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Assessment of three schemes for stratifying stroke risk in patients with nonvalvular atrial fibrillation
L A Pearce1, R G Hart, J L Halperin
1Axio Research Corporation, Seattle, Washington, USA.
Insights
Three risk stratification schemes effectively identified low-risk patients with atrial fibrillation on aspirin therapy. However, these methods were less consistent in identifying high-risk individuals for ischemic stroke prevention.
Area of Science:
- Cardiology
- Neurology
- Clinical Trials
Background:
- Nonvalvular atrial fibrillation (AF) poses variable ischemic stroke risks.
- Prophylactic antithrombotic therapy choice depends on individual risk.
- Prior cerebral ischemia influences stroke risk stratification in AF patients.
Purpose of the Study:
- To assess three stroke risk stratification schemes in nonvalvular AF patients treated with aspirin.
- To evaluate the ability of these schemes to identify high, low, and intermediate stroke risk categories.
- To compare the performance of risk stratification schemes in a cohort without prior cerebral ischemia.
Main Methods:
- Applied criteria from three risk stratification schemes to a cohort of AF patients.
- Analyzed a longitudinally observed cohort from a multicenter clinical trial.
- Assessed scheme performance in identifying patients with annual ischemic stroke risks of ≥6% (high), ≤2% (low), and intermediate.
Main Results:
- A total of 48 ischemic strokes occurred in 1,073 AF patients on aspirin over a mean 1.8-year follow-up (rate = 2.5/100 person-years).
- All three schemes successfully identified low-risk patients (observed rates 0.3-1.1/100 person-years), though the proportion varied (14%-45%).
- Observed high-risk stroke rates ranged from 3.5-7.2/100 person-years; two schemes classified all patients >75 years as high risk, while one identified a low-risk subgroup within this age bracket.
Conclusions:
- Available risk stratification schemes effectively identified low-risk AF patients on aspirin therapy.
- The consistency of identifying high-risk patients varied among the assessed schemes.
- Further refinement may be needed for accurate high-risk patient identification in AF.
Purpose:
The risk of ischemic stroke varies widely among patients with nonvalvular atrial fibrillation, influencing the choice of prophylactic antithrombotic therapy. We assessed three schemes for stroke risk stratification in these patients who were treated with aspirin and who did not have prior cerebral ischemia.
Subjects And Methods:
Criteria from three schemes of risk stratification were applied to a longitudinally observed cohort of patients with atrial fibrillation who did not have prior cerebral ischemia and who were treated with aspirin alone or aspirin combined with low, ineffective doses of warfarin in a multicenter clinical trial. The ability of the schemes to identify patients at high (>/=6%), low (
Results:
During a mean follow-up of 1.8 years, 48 ischemic strokes occurred among 1,073 patients with atrial fibrillation who were taking aspirin (rate = 2.5 per 100 person-years). Each of the three schemes predicted stroke and disabling stroke, and successfully identified patients at low risk (observed stroke rates of 0.3 to 1.1 per 100 person-years), although the fractions of the cohort that were categorized as low risk varied from 14% to 45%. The observed rates of ischemic stroke among patients categorized as high risk ranged from 3.5 to 7.2 per 100 person-years among the stratification schemes. Two schemes considered all patients >75 years old as high risk (observed stroke rate 4.2 per 100 person-years), while the remaining scheme classified one third of patients in this age group as low risk (observed stroke rate 0.6 per 100 person-years).
Conclusions:
When tested in a large cohort of patients with atrial fibrillation who were treated with aspirin, available risk-stratification schemes successfully identified patients with low rates of ischemic stroke, but less consistently identified high-risk patients.
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