Discovery of New Circulating Biomarkers of Coronary Atherosclerosis

Hypothesis: Our hypothesis is that coronary atherosclerosis induces both quantitative and qualitative modifications of circulating proteins, which can be captured by a differential proteomic approach applied to serum or plasma samples. Identification of such modifications in the circulating blood of patients with coronary artery disease (versus patients without coronary artery disease) and/or of patients with acute coronary syndromes (versus stable coronary artery disease) may lead to discovery of new biomarkers of coronary atherosclerosis and of atherosclerotic plaque vulnerability.

Objectives:

Primary objective: Identification of new circulating biomarkers of stable and unstable coronary artery disease using a new approach of differential proteomics.

Secondary objectives:

• Evaluation of the diagnostic value of these new biomarkers for the diagnosis of stable and unstable coronary artery disease.
• Comparison of the diagnostic value of these new biomarkers to the diagnostic value of 1) other validated biomarkers of atherosclerosis (eg, CRP, IL-6, CD40L, markers of leukocyte activation, …); and 2) of non-invasive measures of arterial function (eg, carotid artery intima-media thickness, pulse wave velocity, ankle/brachial index, …)
• Description of the relationship between these new biomarkers and major adverse coronary events (death, myocardial infarction, revascularization) during a 12-month follow-up.

Methods:

Uniq center, prospective study. Three groups of patients will be studied. Group 1: Non-ST-elevation acute myocardial infarction; Group 2: Stable coronary artery disease; Group 3: normal coronary arteries and absence of other detectable atherosclerotic lesions.

A new proteomic approach will be applied to serum and plasma samples obtained 1 month after the index hospitalisation. This approach includes 3 steps: 1) equalisation of circulating proteins (expose low-concentration proteins belonging to the "deep-proteome"); 2) Retention chromatography; and 3) protein separation using 2D-electrophoresis and Surface-Enhanced Laser Desorption/Ionisation Time-of-Flight (SELDI-TOF).

Biomarkers with the highest diagnostic value will be subsequently identified using Matrix-Assisted Laser Desorbtion/Ionisation Time-of-Flight (MALDI-TOF) and tandem mass spectrometry (MS/MS).

Perspectives:

Validation of the diagnostic and prognostic values of the new biomarkers discovered and identified using the proteomic approach described above will require development of more straightforward measurement techniques (eg, ELISA), which will be used prospectively or retrospectively in other cohorts of patients with coronary artery disease. Basic studies will be performed in parallel, so as to better understand the role of these new biomarkers in the pathophysiology of atherosclerosis.

Inclusion criteria

• Group 1 (Non-ST-elevation acute myocardial infarction) :

• Chest pain less than 48 hours before admission,
• And modifications of ST-T (no persistent ST elevation) on 12-lead EKG,
• And elevation of troponin-I >1xN,
• And presence of ≥1 de novo stenosis(es) >50% located on ≥1 native coronary artery(ies) and successfully treated using percutaneous coronary intervention and stenting.
• Group 2 (Stable coronary artery disease) :

• Documented myocardial ischemia (stable angina or positive stress test)
• And presence of ≥1 de novo stenosis(es) >50% located on ≥1 native coronary artery(ies) and successfully treated using percutaneous coronary intervention and stenting.
• Group 3 (Normal coronary arteries) :

• No history of coronary artery disease, neurovascular disease or peripheral artery disease,
• And normal coronary angiography performed because of suspected coronary artery disease
• And absence of significant functional or anatomic abnormalities suggestive of atherosclerosis on non-invasive arterial studies (measurements of intima-media thickness, pulse wave velocity, ankle-brachial index, …).

Exclusion criteria

• Group 1 :

• Preexisting EKG abnormalities (including left bundle branch block) precluding accurate assessment of ST-T changes
• Group 2 :

• History of acute coronary syndrome
• Groups 1 and 2:

• Culprit coronary artery stenosis is a restenosis or a stent thrombosis or is located in a bypass graft.
• All groups :

• Heart failure (NYHA class ≥II)
• Left ventricular ejection fraction <50%
• Severe valvular heart disease requiring surgical or percutaneous therapy
• History of autoimmune, inflammatory or neoplasia diseases ; or infectious disease in the month before admission
• Life expectancy < 1 year
• Age <18 years or >80 years
• Current pregnancy or breast-feeding
• Homeless or travelers who may not be followed-up
• Refusal to sign the informed consent form