Smoking in Relation to Coronary Atherosclerotic Plaque Burden, Volume and Composition on Intravascular Ultrasound

Background This study aimed to evaluate the relationship between cigarette smoking and coronary atherosclerotic burden, volume and composition as determined in-vivo by grayscale and virtual histology (VH) intravascular ultrasound (IVUS). Methods and Results Between 2008 and 2011, (VH-) IVUS of a non-culprit coronary artery was performed in 581 patients undergoing coronary angiography. To account for differences in baseline characteristics, current smokers were matched to never smokers by age, gender and indication for catheterization, resulting in 280 patients available for further analysis. Coronary atherosclerotic plaque volume, burden, composition (fibrous, fibro-fatty, dense calcium and necrotic core) and high-risk lesions (VH-IVUS derived thin-cap fibroatheroma (TCFA), plaque burden >= 70%, minimal luminal area <= 4.0 mm(2)) were assessed. Cigarette smoking showed a tendency towards higher coronary plaque burden (mean +/- SD, 38.6 +/- 12.5% in current versus 36.4 +/- 11.0% in never smokers, p = 0.080; and odds ratio (OR) of current smoking for plaque burden above versus below the median 1.69 (1.04-2.75), p = 0.033). This effect was driven by an association in patients presenting with an acute coronary syndrome (ACS) (current smokers, plaque burden 38.3 +/- 12.8% versus never smokers, plaque burden 35.0 +/- 11.2%, p = 0.049; OR 1.88 (1.02-3.44), p = 0.042). Fibrous tissue tended to be lower in current smokers (mean +/- SD, 57.7 +/- 10.5% versus 60.4 +/- 12.6%, p = 0.050) and fibro-fatty tissue was higher in current smokers (median[IQR], 9.6[6.0-13.7]% versus 8.6[5.8-12.2]%, p = 0.039). However, differences in percentage necrotic core and dense calcium could not be demonstrated. Also, no differences were found with regard to high-risk lesions. Conclusions An association between smoking and degree of coronary atherosclerosis was present in patients undergoing coronary angiography who presented with ACS. Although smoking was associated with higher fibro-fatty percentage, no associations could be demonstrated with percentage necrotic core, nor with VH-IVUS derived TCFA lesions. Since the magnitude of the differences in both degree and composition of atherosclerosis was modest, clinical relevance of the findings may be questioned.