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Occurrence of hemispheric and retinal ischemia in atrial fibrillation compared with carotid stenosis
D C Anderson1, L J Kappelle, M Eliasziw
1Hennepin County Medical Center and University of Minnesota, Minneapolis 55415, USA. ander012@tc.umn.edu
Insights
Retinal ischemia is more frequently linked to carotid atherosclerosis than atrial fibrillation. Initial symptom location strongly predicts future events in carotid stenosis patients, regardless of new symptoms
Area of Science:
- Neurology
- Vascular Medicine
- Ophthalmology
Background:
- Retinal ischemia can stem from carotid atherosclerosis or atrial fibrillation.
- Carotid stenosis severity may influence the likelihood of retinal versus hemispheric events.
Purpose of the Study:
- To compare the frequency of retinal ischemia caused by carotid atherosclerosis versus atrial fibrillation.
- To assess if worsening carotid stenosis increases retinal event risk compared to hemispheric events.
Main Methods:
- Utilized data from Stroke Prevention in Atrial Fibrillation (SPAF) I-III and North American Symptomatic Carotid Endarterectomy Trial (NASCET).
- Calculated hemispheric:retinal (H:R) odds for ischemic events in patients with atrial fibrillation and 50%-99% carotid stenosis.
Main Results:
- The H:R odds were 25:1 in SPAF patients and 2:1 in NASCET patients.
- In NASCET, retinal symptoms predicted recurrent events (1:4 H:R odds) more than hemispheric symptoms (6:1 H:R odds).
- Increasing carotid stenosis (50%-99%) did not affect H:R odds.
Conclusions:
- Retinal symptoms are more characteristic of carotid stenosis than atrial fibrillation.
- Initial symptom location in carotid stenosis predicts subsequent event location, even contralaterally.
- Hemodynamic effects are not more critical than hemispheric effects in carotid stenosis-related retinal events.
Background And Purpose:
The goal of this study was to examine the hypotheses that retinal ischemia is caused more often by carotid atherosclerosis than by atrial fibrillation and that the odds of retinal events compared with hemispheric events increase with worsening carotid stenosis.
Methods:
We used data from the Stroke Prevention in Atrial Fibrillation (SPAF) I through III trials and North American Symptomatic Carotid Endarterectomy Trial (NASCET), calculating hemispheric:retinal (H:R) odds for the territory of ischemic events during follow-up in patients with atrial fibrillation and medically treated 50% to 99% carotid stenosis or occlusion in the respective trials.
Results:
The H:R odds were 25:1 in the SPAF aspirin-assigned patients and 2:1 for NASCET vessels. In NASCET patients, the H:R odds of recurrent ischemic events were 1:4 for vessels randomized initially for retinal symptoms compared with 6:1 for those randomized for hemispheric events (significant difference; P<0.001). Moreover, the H:R odds of first events in the territory of the contralateral asymptomatic artery were 1:1 if the randomized vessel had retinal symptoms compared with 4:1 if the randomized vessel had hemispheric symptoms (significant difference; P<0.01). Increasing carotid stenosis in the 50% to 99% range had no effect on H:R odds (P=0.8).
Conclusions:
These findings confirm that retinal symptoms are more typical of carotid stenosis. Hemodynamic effects do not appear to be more important in the pathogenesis of retinal events than hemispheric ones in carotid stenosis. The retinal versus hemispheric location of initial symptoms is strongly predictive of the location of subsequent events in patients with carotid stenosis, even when new symptoms are contralateral to the original ones.