Stroke may trigger atrial fibrillation within 1 year, study finds

A large cohort study has found that the risk of being newly diagnosed with atrial fibrillation within a year of a stroke, such as a cerebral infarction or cerebral hemorrhage, may be significantly increased.

While atrial fibrillation, a common arrhythmia, is known to cause stroke, this study confirms that the reverse may also be true, warranting special attention.

Samsung Medical Center said Thursday that a team of researchers confirmed this after tracking changes in atrial fibrillation risk among stroke survivors.

The research team was led by Professor Shin Dong-wook of the hospital's Department of Family Medicine, Professor Han Kyung-do of the Department of Statistics and Actuarial Science at Soongsil University, Professor Kang Ji-hun of the Department of Family Medicine at Kosin University Gospel Hospital, and Professor Yoo Jeong-eun of the Department of Family Medicine at Seoul National University Hospital Gangnam Center.

Based on data from the National Health Insurance Service (NHIS), the team analyzed 98,706 patients with cerebral infarction and 47,695 patients with cerebral hemorrhage who had a history of medical examinations from 2010 to 2018 and compared them with general population controls.

The control group was matched 1:1 with the patients not only by age and gender but also by income level, region of residence, smoking, alcohol consumption, exercise, BMI, and underlying medical conditions to exclude the possibility that other factors may have contributed to the development of atrial fibrillation.

The researchers calculated that patients with a stroke had a 2.32-fold increased risk of developing atrial fibrillation over the entire follow-up period, rising to a 7.32-fold risk in the first year after diagnosis and remaining at a 1.64-fold risk a year later.

A similar trend was found for cerebral hemorrhage. The risk of atrial fibrillation was 1.24 times higher in patients with cerebral hemorrhage, rising to four times within a year of the event, according to the researchers' earlier paper in the journal Circulation. After a year, the risk level became similar to that of controls.

The researchers explain these findings by suggesting that after a stroke, an imbalance in the autonomic nervous system or a systemic inflammatory response can lead to electrophysiologic instability in the heart, which can increase the risk of atrial fibrillation. In particular, they said that overactivation of the sympathetic nervous system and increased inflammatory cytokines can lead to structural and functional changes in the atria that increase the likelihood of atrial fibrillation.

However, they added, the possibility that previously undetected atrial fibrillation may have been diagnosed should also be considered, as the period immediately following a stroke diagnosis is a time of intensive hospitalization, outpatient visits, and electrocardiograms.

“Atrial fibrillation is known to be an important cause of stroke, but conversely, it is not uncommon for atrial fibrillation to be diagnosed after a stroke,” Professor Shin said. "Especially in the first year after a stroke, the incidence of atrial fibrillation is concentrated, so early diagnosis and active management are necessary. Integrated prevention and management of the common risk factors for both stroke and atrial fibrillation can reduce recurrence and complications."