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Duration of atrial fibrillation and imminence of stroke: the Framingham study
Insights
Atrial Fibrillation (AF) significantly increases stroke risk five-fold, independent of other heart conditions. Strokes associated with AF are imminent, with a notable clustering at onset.
Area of Science:
- Cardiology
- Neurology
- Epidemiology
Background:
- Atrial Fibrillation (AF) is a common arrhythmia.
- The association between AF and stroke is well-established but requires further quantification.
- Understanding AF's role as a stroke precursor is crucial for preventative strategies.
Purpose of the Study:
- To examine the role of Atrial Fibrillation (AF) as a precursor of stroke.
- To quantify the independent risk of stroke conferred by AF.
- To assess the timing and recurrence patterns of stroke in patients with AF.
Main Methods:
- Analysis of the Framingham Heart Study cohort.
- 30-year follow-up period.
- Identification of stroke events in relation to AF onset, excluding rheumatic heart disease.
Main Results:
- AF increased stroke risk five-fold, independent of cardiac failure and coronary heart disease.
- Stroke events showed distinct clustering at the time of AF onset.
- Thirty-day case-fatality rates were similar for strokes with and without AF (17% vs. 19%).
- Stroke recurrence within 6 months was more than twice as common in the AF group (47% vs. 20%).
Conclusions:
- Atrial Fibrillation is a substantial and imminent precursor to stroke.
- AF's contribution to stroke risk is comparable to other major cardiovascular risk factors.
- While short-term fatality is similar, AF increases the likelihood of early stroke recurrence.
Abstract:
The role of Atrial Fibrillation (AF) as a precursor of stroke was examined in the Framingham cohort based on 30 years of follow-up during which time 501 strokes occurred. There were 59 persons who sustained stroke in association with AF excluding those with rheumatic heart disease. AF increased the risk of stroke five-fold and the excess risk was found to be independent of the frequently associated cardiac failure and coronary heart disease. The contribution of AF to stroke risk was also at least as powerful as that of the other cardiovascular precursors. Stroke associated with AF was not only independent and substantial but also imminent. There was a distinct clustering of stroke events at the time of onset of the AF. Thirty day case-fatality rates were no different in those with strokes accompanied by AF than not at 17% versus 19% respectively. Recurrences in those with AF were only slightly more frequent, 25% versus 20%, a difference that was not statistically significant. Stroke recurrence in the first 6 months following initial stroke was more than twice as common (47% versus 20%) in the AF group.