Myocardial Ischaemia After Exposure to Diesel Exhaust (MIDAS)

University of Edinburgh

Status: Completed

Conditions: Coronary Heart Disease

Treatments: Other: Coronary blood flow measured by doppler echocardiography; Other: CT/PET Myocardial Perfusion Imaging using O-15 water

Study type: Interventional

Funder types: Other

Identifiers

NCT01661582

MIDAS

Details and patient eligibility

About

Exposure to particulate air pollution is associated with increases in cardiovascular mortality and morbidity. The pathophysiological mechanisms underlying this observation are emerging, and exposure to particulate air pollution has been shown to result in increases in blood pressure and arterial tone, impaired vascular function and an increased tendency for blood to clot as well as an increase in atherosclerotic plaque burden. Recent evidence from panel studies and controlled exposure studies have suggested an increase in myocardial ischaemia (a reduction in blood flow to the heart) following exposure. In this study we aim to investigate directly myocardial (heart) blood flow following exposure to diesel exhaust (as a model of urban air pollution) using CT/PET myocardial perfusion imaging in male patients with stable coronary disease and healthy male controls. We hypothesize that following exposure to dilute diesel exhaust:

1. Myocardial blood flow will be reduced
2. Coronary flow reserve will be impaired
3. The magnitude of impairment will be higher in patients with coronary disease as compared to healthy controls

Enrollment: 28 patients

Sex: Male

Ages: 18 to 60 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Healthy volunteers will be taking no regular medication, have a normal electrocardiogram and exercise stress test
• Patients with a previous history of myocardial infarction or successful coronary revascularization (PTCA or coronary artery bypass grafting) but without symptoms of angina pectoris will be recruited

Exclusion criteria

• Healthy volunteers:
• Regular medication
• Abnormal 12-lead electrocardiogram
• Abnormal exercise stress test
• Patients with coronary disease
• Acute coronary syndrome within past 3 months
• Impaired left ventricular function
• Significant valvular heart disease
• Left ventricular hypertrophy
• Resting conduction defect
• Digoxin use
• Renal impairment (eGFR <60 mL/min)
• Hepatic impairment
• Asthma

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Quadruple Blind

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28 participants in 2 patient groups, including a placebo group

Filtered Air Exposure

Placebo Comparator group

Description:

Subjects will be exposed to filtered air for 1 hour during intermittent exercise in a purpose-built exposure facility

Treatment:

Other: Coronary blood flow measured by doppler echocardiography

Other: CT/PET Myocardial Perfusion Imaging using O-15 water

Dilute Diesel Exhaust Exposure

Experimental group

Description:

Subjects will be exposed to dilute diesel exhaust (\~300 mcg/m3) for 1 hour during intermittent exercise in a purpose-built exposure facility

Treatment:

Other: Coronary blood flow measured by doppler echocardiography

Other: CT/PET Myocardial Perfusion Imaging using O-15 water