ABSTRACT: Stent malapposition remains an important cause of complications following stent implantation. Stent underexpansion is a frequent cause of this. We describe a case of coronary stent malapposition as a result of a post-stenotic aneurysm. Both the malapposition and its etiology were clearly demonstrated by optical coherence tomography, a novel high-resolution imaging technology.

       An 82-year-old female with exertional dyspnea and a positive stress test underwent elective coronary angiography which revealed lesions in the left anterior descending coronary artery and right coronary artery

Figure 1. Right coronary angiogram before and after stent deployment. (A) Prior to stent deployment, a severe lesion of the mid-right coronary artery is seen with post-stenotic aneurysm formation (arrow). (B) Close-up view of the position of the stent (balloon markers indicated by arrows) prior to deployment. Note the distal end of the stent within the dilated aneurysmal segment. (C) Satisfactory angiographic result following stent deployment.

(RCA). Staged percutaneous interventions were planned, beginning with the RCA lesion. The RCA lesion was a severe (90%) stenosis of the mid-portion of the vessel associated with a region of post-stenotic aneurysm formation (Figure 1A). Following predilatation with a 2.5 mm x 15 mm Quantum Maverick™ balloon (Boston Scientific Corp. Natick, Massachusetts), a Cypher™ 2.5 mm x 18 mm stent (Cordis Corp., Miami, Florida) was passed across the lesion with its distal end within the dilated post-stenotic region (Figure 1B). The stent was

Figure 2. Optical coherence tomography (OCT) images of the right coronary artery following stent deployment. (A) Image within the aneurysmal segment showing stent strut malapposition (arrows). (B) Image within the proximal stent showing satisfactory stent deployment and strut apposition. (C) L-mode image of OCT pullback clearly showing the distal aneurysmal segment. The position of stent is marked by the red horizontal line. The sites corresponding to the images in A and B are identified by the interrupted and bold vertical white lines, respectively.

deployed with balloon inflation at 14 atmospheres and postdilated using a 2.75 mm x 15 mm Quantum Maverick balloon at 15 atmospheres, yielding a satisfactory angiographic result as seen in Figure 1C. Following successful stent deployment, optical coherence tomography (OCT) imaging of the RCA was performed (LightLab Imaging Inc., Westford, Massachusetts)*. OCT imaging of the distal end of the stent within the aneurysmal segment clearly demonstrated inadequate stent strut apposition against the vessel wall (Figure 2A). The rest of the stented segment showed good stent apposition (Figure 2B).

       Conclusion. Stent malapposition remains an important cause of complications, including stent thrombosis following stent implantation.1,2 Stent underexpansion is a frequent cause of this. In this patient, however, positioning of the distal end of the stent within the aneurysmal segment distal to the stenosis resulted in localized strut malapposition, despite postdilatation of the deployed stent with an oversized balloon and good stent expansion over the rest of the stented segment. OCT imaging in this case provided detailed information of the stented region, enabling both the detection of the malapposition and its cause.