Age-related effects of smoking on coronary artery disease assessed by gray scale and virtual histology intravascular ultrasound.

Although smoking is a risk factor for coronary atherosclerosis, the age-related impact on lesion morphology has not been studied. The aim of this study was to assess the age-related impact of smoking on the extent of atherosclerosis and arterial remodeling. In Providing Regional Observations to Study Predictors of Events in the Coronary Tree, 687 patients with acute coronary syndrome underwent 3-vessel gray scale and virtual histology intravascular ultrasound imaging of 3,185 nonculprit lesions. In 207 patients ≤65 years, current (smoking within 1 month) and former (no smoking for >1 month) smokers showed significantly smaller normalized volumes of external elastic membrane (EEM), lumen, and P + M (plaque + media) compared with nonsmokers. At the minimal lumen area site, current and former smokers had significantly smaller EEM, lumen, and P + M areas than nonsmokers. Conversely, in 480 patients >65 years, current smokers had greater normalized P + M volumes than nonsmokers with no difference in normalized EEM or lumen volumes. Finally, in patients >65 years (but not in patients ≤65 years), current smokers showed more plaque ruptures (4.7% vs 1.8%, p = 0.05) and echolucent plaques (8.3% vs 3.9%, p = 0.05) compared with nonsmokers. On multivariable analysis, a history of smoking (combining current and former smoking) predicted smaller normalized EEM volumes compared with nonsmokers ≤65 years. In conclusion, in patients ≤65 years, but not in patients >65 years, smoking had a vascular constrictive effect that contributed to severe luminal stenosis. Conversely, smokers >65 years had more plaque with greater plaque instability.