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Prognosis

Ischemic stroke with accompanying atrial fibrillation was associated with reduced survival and functional status

ACP J Club. 1997 Mar-Apr;126:47. doi:10.7326/ACPJC-1997-126-2-047


Source Citation

Lin HJ, Wolf PA, Kelly-Hayes M, et al. Stroke severity in atrial fibrillation. The Framingham Study. Stroke. 1996 Oct;27:1760-4.


Abstract

Objective

To determine whether ischemic stroke severity and mortality are greater in patients who also have atrial fibrillation.

Design

Inception cohort followed for 30 days to 1 year after ischemic stroke.

Setting

Framingham, Massachusetts, USA.

Patients

5070 men and women between 30 and 64 years of age who were free of cardiovascular disease, including stroke, at study entry. During > 40 years of follow-up, 508 patients (57% women) had an initial ischemic stroke, and 104 (20%) of these patients had accompanying atrial fibrillation.

Assessment of prognostic factors

At each biennial appointment, physical examinations and laboratory tests, including 12-lead electrocardiography (ECG), were done, and risk factors for cardiovascular diseases were evaluated. Atrial fibrillation was identified at the biennial evaluation or during interim hospitalizations or outside examinations. Onset of atrial fibrillation was defined as the time of the first documentation on ECG.

Main outcome measures

Stroke severity (rated as none, mild, moderate, severe, or fatal), 30-day and 1-year mortality, stroke recurrence, and functional status indicated by the Barthel index (100-point range).

Main results

Stroke severity was more likely to be severe or fatal in patients with atrial fibrillation than in those without atrial fibrillation (39% vs 28%, P = 0.048). 30-day mortality was greater in patients who had a stroke and atrial fibrillation than in those who had a stroke but no atrial fibrillation (25% vs 14%). In multivariate analysis adjusting for age, coronary heart disease, and cigarette smoking, the odds ratio for 30-day mortality in patients with stroke and atrial fibrillation was 1.84 (95% CI 1.04 to 3.27, P = 0.036). Follow-up beyond 30 days after the initial stroke was available for 150 patients, including 30 with associated atrial fibrillation. By 1 year follow-up, 63% of the patients with atrial fibrillation had died and 23% had a stroke recurrence compared with 34% and 8%, respectively, of those without atrial fibrillation (P < 0.001 for both comparisons). Patients with atrial fibrillation also had worse mean scores on the Barthel index than did those without atrial fibrillation (46 vs 79, P = 0.003, at 6 mo after stroke).

Conclusion

Patients who had an ischemic stroke with accompanying atrial fibrillation had higher mortality, graver stroke severity, more recurrences, and poorer functional status than those without atrial fibrillation.

Source of funding: National Institutes of Health.

For article reprint: Dr. P.A. Wolf, Department of Neurology, Boston University School of Medicine, 80 East Concord Street, B-608, Boston, MA 02118, USA.


Commentary

The Framingham Study was the first methodologically sound trial to show that atrial fibrillation is a major risk factor for stroke (1). The risk for stroke was shown to be 5% annually in patients with chronic atrial fibrillation. This risk is considerably higher soon after the onset of atrial fibrillation (2). The report by Lin and colleagues extends the findings of earlier reports and shows the high risk for disabling or fatal strokes and stroke recurrence in patients with atrial fibrillation.

A pooled analysis of 5 primary prevention trials of anticoagulation in atrial fibrillation showed that anticoagulation reduced the annual risk for stroke from 4.5% to 1.5%, a relative risk reduction of 68% (3). The risk for bleeding was minimally increased in patients who received anti-coagulation to an international normalized ratio (INR) of 2 to 3. In a secondary prevention trial, the annual risk for recurrent stroke in patients with atrial fibrillation and transient ischemic attacks or minor stroke was reduced from 12% to 4%, a relative risk reduction of 66% (4).

Because strokes in patients with atrial fibrillation are more likely to be severely disabling or lethal, prevention with warfarin anticoagulation should be strongly encouraged. Recent data showed that only 32% of all patients with atrial fibrillation and only 19% of patients > 80 years of age (who are at the greatest risk for stroke) received warfarin anticoagulation in 1992 and 1993 (5).

Based on current knowledge, it is strongly recommended that long-term warfarin therapy (INR 2 to 3) be given to all patients > 65 years of age who can be safely anticoagulated. Warfarin should also be given to patients < 65 years if they have had previous transient ischemic attacks or strokes or if they have hypertension, diabetes, or other cardiovascular disease.

James Kitchens, MD
St. Michael's HospitalToronto, Ontario, Canada


References

1. Wolf PA, Dawber TR, Thomas HE Jr, Kannel WB. Neurology. 1978;28:973-7.

2. Wolf PA, Kannel WB, McGee DL, et al. Stroke. 1983;14:664-7.

3. Atrial Fibrillation Investigators. Arch Intern Med. 1994;154;1449-57.

4. European Atrial Fibrillation Trial Study Group. Lancet. 1993;342:1255-62.

5. Stafford RS, Singer DE. Arch Intern Med. 1996;156:2537-41.