Secondhand tobacco smoke and risk of atrial fibrillation: an observational epidemiologic and gene-environment interaction analysis

Second-hand tobacco smoke (SHS) is related to coronary artery disease and increases susceptibility to arrhythmia inducibility including atrial fibrillation (AF). However, epidemiologic evidence on the relationship between SHS and the risk of incident AF remains controversial.

To evaluate the effect of SHS exposure on the long-term risk of AF and assess whether gene-environment interaction (synergism) exists by utilising the population-based data from the UK biobank.

We performed a nationwide population-based cohort study using the UK Biobank database. Participants with previous AF or current smokers were excluded. Participants were categorised into SHS-exposure and non-exposure groups. The risk of incident AF was assessed using the multivariable Cox proportional hazards model. We also evaluated the synergistic effect of SHS exposure and the polygenic risk score (PRS) of AF.

Out of 400,493 participants, AF occurred in 23,471 (5.9%) during a median follow-up of 12.5 years. The SHS-exposure group (mean exposure 2.2 ± 5.2 hours/week) had a higher proportion of male participants with a younger age. The risk of incident AF was significantly increased in the SHS-exposure group (multivariable-adjusted hazard ratio [aHR] 1.06, 95% confidence interval 1.03-1.10, P <0.001) compared to the non-exposure group, suggesting a dose-dependent manner (aHR of severe SHS-exposure group, 1.11 [1.03-1.20], P = 0.005). The risk of AF increases regardless of the exposure location (home, outside, or workplace). When SHS-exposure was combined with the high genetic risk of AF, significant additive interaction was observed on the risk AF (Synergy Index of SHS-exposure with 3rdtertile of AF PRS, 1.13 [1.02-1.25], P = 0.024).

Exposure to SHS is a significant predictor for an increased risk of AF, with a synergistic effect when combined with genetic predisposition. Minimising SHS exposure, especially in individuals with a heightened genetic susceptibility to AF, may hold potential benefits for reducing the future risk of AF.