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Risk of stroke in non-rheumatic atrial fibrillation
Insights
Men with non-rheumatic atrial fibrillation face a significantly higher stroke risk, confirmed by the Whitehall Study. However, absolute stroke rates were lower than in the Framingham study, impacting preventive trial planning.
Area of Science:
- Cardiology
- Neurology
- Epidemiology
Background:
- Non-rheumatic atrial fibrillation is a known risk factor for stroke.
- Previous studies, like the Framingham study, have estimated this increased risk.
Purpose of the Study:
- To estimate the risk of stroke in men with non-rheumatic atrial fibrillation using two large UK cohort studies.
- To compare these estimates with existing data and consider implications for preventive strategies.
Main Methods:
- Analysis of data from the Whitehall Study of London Civil Servants.
- Analysis of data from the British Regional Heart Study.
- Calculation of relative and absolute stroke risk estimates.
Main Results:
- The Whitehall Study estimated a relative stroke risk of 6.9 in men with atrial fibrillation, confirming previous findings.
- The British Regional Heart Study yielded a non-significant risk estimate due to low event numbers.
- Absolute stroke rates in both cohorts were lower than those reported in the Framingham study.
Conclusions:
- Non-rheumatic atrial fibrillation significantly increases stroke risk in men.
- Lower absolute stroke rates in these cohorts suggest a potentially smaller benefit from preventive measures compared to other populations.
- These findings have implications for the design and interpretation of clinical trials for stroke prevention.
Abstract:
Estimates of the risk of stroke for men with non-rheumatic atrial fibrillation were obtained from two large cohort studies--the Whitehall Study of London Civil Servants and the British Regional Heart Study. The first cohort provided an estimated relative risk of stroke of 6.9 compared with controls. This increased risk confirms that of the other prospective estimate, 5.6, found in the Framingham study. In the second cohort only one of the men at risk had a stroke, and the risk estimate did not differ significantly from unity. The absolute rates of stroke in both cohorts were lower than those reported in the Framingham study, implying a lesser potential benefit from preventive measures. These lower rates should be considered in the planning of trials. The risk of stroke was significantly associated with raised systolic or diastolic blood pressure but not with age or coronary heart disease.