Serum Cotinine and Silent Myocardial Infarction in Individuals Free from Cardiovascular Disease.

Serum cotinine is a sensitive and specific marker of tobacco exposure, including second-hand smoke exposure. We sought to explore the association of tobacco exposure determined by serum cotinine with electrocardiographic silent myocardial infarction (SMI). A total of 7,006 participants (59.0 ± 13.3 years; 52.6% women, 49.7% non-Hispanic whites) without cardiovascular disease from the Third National Health and Nutrition Examination Survey (NHANES III) were included in this analysis. SMI was defined as electrocardiographic evidence of MI in the absence of a history of MI. Multivariable logistic regression analysis was used to examine the association between SMI and serum cotinine tertiles. SMI was detected in 114 (1.63%) of the participants. The prevalence of SMI was higher among those with higher levels of serum cotinine (SMI prevalence was 1.25%, 1.49%, and 2.14% across serum cotinine lower [0.03 to 0.12 ng/ml], middle [0.12 to 1.39 ng/ml], and higher [1.40 to 1890 ng/ml] tertiles, respectively). In a model adjusted for potential confounders, participants within the highest serum cotinine tertile had significantly greater odds of SMI (odds ratio [95% confidence interval]: 2.51 [1.55 to 4.08]) compared with those with serum cotinine levels in the first tertile. Each 10 ng/ml increase in serum cotinine levels was associated with a 2% (p <0.0001) increase in the prevalence of SMI. This association was stronger in white than nonwhite participants (interaction p value = 0.05). In conclusion, elevated serum cotinine levels are associated with SMI. These findings further highlight the risk associated with passive and active smoking on cardiovascular health and underscore the potential utility of serum cotinine in identifying those at risk.