Impact of Smoking Cessation Upon Diagnosis of Atrial Fibrillation

Soryoung Lee, PhD

Results of a new analysis presented at the European Society of Cardiology (ESC) Congress 2020 are detailing the impact smoking cessation can have on stroke risk among patients with atrial fibrillation.

Data from the analysis outlines the impact cutting smoking can have in this particular patient population—noting those who quit smoking reduced their risk of stroke by 30% and risk of mortality by 16% compared to their counterparts who continued to smoke.

“Smoking precipitates blood clots that could lead to a stroke, which may be why giving up lowers risk. The remaining stroke risk after quitting might be through the damage already caused to the arteries,” said Soryoung Lee, PhD, of the Seoul National University Hospital, in a statement.

With atrial fibrillation already the most common arrhythmia and expected to grow in prevalence over the coming decades, Lee and a team of colleagues from the Catholic University of Seoul and the Liverpool Heart and Chest Hospital designed the current study to assess the impact of smoking and smoking cessation on stroke risk among patients with new-onset atrial fibrillation. To identify patients for inclusion in their study, investigators performed a query of the Korean National Health Insurance Service database and the National Health Screening database.

From this, investigators identified a cohort of 523,174 patients with newly diagnosed atrial fibrillation between 2010-2016. For inclusion in the study, patients needed to be at least 18 years of age and receive a checkup exam within 2 years before and after the initial atrial fibrillation diagnosis. After the application of inclusion criteria, investigators were left with a group of 97,869 patients for their statistical analysis. The mean age of this population was 61±12 years, 62% were men, the group had a mean CHA2DS2-VASc score of 2.3±1.5, and the median follow-up period was 3 years.

Patients included in the study were stratified into 4 groups based on their smoking status before and after their atrial fibrillation diagnosis. These groups were defined as never smokers, new smokers after diagnosis, those who quit smoking after diagnosis, and persistent smokers. Of note, 79% of participants were never smokers, 1% were new smokers, 7% were classified as having quit smoking, and 12% were persistent smokers. For the purpose of analysis, incident stroke was chosen as the primary outcome of the study.

During the follow-up period, incident stroke occurred in 3121 patients and 4882 deaths were recorded among the study—resulting in event rates of 10 per 1000 person-years and 15.4 per 1000 person-years, respectively. In multivariable-adjusted analyses, new and persistent smokers were at an increased risk of stroke compared to never smokers. Additionally, those who quit smoking after the diagnosis of atrial fibrillation also showed a higher risk of stroke than never smokers (HR, 1.19; 95% CI, 1.03-1.38), but a lower risk compared to those who continued smoking after diagnosis (HR, 0.720; 95% CI, 0.608-0.851).

Additionally, results of the analysis indicated patients considered heavy smokers, which was defined as smoking 20 cigarettes a day for 30 years or more, were less likely to experience the same level of reduction in risk from quitting as their counterparts who were not considered heavy smokers at the time of their diagnosis.

“This may be related to longer-term damage to the blood vessels which increases susceptibility to having a stroke,” added Lee, in the aforementioned statement. “If you don’t smoke, don’t start. If you do, it’s never too late to quit. Regardless of how much you smoke, kicking the habit is good for health.”

This study, “Impact of smoking cessation after the new diagnosis of atrial fibrillation on the risk of stroke: a nationwide cohort study,” was presented as part of ESC 2020.