The broad objective is to advance our understanding of both in vivo anatomical and functional changes that are present in the coronary arteries in women who have an acute coronary syndrome. Specific focus will be placed on the age of the women as there may be distinct differences in younger women (< 50 years) given the marked increase in mortality in this population.

The hypothesis of the current study is that plaque erosion and microvascular dysfunction are key features responsible for the increased peri-MI mortality in young women. In order to test this hypothesis the following specific aims are proposed using a special intravascular ultrasound technique called virtual histology and microvascular function (effect of intracoronary adenosine on coronary blood flow) in patients coming to the cardiac catheterization laboratory with an acute MI:

1. To determine if plaque rupture or plaque erosion is more prevalent in young women (<50 years) compared with older women (≥ 50 years) and men in the development of an acute MI
2. To determine if inflammatory mediators of plaque rupture are higher in older women and men with an acute MI compared with younger women
3. To determine if microvascular function is abnormal in young women undergoing percutaneous coronary revascularization with an acute MI compared to older women and men
4. To determine if alterations exist in the number and function of EPCs in young women (<50 years) compared with older women (≥ 50 years) and men who have had an acute MI and to determine the association with microvascular function

Inclusion Criteria:

• Age of 18 years or older
• Acute coronary syndrome defined as at least two of the following:

A) an elevated cardiac biomarker (troponin or CK-MB), B) new or dynamic ECG changes in at least 2 contiguous standard electrocardiographic leads of ST depression > 1 mm or ST elevation of >1 mm or T-wave inversions, C) chest pain or discomfort of at least 15 minutes duration, D) a new wall motion abnormality by echocardiography

• Patient who is undergoing coronary angiography
• Physician planning to perform IVUS for treatment of the infarct-related vessel

Exclusion Criteria:

• Creatinine > 2.0 mg/dL (most recent)
• Hemodynamically unstable patients (systolic blood pressure < 90 mmHg or heart rate > 110 beats/ minute or presence of an intra-aortic balloon pump)
• Coronary revascularization (percutaneously or surgically) within 6 months
• The use of chronic immunosuppressive agents
• No target lesion was found at the time of cardiac catheterization that will be percutaneously intervened upon (the patient must undergo percutaneous coronary intervention)
• Inability to give informed consent
• Pregnant or lactating women
• Prisoners