Second-hand smoke may up risk of AF

Exposure to second-hand tobacco smoke may increase the risk of developing atrial fibrillation (AF), as shown in a population-based cohort study using the UK Biobank database.

The study included 400,493 individuals (mean age 56.5 years, 55.2 percent female). On a questionnaire, 21 percent reported exposure to second-hand smoke (mean 2.2 hours per week). The risk of incident AF was assessed using the multivariable Cox proportional hazards model. The synergistic effect of second-hand smoke exposure and AF’s polygenic risk score (PRS) were also evaluated. [Lee KY, et al. EHRA 2024, moderated poster session1]

During a median follow-up of 12.5 years, AF occurred in 23,471 (5.9 percent) individuals. After adjustment for potential confounders such as age, sex, ethnicity, BMI, daily alcohol intake, physical activity, diabetes, high blood pressure, high blood lipids, socioeconomic status, and enrolment centre, the risk of incident AF was significantly higher among those who had reported second-hand smoke exposure than those who had not (adjusted hazard ratio [aHR], 1.06; 95 percent confidence interval [CI], 1.03–1.10; p<0.001).

The increased risk of AF was consistent regardless of whether the exposure occurred at home (aHR, 1.10; 95 percent CI, 1.03–1.17) or outdoors (aHR, 1.06; 95 percent CI, 1.02–1.09), indicating that exposure universally elevates the risk of AF.

The risk was higher with longer hours of exposure to tobacco smoke. For instance, those exposed to second-hand smoke for an average of 7.7 hours per week had an 11 percent greater risk of developing arrhythmia than their unexposed peers (aHR 1.11; 95 percent CI 1.03–1.20).

Interestingly, individuals with the highest genetic susceptibility to AF based on a polygenic risk score had a higher risk of incident AF related to second-hand smoke exposure.

Public health implication

AF is one of the most common types of arrhythmias. “Minimizing second-hand smoke exposure in those with a heightened genetic susceptibility to AF may hold potential benefits for reducing the risk of AF,” said study author Dr Kyung-Yeon Lee from Seoul National University Hospital in Korea, who presented the results at EHRA 2024.  

“Our finding that passive smoking is harmful, not only in enclosed indoor spaces but also outdoor environments, underscores the importance of smoking bans and smoking cessation programmes to protect public health,” she added. “We should all try to avoid spending time in smoky environments.”

Dr Juhani Junttila (Medical Research Center Oulu in Finland), co-chair of the moderated poster session where Lee presented, couldn’t agree more. “Smoking is bad for health, so is second-hand smoke … and that is something we need to keep in mind.”

He added that the findings also highlight the importance of population-based studies.