Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can be used to guide and optimize coronary interventions. The European Association of Percutaneous Cardiovascular Intervention (EAPCI) produced an expert consensus document to summarize the role of intracoronary imaging in clinical practice.
Räber et al. reported on strengths and limitations of the use of IVUS and OCT in pre- and post-procedural applications. With respect to angiography, intracoronary imaging provides additional information concerning the arterial vessel wall, plaque composition and stent positioning.
Firstly, intracoronary imaging can be used for planning and optimizing stenting procedures. Guidelines and this expert consensus, especially advise the use of IVUS to guide PCI of long lesions, CTOs and ostial left-main lesions or in patients at risk of developing contrast-induced kidney injuries. IVUS and OCT are also recommended for left main lesions or complex lesions. The higher resolution of OCT allows to more accurately identify thrombi and culprit plaques in ACS patients as well as stent malapposition (lack of contact of stent struts with the vessel wall) immediately after the procedure.
With respect to angiography, intracoronary imaging provides additional information concerning the arterial vessel wall, plaque composition and stent positioning.
Secondly, the assessment of plaque composition and distribution by intravascular imaging can aid lesion preparation, stent size choice and stent positioning. Pullback recordings starting 20 mm distal to the stenosis and ending at the RCA or left main ostium are recommended for these purposes.
Increased calcium thickness (> 0.5 mm) and calcium pools with a maximum angle > 180° are associated with increased risk of stent underexpansion, which is an established predictor of stent failure due to early thrombosis and restenosis. IVUS and especially OCT are particularly valuable for detection, localization and quantification of coronary calcifications. Moreover, co-registration of intracoronary imaging and angiography allows selecting adequate stent length and precise stent placement. A distal lumen reference based sizing approach is advised, being practical and straightforward, with optimization of the mid and proximal part by subsequent post-dilatation. Criteria to assess optimal stent results require achieving a relative stent expansion of 80% in routine clinical practice with a minimum stent area (MSA) > 5.5 mm2 by IVUS and > 4.5 mm2 by OCT in non-left main lesions.
Thirdly, intracoronary imaging is highly recommended for assessing stent restenosis and stent thrombosis, in order to understand the underlying mechanism for stent failure: stent malapposition and underexpansion, residual disease burden at stent edge and dissections. OCT is the preferred technique for this purpose and specific treatment strategies can be derived accordingly.
Intracoronary imaging has a widely acknowledged value in the setting of coronary interventions. Potential limitations are additional costs and longer procedural time. However, cost-effectiveness of this approach has been shown in patients with higher risk of restenosis.
Author: Lorena Casadonte