Effect of cigarette smoking on carotid IMT and FRS

Objective: To investigate 1) whether smokers and no smokers with identical Framingham risk score (FRS) have a different subclinical vascular damage and 2) whether moderate cigarette smoking throughout the life (in terms of packyears, a measure of total exposure to cigarette smoking not considered in the FRS) may be considered harmless as compared to the effects of heavy cigarette smoking on the extent of sub-clinical atherosclerosis. Methods: Carotid IMTs of never-, moderate- (packyears<30) and heavy-smokers (packyears≥30), matched for age, gender and FRS, were compared (n=72 per group). Results: As a result of the FRS-matching, moderate- and heavy-smokers were fully comparable for all the vascular risk factors (VRFs) included into the algorithm. In contrast, never-smokers had, consequently to the matching, higher levels of total and LDL-cholesterol, blood glucose, systolic and diastolic blood pressure (all p<0.05). The IMTmean of both heavy- (1.05±0.31 mm) and moderate-smokers (1.02±0.27 mm) was significantly higher than in FRS-matched never-smokers (0.92±0.28 mm), (p=0.01 and p=0.003, respectively). Thus, regardless of a moderate or heavy smoking history, smokers show a worse carotid atherosclerotic profile than FRS-matched never smokers. Conclusions: Cigarette smoking, whatever moderate or heavy, induces a vascular damage that exceeds that observed in never smokers matched for FRS, which reveals the particularly strong atherogenicity of this risk factor. Moderate cigarette consumption, as defined in this study, may not be considered a harmless alternative to smoking cessation. Funding: Research supported in part by Philip Morris USA Inc. and Philip Morris International.