In recent years, medical research into the cause and progression of heart disease due to narrowing and blockage of blood vessels to the heart muscle has improved the understanding of ischemic heart disease. It is now accepted that both the development and later progression with sudden blockage of blood vessels are associated with inflammation, although it remains unknown exactly what triggers this inflammatory process. It is possible that new blood tests which measure markers of inflammation in the bloodstream may be useful to help identify patients at risk of heart damage and assess response to treatment.

The study plans to assess a new blood test for a known marker of inflammation (IL-4) in patients with heart disease.

The hypothesis of this study is that, the cytokine, IL-4, measured by a new assay, is abnormally elevated in the blood of patients with coronary artery disease.

Also hypothesized is that the degree of abnormality of blood IL-4, is related to important clinical events in such patients, including severity of disease, acute complications, and treatment.

This is a single centre, prospective, non randomised, non controlled, pilot study of the potential abnormality of a new test group of patients in whom the results are postulated to be abnormal.

The specific aims of the study are:

1. To measure IL-4 by a new rapid on-site technique in patients with documented coronary artery disease presenting in a variety of acute clinical circumstances
2. To evaluate any abnormal measurements in relation to the severity of the disease, acute vascular complication and newly prescribed medications.

It is proposed to study 4 small groups of patients with ischemic heart disease.

1. Patients with unstable coronary artery disease admitted to the Coronary Care Unit. They will be studied on admission and then daily until coronary angiography is performed.
2. Patients having coronary angioplasty. They will be studied before, immediately after and 24 hours after the procedure.
3. Patients having coronary artery bypass grafting will be studied immediately after and 24 hours post surgery.
4. Patients with stable coronary artery disease about to receive a statin and or angiotensin-converting enzyme inhibitor therapy will be studied before and twice weekly after commencement of therapy for 4 weeks.

Inclusion Criteria:

• All patients (either sex and any age) presenting in the settings described will be eligible to participate.

Exclusion Criteria:

• An unwillingness to participate.