Objectives: The study evaluated whether heavy exposure to environmental tobacco smoke (passive smoking) might damage arterial function in modernized Chinese.
Background: Heavy passive smoking is associated with arterial endothelial dysfunction in Caucasian, but not rural Chinese, subjects.
Methods: We studied 20 young (mean age 36.6 +/- 7.0 years) nonsmoking asymptomatic casino workers (9 men) in Macau who were exposed to environmental tobacco smoke for over 8 h/day for at least two years and 20 normal subjects (control subjects). These two groups were carefully matched for age, gender, body mass index (BMI), blood pressure, vessel diameter, cholesterol and glucose levels. Brachial artery diameter was measured by high-resolution B-mode ultrasound at rest, after flow increase (causing flow-mediated endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator).
Results: Flow-mediated dilation (mean +/- SD% of diameter changes) was significantly lower in passive smokers (6.6 +/- 3.4%) compared with the controls (10.6 +/- 2.3%) (p < 0.0001). Nitroglycerin-induced dilation of the two groups were similar. Upon multivariate analysis, passive smoking exposure was the strongest independent predictor (beta = -0.59; p = 0.0001) for impaired flow-mediated endothelium-dependent dilation (model R2 = 0.75, F value = 6.1, p = 0.0001).
Conclusions: In modernized Chinese, as in Caucasians, exposure to heavy environmental tobacco smoke causes arterial endothelial dysfunction, a key early event in atherosclerosis. This may have serious implications for cardiovascular health in China, currently in a process of rapid modernization.