A first-of-its-kind study indicates that gestational and early life secondhand smoke (SHS) exposure may double one’s chance of developing atrial fibrillation (AF) as an adult. The study by UC San Francisco researchers was published in the online version of HeartRhythm, the official journal of the Heart Rhythm Society (HRS). The study is being published in tandem with Atrial Fibrillation Awareness Month this September to help further inform the public about AF and potential risk factors.
AF is the most common heart arrhythmia and affects more than 2.7 million American adults. An aging population and advancements in cardiovascular treatment suggest that the incidence and prevalence of AF will continue to increase with significant personal and societal implications[i]. Despite progress in reducing smoking prevalence and the resulting SHS exposure, SHS remains a significant hazard in the United States and worldwide.[ii]
Of the 4,976 participants of the study, 593 (11.9 percent) reported having AF. In unadjusted analyses, participants with AF were more likely to have been exposed to SHS in utero, as a child, as an adult, at home and at work. After adjusting for potential confounding factors, having had a smoking parent during gestational development (p=0.009) and residing with a smoker during childhood (p=0.007) were each significantly associated with AF. Furthermore, both positive associations were more pronounced among patients without risk factors for AF such as older age, hypertension, coronary heart disease and congestive heart failure.
The study includes data from the Health eHeart Study, which is an internet-based, longitudinal, cardiovascular cohort study. The study participants completed baseline SHS exposure and medical conditions questionnaires. SHS exposure was assessed through a validated 22-question survey, and prevalent AF was assessed by a self-report, with validation by review of electronic medical records. Analysis was performed to determine whether the presence or absence of at least one risk factor for AF modified the relationship between SHS and AF.
“Since there are no primary prevention strategies for AF, our discovery of a modifiable risk factor like secondhand smoke is very important,” said Gregory Marcus, MD, MAS, Associate Professor at the UCSF School of Medicine and senior author of the study. “A first step to preventing atrial fibrillation is to become aware of risk factors that affect your heart and might at least theoretically be avoided. Our study further underscores the significance of living a heart-healthy lifestyle and making smarter choices like abstaining from smoking and protecting families from secondhand smoke.”
The study authors note that future research into the effects of SHS is needed to reveal novel mechanisms underlying AF and consequently new therapeutic options. Furthermore, research is needed to detect additional causes of lone AF in order to identify prevention strategies.
The Health eHeart Study seeks to develop strategies to prevent and treat all aspects of heart disease, and encourage a healthy lifestyle, free of heart disease. The study uses technology such as smartphone apps, sensors and other devices to gather data and aims to enroll up to one million participants. Anyone 18 years of age or older with internet access is encouraged to join.