Subclinical atherosclerosis, airflow obstruction and emphysema: the MESA Lung Study

The association of systemic microvascular changes with lung function and lung density: a cross-sectional study

Smoking causes endothelial dysfunction and systemic microvascular disease with resultant end-organ damage in the kidneys, eyes and heart. Little is known about microvascular changes in smoking-related lung disease. We tested if microvascular changes in the retina, kidneys and heart were associated with obstructive spirometry and low lung density on computed tomography. The Multi-Ethnic Study of Atherosclerosis recruited participants age 45-84 years without clinical cardiovascular disease. Measures of microvascular function included retinal arteriolar and venular caliber, urine albumin-to-creatinine ratio and, in a subset, myocardial blood flow on magnetic resonance imaging. Spirometry was measured following ATS/ERS guidelines. Low attenuation areas (LAA) were measured on lung fields of cardiac computed tomograms. Regression models adjusted for pulmonary and cardiac risk factors, medications and body size. Among 3,397 participants, retinal venular caliber was inversely associated with forced expiratory volume in one second (FEV(1)) (P<0.001) and FEV(1)/forced vital capacity (FVC) ratio (P = 0.04). Albumin-to-creatinine ratio was inversely associated with FEV(1) (P = 0.002) but not FEV(1)/FVC. Myocardial blood flow (n = 126) was associated with lower FEV(1) (P = 0.02), lower FEV(1)/FVC (P = 0.001) and greater percentage LAA (P = 0.04). Associations were of greater magnitude among smokers. Low lung function was associated with microvascular changes in the retina, kidneys and heart, and low lung density was associated with impaired myocardial microvascular perfusion. These cross-sectional results suggest that microvascular damage with end-organ dysfunction in all circulations may pertain to the lung, that lung dysfunction may contribute to systemic microvascular disease, or that there may be a shared predisposition.

Chlamydia pneumoniae and progression of subclinical atherosclerosis

BACKGROUND

Cross-sectional investigation between presence of antibodies and coronary artery calcification (CAC) in past studies has shown no relationship, but progression over time has not been investigated. The objective of this study was to determine the relationship between presence of Chlamydia pneumoniae antibodies and progression of CAC and ankle-brachial index (ABI).

DESIGN

The Multiethnic Study of Atherosclerosis (MESA) is a prospective population-based cohort of racially and ethnically diverse male and female participants recruited from six communities in the USA, age 45-84 years, free of clinical cardiovascular disease at baseline.

METHODS

The main outcomes were progression of mean CAC and ABI between exams 1 (2000-02) and 3 (2004-05) (median follow-up of 3.13 years) by C. pneumoniae antibody. Multivariate models adjusting for demographics, obesity, smoking, alcohol use, and physical activity were computed.

RESULTS

Of 2223 subjects analysed, 76% were positive for C. pneumoniae antibodies. Progression of CAC was significantly higher in the antibody-positive group (93.8 vs. 78.2 agatston units, p = 0.02) and in antibody-positive subjects with CAC ≥10 at baseline (216.5 vs. 178.6, p = 0.02) than antibody-negative group. Smoking and body mass index ≥30 kg/m(2) both had interactions with presence of C. pneumoniae yielding significantly greater CAC progression. Progression of ABI did not significantly differ by C. pneumoniae antibody status in models adjusted for covariates.

CONCLUSIONS

C. pneumoniae antibodies are related to progression of CAC, particularly in individuals with CAC present at baseline. This provides evidence that certain groups are at higher risk of atherosclerotic progression and may be useful for risk stratification and treatment.

Childhood air pollutant exposure and carotid artery intima-media thickness in young adults

BACKGROUND

Exposure to ambient air pollutants increases risk for cardiovascular health outcomes in adults. The contribution of childhood air pollutant exposure to cardiovascular health has not been thoroughly evaluated.

METHODS AND RESULTS

The Testing Responses on Youth study consists of 861 college students recruited from the University of Southern California in 2007 to 2009. Participants attended 1 study visit during which blood pressure, heart rate, and carotid artery intima-media thickness (CIMT) were assessed. Self-administered questionnaires collected information about health and sociodemographic characteristics, and a 12-hour fasting blood sample was drawn for lipid and biomarker analyses. Residential addresses were geocoded and used to assign cumulative air pollutant exposure estimates based on data derived from the U.S. Environmental Protection Agency's Air Quality System database. The associations between CIMT and air pollutants were assessed using linear regression analysis. Mean CIMT was 603 μm (±54 SD). A 2 standard deviation (SD) increase in childhood (aged 0-5 years) or elementary school (aged 6-12 years) O(3) exposure was associated with a 7.8-μm (95% confidence interval, -0.3-15.9) or 10.1-μm (95% confidence interval, 1.8-18.5) higher CIMT, respectively. Lifetime exposure to O(3) showed similar but nonsignificant associations. No associations were observed for PM(2.5), PM(10), or NO(2), although adjustment for these pollutants strengthened the childhood O(3) associations.

CONCLUSIONS

Childhood exposure to O(3) may be a novel risk factor for CIMT in a healthy population of college students. Regulation of air pollutants and efforts that focus on limiting childhood exposures continue to be important public health goals.

The epidemiology of vascular dysfunction relating to chronic obstructive pulmonary disease and emphysema

Cor pulmonale has long been described in very severe chronic obstructive pulmonary disease (COPD) and emphysema. Cross-sectional results from population-based studies show that left ventricular filling and a variety of vascular measures in the systemic circulation are abnormal in preclinical COPD and emphysema and that a predominant vascular change in COPD and emphysema is endothelial and microvascular dysfunction. These findings suggest that pulmonary vascular changes may occur early in COPD and emphysema and might contribute to pathogenesis. However, longitudinal epidemiologic studies with direct measures of the pulmonary vasculature are lacking; therefore, inferences are limited at present. New imaging-based approaches to the assessment of the pulmonary vasculature are applicable to epidemiologic studies and may help in defining the relationship of pulmonary vascular damage to progression of COPD and emphysema. These measures may also provide imaging-based surrogate markers, and novel therapeutics targeted to the pulmonary vasculature might reduce symptoms and improve function in these common diseases.