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New-onset seizures are more common in atrial fibrillation, possibly linked by silent strokes, an observational study suggested.
The risk of new-onset seizures was 2.19- to 2.30-fold higher across analyses with atrial fibrillation than without it (P<0.0001), Chien-Yi Hsu, MD, of Taipei Veterans General Hospital in Taipei, Taiwan, and colleagues found.
The incidence was 4.17 per 1,000 person-years with the arrhythmia compared with 1.90 per 1,000 person-years without it, the researchers reported at the European Society of Cardiology in London.
Seizure incidence was predicted by higher CHADS2 stroke risk prediction score, with hazard ratios rising from 1.558-fold with a score of 1 to 4.470 with a score of 4 or greater (P<0.0001 for trend), both as compared with score-0 patients.
After adjustment for gender and comorbidities outside the risk score, the test remained significantly associated with seizure.
"CHADS2 score is a useful scheme for predicting the risk of seizure occurrence in patients with atrial fibrillation," Hsu told attendees.
Possible mechanisms other than silent cerebral infarctions could include reduced global brain perfusion from atrial fibrillation or increased systemic inflammation with afib, although an indirect relationship through shared clinical risk factors is possible too, Hsu noted.
Atrial fibrillation secondary to seizures had been described in case reports before, presumed through increased sympathetic tone and catecholamines, but no prior studies had looked for a relationship in the other direction, Hsu noted.
Out of a random sample of 1 million adults in Taiwan's National Health Insurance Research Database, Hsu's group studied 5,776 people enrolled on the day of diagnosis with atrial fibrillation and the same number of controls were matched by age and sex. None had a history of seizures. They were followed for new-onset seizures from 2000 through December 2011.
As the first longitudinal study to look for seizures in atrial fibrillation, further confirmation of a link and looking for causality would be necessary.
Other limitations were the retrospective nature of the analysis, precluding determination of causal associations, and use of administrative claims data, whereas Hsu noted that analysis of only seizures confirmed by neurologist or EEG would be more precise.
From the American Heart Association:
Disclosures
Hsu disclosed having no relevant relationships with industry.
Primary Source
European Society of Cardiology
Hsu C-Y, et al "Association between atrial fibrillation and risk of seizure: usefulness of CHADS2 score for risk stratification" ESC 2015.