Pathophysiology of acute coronary syndrome assessed by optical coherence tomography

Optical coherence tomography (OCT) is an optical analogue of intravascular ultrasound (IVUS), which provides high-resolution images of the coronary arteries up to 10microm. OCT allows us to demonstrate clearly culprit lesion morphologies in detail including types of plaque, plaque disruption, thrombus, fibrous cap thickness, and the frequency of thin-capped fibroatheroma (TCFA) in acute coronary syndrome (ACS), as described in previous histological examinations. Furthermore, clinical silent disrupted plaques and non-ruptured TCFAs, which are thought to be precursors of ACS and vulnerable plaques, have also been demonstrated by OCT not only in culprit but also in non-culprit vessels in ACS. OCT also identified the mechanisms of late thrombosis after bare-metal stent and drug-eluting stent implantation. Development of the next-generation frequency-domain OCT system and prospective studies in a large population may allow us to realize the pathophysiology of ACS in detail in vivo in humans, and these may provide us new insights into the etiology and treatment of coronary artery disease in the near future for predicting and preventing ACS.