This chapter provides a detailed description of the role of the OCT technique in the clinical practice. A review section on data from clinical studies is provided, underlining the extent usage of OCT during the last years. Finally, the capability of OCT to assess ambiguous lesions and deferral of interventions is discussed just before describing the role of the technique during the post procedural assessment.
TopIntroduction
The introduction of stents in clinical practice was initially burdened by an unacceptably high incidence of sub-acute thrombosis. Later on the use of intravascular ultrasound (IVUS) opened the way to the understanding the reasons for stent failure. IVUS clarified that despite optimal angiographic results many first generation stents were still having a marked under-expansion with irregular eccentric lumen and incomplete apposition of the stent struts to the vessel wall. These findings led to a new strategy for stent deployment based on high-pressure balloon dilatation inside the stent, to be done with angiographic guidance (Goldberg, Colombo, Nakamura, Almagor, Maiello, & Tobis, 1994), (Serruys & Di Mario, 1995), (Colombo, et al., 1995), (Spanos, Stankovic, Tobis, & Colombo, 2003). In other words, IVUS taught us how to implant a stent but then it failed to become the technique to be used for routine guidance.
The last two decades were characterized by the growth of new technical solutions to improve percutaneous coronary intervention. Stents are nowadays capable of eluting drugs or exerting an anti-thrombotic action due to specific coverage. Other new concepts are being investigated; for instance bioabsorbable stents capable of eluting drugs may have a role in the next future.
Since the clinical introduction of IVUS, new imaging modalities came out, with optical coherence tomography (OCT) being the most promising to improve results of interventional cardiology.
OCT is an optical analogue of IVUS, based on infra-red light emission. In comparison with IVUS, OCT has improved resolution (10 mm) and contrast and a limited penetration that does not exceed 1.3 mm, offering therefore a high resolution superficial picture of coronary arteries. This feature of OCT allows the visualization of specific components of the atherosclerotic plaques and details the architecture of stented segments, providing information similar to histology (Tanigawa, Barlis, & Di Mario, 2007), (Jang, et al., 2005), (Prati, et al., 2010), (Guagliumi & Sirbu, 2008).