The iWONDER trial has the following objective:

To analyze the morphological, phenotypic and tissue characteristics of atherosclerotic plaques angiographically considered "culprit" and "not-culprit" in patients undergoing coronary angiography due to STEMI (ST-elevation myocardial infarction).

Coronary artery angiography (CA) is a two-dimensional silhouette of the arterial lumen from a complex three dimensional vascular structure. This exam has several limitations already well documented, including shortening of the vessel, overlapping images, intra and inter-observer variability during the consideration of the severity of injuries. Besides, it offers great limitations in the diagnosis of the composition of atherosclerotic plaque. Furthermore, intravascular ultrasound (IVUS) provides a sensitive and reproducible measure of the dimensions of the vessel and allows direct visualization of the vessel wall, atherosclerotic plaque and arterial lumen. The utility of grayscale IVUS as prognostic tool and as a guide in percutaneous coronary interventions (PCI) is well established. More recently, IVUS has also provided new insights for safety and efficacy of drug eluting stent (DES).

Advances in technology now allow IVUS to characterize the morphology and composition of plaques. Specifically, the analysis of the IVUS wave frequency - beyond the interpretation of wave lengths used in grayscale IVUS- enables in vivo analysis of atherosclerotic plaque composition with high sensitivity and specificity. Although previous studies have reported data using IVUS radiofrequency analysis, the use of a new modality (iMapTM, Boston Scientific, Santa Clara, CA, USA) for characterization of atherosclerotic plaque is poorly known.

Inclusion Criteria:

• Age < 75 years
• Diagnosis of NSTEMI/STEMI with prior use of fibrinolytics in the past 7 days
• Signature of the Term of Informed Consent

Exclusion Criteria:

• Hemodynamic instability
• Clinical signs of post-AMI ventricular dysfunction (Killip III/IV)
• Angiographic findings of (1)coronary anatomy with significant tortuosity, (2) critical coronary obstruction preventing the passage of the IVUS catheter and (3) total occlusion of any of the three epicardial coronary arteries.