Controlled Exposures to Air Pollution in Patients With Coronary Heart Disease

Brief Summary

Official Title: “The Effects of Air Pollution on Vascular and Endogenous Fibrinolytic Function in Patients With Coronary Heart Disease”

Air pollution is a major cause of cardiovascular morbidity and mortality. The components of air pollution responsible and the mechanisms through which they might mediate these harmful effects remain only partially understood. We hypothesise that these adverse effects are mediated by combustion derived air pollutants and that even a brief exposure will effect heart and blood vessel function. We assess the effect of dilute diesel exhaust inhalation at levels encountered in urban road traffic on heart and blood vessel function in patients with stable coronary heart disease.

  • Study Type: Interventional
  • Study Design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double-Blind, Primary Purpose: Prevention

Detailed Clinical Trial Description

Observational studies suggest that exposure to air pollution may worsen symptoms of angina and trigger acute myocardial infarction. These findings are limited by imprecision in the measurement of pollution exposure, the effect of potential confounding environmental and social factors, and the lack of mechanistic data. Controlled exposures of air pollutants can help to address these shortcomings by providing a precisely defined exposure in a regulated environment that facilitates investigation with validated biomarkers and surrogate measures of cardiovascular health. Using a carefully characterised exposure system, we have previously shown in healthy volunteers that exposure to dilute diesel exhaust causes lung inflammation, depletion of airway antioxidant defences, and impairment of vascular and fibrinolytic function. To date, there have been no controlled exposures in patients with coronary heart disease: an important population who may be particularly susceptible to the adverse cardiovascular effects of air pollution.

In a double blind randomized cross-over study, 20 patients with prior myocardial infarction will be exposed to dilute diesel exhaust (300µg/m3) or filtered air during periods of rest and moderate exercise in a controlled exposure facility. During the exposure, myocardial ischemia will be quantified by ST-segment analysis using continuous 12-lead electrocardiography. Six hours following exposure, vascular vasomotor and fibrinolytic function will be assessed by means of intra-arterial agonist infusions.

Interventions Used in this Clinical Trial

  • Behavioral: Exposure to dilute diesel exhaust (300µg/m3) or filtered air

Outcome Measures for this Clinical Trial

Primary Measures

  • Exercise induced myocardial ischemia
  • Vascular vasomotor function
  • Endogenous fibrinolytic function

Criteria for Participation in this Clinical Trial

Inclusion Criteria

  • Previous myocardial infarction (>6 months previously) treated by primary angioplasty and stenting
  • On standard secondary preventative therapy

Exclusion Criteria

  • Angina pectoris (Canadian Cardiovascular Society grade ≥2)
  • History of arrhythmia
  • Diabetes mellitus
  • Uncontrolled hypertension
  • Renal or hepatic failure
  • Unstable coronary disease (acute coronary syndrome or unstable symptoms within 3 months)
  • Occupational exposure to air pollution
  • Current smokers
  • Asthma
  • Inter-current illness

Gender Eligibility for this Clinical Trial: Both

Minimum Age for this Clinical Trial: 18 Years

Maximum Age for this Clinical Trial: 70 Years

Are Healthy Volunteers Accepted for this Clinical Trial: No

Clinical Trial Investigator Information

  • Lead Sponsor
    • University of Edinburgh
  • Collaborator
    • Umeå University
  • Overall Official(s)
    • David E Newby, MD, Principal Investigator, The University of Edinburgh
    • Thomas Sandstrom, MD, Principal Investigator, Umeå University


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