Association of smoking with the troponin I level and adverse cardiovascular events

Data on the level of cardiac troponin I determined by a high-sensitivity method (hs-cTnI) may improve the accuracy of predicting adverse cardiovascular events in the general population. Some foreign publications describe a decrease in the hs-cTnI level and its prognostic value for adverse outcomes of cardiovascular diseases (CVD) in smokers and ex-smokers. This urges the study of the hs-cTnI predictive ability in the Russian population depending on smoking status. Objective. To analyze the hs-cTnI level association with the smoking status in a population sample from 9 regions of the Russian Federation and test the hypothesis that smoking influences the hs-cTnI predictive ability for adverse CVD outcomes. Material and methods. We analyzed the data of 10.277 people aged 35 to 64 years (60% women) without a history of CVD, previously included in the ESSE-RF and ESSE-RF2 observational multicenter studies (Epidemiology of cardiovascular diseases and their risk factors in the regions of the Russian Federation). For all participants, we knew their smoking status and hs-cTnI levels in blood plasma determined by a highly sensitive microparticle immune chemiluminescence assay. The median follow-up period was 7.5 years. A combined end-point was the death from cardiovascular disease or nonfatal myocardial infarction. Results. Smoking status in men and women did not influence the median hs-cTnI level (p>0.1). During the follow-up, the end-point was achieved in 267 cases, including 114 (1.8%) non-smokers, 66 (3.6%) ex-smokers, and 87 (4.3%) smokers. The hazard ratio analysis for the hs-cTnI gender-specific cut-off levels showed that the probability of reaching an end-point at the hs-cTnI values above the cut-off levels was the highest among ex-smokers and the lowest among smokers; however, the differences did not reach statistical significance. In the ROC analysis to evaluate the predictive ability of hs-cTnI depending on smoking status, the area under the curve (AUC) adjusted for gender, age, and region amounted to 0.799 among non-smokers, 0.819 among ex-smokers, and 0.789 among smokers; the differences did not reach statistical significance. Conclusion. This study evidences that smoking status does not influence the hs-cTnI blood plasma level or the hs-cTnI predictive ability for cardiovascular diseases.