Optical coherence tomography (OCT) has approximately 10 times higher resolution than IVUS. It can precisely measure lumen diameters in the variable geometry of a bifurcation lesion and identify superficial lipid laden plaques and calcium, relevant to confirm the severity of the lumen obstruction prior to treatment and guide location and diameter of the stent. OCT produces fewer strut-induced artifacts and offers precise evaluation of strut apposition in a real-life clinical setting. The increase in the speed of image acquisition with the introduction of frequency domain OCT allows rapid pull-back at a speed of 36 mm/sec, minimizing the amount of contrast required to clear blood during image acquisition. This enables serial OCT acquisitions, particularly before treatment if the lesion is not very severe and flow is expected to be present around the OCT catheter, after predilatation and to assess and guide stent expansion.

Repeated OCT examinations at follow-up can help in the detection of presence and characteristics of strut coverage, which can predict late stent thrombosis. These applications are of particular interest in the context of bifurcation lesion treatment as this condition is still associated with a higher number of malapposed stent struts and frequent impairment of stent expansion.

OCT can provide unique insights in the setting of bifurcation lesions by enabling detailed evaluation of coronary bifurcation pathology and facilitating procedural planning. OCT imaging has contributed enormously to the optimization of bifurcation stenting techniques. With its high resolution, OCT enables interventionlists to re-cross proper stent cell, which is the key procedure in both provisional stenting and 2-stent techniques. Poststenting OCT imaging provides unique information for further optimal treatment strategy.

OCT is a better tool as compared to angiography as it depicts ostial lesions in bifurcation without the misleading two-dimensional appearance of angiography such as overlap and foreshortening. OCT can help reconstruct a bifurcation in three dimensions and can assess the side branch ostium from 3D reconstruction of the main vessel pull-back, which can be applied to ensure optimal re-crossing position of the wire after main vessel stenting.

Its ability to provide unique information on the plaque at high risk for rupture, plaque composition, thickness of fibrous cap, the presence of macrophage and thrombi has assisted in simple PCI as well as in complex bifurcation lesions PCI.

OCT helps provide valuable anatomic information to optimize stent implantation and adapt PCI strategy in individual patients.