The multicenter observational CLIMA registry has been conceived to explore correlation between OCT morphology of atherosclerotic plaques located in the left anterior descending artery with mid and long term clinical outcome.

Acute myocardial infarction (MI) is commonly caused by plaque ulceration and subsequent local thrombosis. Plaques that tend to rupture are typically characterized by a large superficial lipid pool, delimited by a thin fibrous cap and often exhibit local signs of inflammation. Such atherosclerotic lesions are commonly described as vulnerable plaques (1-4).

Identification of these plaque features with imaging modalities is potentially a valid approach to identify patients at increased risk of M (5). Optical coherence tomography is capable of visualizing superficial plaque components at a high resolution (in the range of 10-15 microns) and can depict all the features of plaque vulnerability or thrombogenicity (6,7).

The aim of the study is to relate presence of multiple OCT criteria of plaque vulnerability with following clinical events in a subset of coronary lesions. For this purpose all plaques in the proximal-mid portion of the left anterior descending artery will be evaluated with FD-OCT assessing the following criteria:

• minimum lumen area (MLA) <3.5 mm2:
• fibrous cap minimum thickness <75 µm:
• lipid arc extension >180°;
• presence of macrophages;

Inclusion Criteria:

• Age >18 years;
• Patients with clinical indication to coronary angiography undergoing OCT evaluation of the left anterior descending artery regardless of the clinical syndrome;
• Patients with at least 30 mm of naïve OCT-assessable proximal-mid left anterior descending artery;
• Patient has been informed of the nature of the study and agrees to its provisions and has provided written informed consent to the procedure;

Exclusion Criteria:

• Female with childbearing potential or lactating;
• Acute or chronic renal dysfunction (defined as creatinine greater than 2.0 mg/dl);
• Advanced heart failure (NYHA III-IV)
• Previous Coronary artery by-pass surgery
• Previous stenting of proximal-mid left anterior descending artery with residual untreated segment <30mm.
• Co-morbidities that could interfere with completion of study procedures, or life expectancy less than 1 year;
• Participating in another investigational drug or device trial that has not completed the primary endpoint or would interfere with the endpoints of this study;
• Heavily calcified vessel and/or lesion which cannot be successfully imaged by OCT

All consecutive subjects undergoing OCT assessment of the proximal left descending artery coronary during coronary angiography should be screened for eligibility.

Patients will be enrolled from participating centers at the time of OCT assessment and prospectively investigated to evaluate clinical outcome.