with fatal strokes), 63 (8%) died of cardiovascular diseases other than stroke, 102 (12%) died of noncardiovascular causes, and 47 (6%) died of unknown causes. The median follow-up of the whole cohort was 2.9 years (range, 0 to 8.6 years). Three hundred and six (37%) of the 829 patients had

Stroke recurrence in patients with atrial fibrillation who were not anticoagulated

Among the 203 patients with atrial fibrillation who were not anticoagulated, 54 (27%) had a recurrent stroke during follow-up, compared with 17% (90/523) of those in normal sinus rhythm (P <0.0001; Figure 1 )

In comparison with patients in sinus rhythm, patients with atrial fibrillation during the index hospitalization had an increased risk of stroke recurrence, particularly for severe strokes, when stratified by age (Figure 2 ; Table 2 ). The recurrence rate appeared to be higher during the

Multivariate analysis

Advanced age and atrial fibrillation in the absence of anticoagulation were the only factors that were independently associated with stroke recurrence. In comparison with younger patients, those aged 70 years or more had a 1.5-fold greater risk of stroke recurrence (95% confidence interval [CI]: 1.0 to 2.2; P = 0.04) and a 2.1-fold greater risk of recurrent severe stroke (95% CI: 1.3 to 3.5; P = 0.002).

Patients with atrial fibrillation had a 2.1-fold increased risk of recurrent stroke (95% CI:

Stroke recurrence in patients with atrial fibrillation who were anticoagulated

Among the 103 patients with atrial fibrillation who survived the index stroke and who received anticoagulation, 19 (18%) had a new stroke during follow-up (compared with 27% of nonanticoagulated patients with atrial fibrillation). Patients with atrial fibrillation who were given anticoagulants were younger (mean [± SD] age, 71 ± 6 years vs. 78 ± 7 years, P <0.001), had a higher frequency of heart failure (40% [41/103] vs. 22% [44/203], P = 0.001), and had fewer disabling strokes (36% [37/103]

Discussion

The effect of atrial fibrillation on stroke recurrence has been uncertain. In a cross-sectional study, atrial fibrillation was more frequent in patients admitted with recurrent strokes than in patients with a first stroke (24% vs. 16%); long-term follow-up was not provided (7). Lai et al. followed 621 patients with ischemic stroke for an average of 24 months and found that atrial fibrillation was associated with stroke recurrence (6). However, others have reported negative results. In a cohort

Acknowledgements

We acknowledge the dedication of the physicians and staff who cared for the patients, particularly those in the Services of Internal Medicine and Neurology, and the administrative collaboration of the Servicios de Admisión from the Hospitals Marqués de Valdecilla and Sierrallana.

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This study was supported by a research grant from the Fundación Pública Marqués de Valdecilla, Santander, Spain.

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