Even after adjusting for atrial fibrillation (AF) risk factors, exposure to secondhand smoke in childhood increases adult AF risk, although part of this relationship is that children of parents who smoke will more likely smoke themselves, according to study results published in Journal of the American College of Cardiology.

Several large epidemiological studies have linked cigarette smoking to incident AF, limited data exists regarding the effects of secondhand smoke on AF. One previous study did link secondhand smoke exposure in childhood or in utero to increased AF risk, but it relied on self-reported exposure and may have been affected by recall bias. For the current study, researchers investigated the hypothesis that parental smoking predicts AF among offspring by analyzing data on offspring cohort participants who had known smoking parents in the original cohort of the multigenerational Framingham Heart Study.

Among 5124 offspring participants in the Framingham Heart Study, 55% (N=2816) had parental smoking data available for childhood up to 18 years, and 82% of these offspring participants experienced secondhand smoke exposure. Participants exposed to smoking in childhood were more likely to smoke themselves, have hypertension, and have a family history of AF. Over a median follow-up of 40.5 (interquartile range, 33.3-41.9) years, 14.3% (n=404) of eligible offspring participants developed AF, for an overall incidence rate of 4.02/1000 person-years. After multivariable adjustment, researchers observed an 18% increase in incidence of AF for every pack/day increase in parental smoking.

After adjusting for body mass index, age, sex, diabetes, coronary heart disease, alcohol consumption, hypertension, and family history of AF, researchers found a significant association between parental smoking and increased odds for offspring smoking (adjusted odds ratio 1.34; 95% CI, 1.17-1.54; P <.001).

After adjusting for those same covariates, offspring participant smoking was associated with a 32% increase in incident AF (adjusted hazard ratio, 1.32; 95% CI, 1.11-1.56; P =.002).

After adjusting for offspring smoking, researchers found that 17% (95% CI, 1.5%-103.3%) of the relationship between parental smoking and AF among offspring was mediated by offspring smoking.

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Study limitations included incomplete data on parental smoking habits, variations in parental smoking habits, and the potential for clinically silent AF; however, the researchers concluded that these findings should encourage current smokers to quit and discourage potential smokers from picking up the habit.

The researchers also said, “Future studies should investigate the biological mechanisms responsible for atrial substrate modification resulting from smoke exposure in utero and during childhood development.”

One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Groh CA, Vittinghoff E, Benjamin EJ, Dupuis J, Marcus GM. Childhood tobacco smoke exposure and risk of atrial fibrillation in adulthood. J Am Coll Cardiol. 2019;74:1658-1664.