Biomarkers and Coronary Atherosclerotic Burden and Activity as Assessed by Coronary Angiography and Intra-Coronary Imaging Modalities

Coronary artery disease (CAD) is one of the leading causes of death worldwide and it is expected that the rate of CAD will accelerate in the next decade due to overall aging of population and increases in the prevalence of cardiovascular risk factors (type 2 diabetes, obesity, metabolic syndrome) in younger generations (Amborsioni et al., 2003). The mortality associated with atherosclerotic disease is mainly related to the acute coronary syndromes (ACS), including acute myocardial infarction (AMI), unstable angina (UA) pectoris and sudden cardiac death. Inflammation plays a central role throughout the entire disease progression, and it lies at the root of atherosclerosis initiation, progression and its complications (Bonow et al., 2002). However, recent data support the notion that plaques within the coronary circulation become “more severe” or at “high-risk” (vulnerable plaque) in response to a wide array of local and systemic influences, both inflammatory and non-inflammatory (Alsheikh-Ali et al., 2010; Finn AV et al., 2010). Indeed, plaques may have similar structural features and morphologic assessment, but may differ in their biology, their activity, and thus their likelihood of advancing toward clinical complications. Advances in the understanding of the pathogenesis of coronary atheroslcerosis have stimulated development of novel biomarkers, and expanded their role in the different spectra of their underlying pathophysiology (Hochholzer et al., 2010). In this regard, an emerging approach is represented by the assessment of plaque burden, morphology, and remodeling with in vivo atherosclerosis imaging and its correlation to novel biomarkers (Prati & Zimarino, 2010). In the past, invasive coronary angiography (CAG) has been the only diagnostic procedure for identifying coronary atherosclerosis. However, newer intracoronary imaging modalities have been developed allowing a more accurate and precise evaluation of coronary atherosclerotic lesions, with regard to specific morphologic criteria, especially concerning vulnerability. Intravascular ultrasound (IVUS) is a catheter-based technology that allows for assessment of vessel wall thickness and structure while coronary angioscopy also allows to visualize the vessel lumen (Kaneda et al., 2010). More recently, optical coherence