Stefan Söderberg

BACKGROUND: Exposure to air pollution from traffic is associated with adverse cardiovascular events. The mechanisms for this association are unknown. We conducted a controlled exposure to dilute diesel exhaust in patients with stable coronary heart disease to determine the direct effect of air pollution on myocardial, vascular, and fibrinolytic function. METHODS: In a double-blind, randomized, crossover study, 20 men with prior myocardial infarction were exposed, in two separate sessions, to dilute diesel exhaust (300 mug per cubic meter) or filtered air for 1 hour during periods of rest and moderate exercise in a controlled-exposure facility. During the exposure, myocardial ischemia was quantified by ST-segment analysis using continuous 12-lead electrocardiography. Six hours after exposure, vasomotor and fibrinolytic function were assessed by means of intraarterial agonist infusions. RESULTS: During both exposure sessions, the heart rate increased with exercise (P<0.001); the increase was similar during exposure to diesel exhaust and exposure to filtered air (P=0.67). Exercise-induced ST-segment depression was present in all patients, but there was a greater increase in the ischemic burden during exposure to diesel exhaust (-22+/-4 vs. -8+/-6 millivolt seconds, P<0.001). Exposure to diesel exhaust did not aggravate preexisting vasomotor dysfunction, but it did reduce the acute release of endothelial tissue plasminogen activator (P=0.009; 35% decrease in the area under the curve). CONCLUSIONS: Brief exposure to dilute diesel exhaust promotes myocardial ischemia and inhibits endogenous fibrinolytic capacity in men with stable coronary heart disease. Our findings point to ischemic and thrombotic mechanisms that may explain in part the observation that exposure to combustion-derived air pollution is associated with adverse cardiovascular events. (ClinicalTrials.gov number, NCT00437138 [ClinicalTrials.gov].).

Cortisol has been implicated as a pathophysiological mediator in idiopathic obesity, but circulating cortisol concentrations are not consistently elevated. The tissue-specific responses to cortisol may be influenced as much by local prereceptor metabolism as by circulating concentrations. For example, in liver and adipose tissue cortisol is regenerated from inactive cortisone by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). In obese Zucker rats 11beta-HSD1 activity is reduced in liver but enhanced in adipose tissue. This study addressed whether the same tissue-specific disruption of cortisol metabolism occurs in human obesity. 34 men were recruited from the MONICA population study in Northern Sweden to represent a wide range of body composition and insulin insensitivity. Plasma cortisol was measured at 0830h and 1230h, after overnight low-dose dexamethasone suppression, after intravenous corticotropin releasing hormone (CRH), and after oral cortisone administration. Urinary cortisol metabolites were measured in a 24 h sample. A subcutaneous fat biopsy was obtained from 16 participants to measure cortisol metabolism in vitro. Higher body mass index was associated with increased total cortisol metabolite excretion (r = 0.47, p < 0.01), but lower plasma cortisol at 1230 h and after dexamethasone, and no difference in response to CRH. Obese men excreted a greater proportion of glucocorticoid as metabolites of cortisone rather than cortisol (r = 0.43, p < 0.02), and converted less cortisone to cortisol after oral administration (r = 0.49, p < 0.01), suggesting impaired hepatic 11beta-HSD1 activity. By contrast, in vitro 11beta-HSD1 activity in subcutaneous adipose tissue was markedly enhanced in obese men (r = 0.66, p < 0.01). We conclude that in obesity, reactivation of cortisone to cortisol by 11beta-HSD1 in liver is impaired, so that plasma cortisol levels tend to fall, and there may be a compensatory increase in cortisol secretion mediated by a normally functioning hypothalamic-pituitary-adrenal axis. However, changes in 11beta-HSD1 are tissue-specific: strikingly enhanced reactivation of cortisone to cortisol in subcutaneous adipose tissue may exacerbate obesity; and it may be beneficial to inhibit this enzyme in adipose tissue in obese patients.

Aims: Guidelines recommend a goal-oriented treatment approach in pulmonary arterial hypertension (PAH). The aim is to reach a low-risk profile, as determined by a risk assessment instrument. This strategy is incompletely validated. We aimed to investigate the bearing of such risk assessment and the benefit of reaching a low-risk profile. Methods and results: Five hundred and thirty PAH patients were included. Follow-up assessments performed after a median of 4 (interquartile range 3-5) months were available for 383 subjects. Patients were classified as 'Low', 'Intermediate', or 'High risk' and the benefit of reaching the 'Low risk' group was estimated. Survival differed (P < 0.001) between the risk groups at baseline and at follow-up. Survival was similar for patients who remained in or improved to the 'Low risk' group. Survival was similar for patients who remained in or worsened to the 'Intermediate risk' or 'High risk' groups. Irrespective of follow-up risk group, survival was better (P < 0.001) for patients with a higher proportion of variables at low risk. Results were unchanged after excluding patients with idiopathic PAH >65 years at diagnosis, and when patients with idiopathic or connective tissue disease-associated PAH were analysed separately. Patients in the 'Low risk' group at follow-up exhibited a reduced mortality risk (hazard ratio 0.2, 95% confidence interval 0.1-0.4 in multivariable analysis adjusted for age, sex and PAH subset), as compared to patients in the 'Intermediate risk' or 'High risk' groups. Conclusion: These findings suggest that comprehensive risk assessments and the aim of reaching a low-risk profile are valid in PAH.

Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.

Background: Atrial fibrillation (AF) is a common cardiac disease in aging populations with high comorbidity and mortality. Sex differences in AF epidemiology are insufficiently understood. Methods: In N=79 793 individuals without AF diagnosis at baseline (median age, 49.6 years; age range, 24.1–97.6 years; 51.7% women) from 4 community-based European studies (FINRISK, DanMONICA, Moli-sani Northern Sweden) of the BiomarCaRE consortium (Biomarker for Cardiovascular Risk Assessment in Europe), we examined AF incidence, its association with mortality, common risk factors, biomarkers, and prevalent cardiovascular disease, and their attributable risk by sex. Median follow-up time was 12.6 (to a maximum of 28.2) years. Results: Fewer AF cases were observed in women (N=1796; 4.4%), than in men (N=2465; 6.4%). Cardiovascular risk factor distribution and lipid profile at baseline were less beneficial in men than in women, and cardiovascular disease was more prevalent in men. Cumulative incidence increased markedly after the age of 50 years in men and after 60 years in women. The lifetime risk was similar (&gt;30%) for both sexes. Subjects with incident AF had a 3.5-fold risk of death in comparison with those without AF. Multivariable-adjusted models showed sex differences for the association of body mass index and AF (hazard ratio per standard deviation increase, 1.18; 95% confidence interval [CI], 1.12–1.23 in women versus 1.31; 95% CI 1.25–1.38 in men; interaction P value of 0.001). Total cholesterol was inversely associated with incident AF with a greater risk reduction in women (hazard ratio per SD, 0.86; 95% CI, 0.81–0.90 versus 0.92; 95% CI, 0.88–0.97 in men; interaction P value of 0.023). No sex differences were seen for C-reactive protein and N-terminal pro B-type natriuretic peptide. The population-attributable risk of all risk factors combined was 41.9% in women and 46.0% in men. About 20% of the risk was observed for body mass index. Conclusions: Lifetime risk of AF was high, and AF was strongly associated with increased mortality both in women and men. Body mass index explained the largest proportion of AF risk. Observed sex differences in the association of body mass index and total cholesterol with AF need to be evaluated for underlying pathophysiology and relevance to sex-specific prevention strategies.