Effect of smoking cessation on cardiac troponin I concentrations

Chronic elevation of cardiac troponin I (cTnI) is associated with heart failure and cardiovascular death. Paradoxically, observational studies have indicated that current smokers have lower cTnI concentrations than non-smokers. We examined determinants of cTnI in smokers and the effect of smoking cessation on cTnI. Overweight or obese smokers received motivational support and varenicline to aid cessation and dietary advice to limit weight gain. Quitters were defined according to the Russell standard (≤5 cigarettes after the quit date) and validated with expired breath CO <10 ppm. Of the total 122 participants, 108 completed assessments at 12 weeks and 78 were classified as quitters versus 30 who continued smoking. cTnI was measured with a high-sensitivity assay with a limit of detection of 1.2 ng/L (Abbott Diagnostics), and concentrations (log-transformed) were compared between quitters and continuing smokers. cTnI concentrations were significantly higher in men than women and correlated with age, but not with number of cigarettes/day. Quitters had median baseline and 12-week levels of 1.4 ng/L (interquartile range [IQR] 1.2-2.5) and 1.4 ng/L (IQR 1.2-2.4), respectively, while nonquitters had baseline and 12-week levels of 1.5 ng/L (IQR 1.2-2.9) and 1.8 ng/L (IQR 1.3-3.4), respectively. The change in cTnI concentrations from baseline to 12 weeks did not differ between quitters and continuous smokers (p = .7). The results suggest that smoking cessation does not affect levels of cTnI, a marker of chronic subclinical myocardial injury, in contrast to prior observational data suggesting that tobacco smoking is associated with lower cTn concentrations.