Lung Function Impairment Is Related to Subclinical Atherosclerosis Only in Active Smokers

Background: Although an association between lung function and subclinical atherosclerosis has been reported, it remains unclear whether this association is only driven by tobacco smoking. We aimed to assess this in a population with at least one cardiovascular risk factor. Methods: We recruited 6209 subjects aged between 45 and 70 years with at least one cardiovascular risk factor (excluding diabetes mellitus) participating in the ILERVAS project 2015–2018. Lung function was determined by spirometry. Subclinical atherosclerosis was assessed with the ankle–brachial index (ABI) and the presence of carotid and femoral plaques measured by ultrasound. Results: A total of 5927 subjects were included: 49% male, median (p25–p75) age 57 years (52–62). Plaques were found in 4337 (73.2%) of the subjects. The patients with atherosclerosis showed worse lung function: median forced expiratory volume in one second (FEV1) 95% and forced vital capacity (FVC) 94% in the patients with plaques vs. 99% and 98% in the other patients (p < 0.001). Adjusted models stratified by smoking status showed that being in the lower quartiles of FEV1 % was associated with carotid and femoral plaques (OR 1.599, p = 0.005; and OR 1.654, p = 0.006), whereas FVC % was inversely associated with carotid plaques (OR 0.967, p = 0.041). A pathological ABI was associated with worse FEV1 (OR 1.971, p = 0.038) and the presence of airway obstruction (OR 1.658, p = 0.015). However, these differences were restricted to current smokers. Conclusions: Lung function impairment was correlated with subclinical atherosclerosis only in current smokers. This highlights the unique role of smoking-related vascular and pulmonary dysfunction in early stages of pulmonary and cardiovascular afflictions.