The main purpose of this study is to examine whether changes in biomarkers during exercise are related to coronary artery disease demonstrated by coronary angiography or echocardiography.

Chest pain/discomfort is a common patient complaint in patients referred to outpatient clinics and emergency departments. The initial goal of evaluation is to exclude potential life threatening conditions like coronary artery disease. Exercise stress testing is a widely available non-invasive test in patients with chest pain and suspected coronary artery disease. However, the sensitivity and specificity of the test is relatively low. Exercise seems to cause an increase in the secretion of B-type natriuretic peptide (BNP), and myocardial ischemia may lead to an even more pronounced increase. Investigators aim to examine whether changes in bloodborne biomarkers such as NT-pro-BNP during exercise may improve the accuracy of exercise stress testing in patients with chest pain/discomfort and a clinical suspicion of coronary artery disease. Also, investigators aim to examine whether changes in biomarkers during exercise are related to cardiac disease demonstrated by echocardiography.

It is known that sudden heavy physical load can trigger myocardial infarction, especially in untrained individuals. The underlying mechanisms are poorly understood and may partly be related to changes in inflammation and haemostasis in patients with coronary artery disease. By measuring markers of inflammation and haemostasis during exercise stress testing, investigators hope to gain new insights into mechanisms responsible for exercise-related myocardial infarction.

Investigators also aim to do a follow-up study to investigate whether results of the initial examinations can relate to future risk of cardiovascular morbidity and mortality.

Inclusion criteria

• Patients referred to Oslo University Hospital Ullevål with chest pain/discomfort of unknown etiology and and a clinical suspicion of coronary artery disease.
• Intermediate or high pre test probability of coronary artery disease.
• Able to give informed, written consent.

Exclusion criteria

• Not able to perform the exercise test.
• Evidence of acute coronary syndrome.
• Known coronary artery stenosis where exercise testing is contraindicated.
• The presence of known moderate to severe valvular heart disease.
• Known heart failure or obvious clinical signs of heart failure.
• Ongoing atrial fibrillation or atrial flutter.
• Complete or partial bundle branch block.
• Digitoxin therapy.
• Pacemaker.
• Renal insufficiency (S-creatinine >150 micromol/L).
• Known pregnancy.

Participants will be recruited from patients with chest pain/discomfort referred for exercise stress testing at Oslo University Hospital, including patients with acute chest pain referred to the emergency department, and referrals to the outpatient clinic.