Association between secondhand smoke exposure and incident heart failure: The Multi-Ethnic Study of Atherosclerosis (MESA).

Aims: There are no studies on the association between secondhand smoke (SHS) exposure and incident heart failure (HF). This cohort study aimed to examine the associations of self-reported and urinary cotinine-assessed SHS exposure with incident HF.

Methods And Results: This study included 5548 non-active smoking participants aged 45-84 years and free of known cardiovascular diseases and HF at baseline who self-reported SHS exposure time in the Multi-Ethnic Study of Atherosclerosis (MESA) at baseline (2000-2002). A cohort subset of 3376 non-active smoking participants underwent urinary cotinine measurements. HF events were verified by medical records or death certificates and ascertained from baseline through 2019. Multivariable Cox proportional hazards regression analysis was used with adjustment for demographic variables, traditional cardiovascular risk factors, physical activity, tobacco pack-years and medications. During a median follow-up of 17.7 years, 353 and 196 HF events were identified in the self-report cohort and cohort subset, respectively. In the self-report cohort, compared with the SHS unexposed group (0 h/week), the highest tertile of the SHS exposed group (7-168 h/week) was not associated with incident HF (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.49-1.00; p = 0.052). In contrast, in the cohort subset, participants with detectable urinary cotinine >7.07 ng/ml had a higher risk of incident HF than those with undetectable urinary cotinine ≤7.07 ng/ml (HR 1.45, 95% CI 1.03-2.06; p = 0.034). There were no significant heterogeneities in HF risk by age, sex, race/ethnicity, or past smoking status.

Conclusion: Secondhand smoke exposure reflected by modestly increased urinary cotinine (>7.07 ng/ml) rather than self-report in non-active smokers was associated with a 40-50% higher risk of any HF event.