Longitudinal Stent Deformation: Insights Provided by Optical Coherence Tomography

Key words: bifurcation intervention, complication, longitudinal stent deformation, optical coherence tomography, percutaneous coronary intervention, stent failure

A 60-year-old man underwent elective percutaneous coronary intervention (PCI) for stable coronary artery disease. The angiogram showed Medina 1,1,1 disease at the bifurcation of the mid left anterior descending (LAD) coronary artery and major diagonal and provisional bifurcation stenting was planned. The diagonal branch was protected with a guidewire and a 2.75 x 32 mm drug-eluting stent was implanted in the mid LAD. Proximal optimization was done using a 3 mm non-compliant (NC) balloon. The sidebranch was recrossed through the distal stent strut. During removal of the trapped sidebranch guidewire, the guide catheter was inadvertently sucked into the LAD, striking the proximal edge of the stent. The sidebranch struts were dilated with a 2.25 x 12 mm NC balloon and a deformity of the proximal end of the stent was noted. Optical coherence tomography (OCT) showed multiple layers of stent struts in the proximal portion of the stent with significant malapposition, diagnostic of longitudinal stent deformation (Figure 1). Stent-rendered imaging and three-dimensional (3D) reconstruction showed crowding of the stent struts. The proximal portion of the stent was redilated with a 3 mm NC balloon at high pressure. The final OCT image showed all stent struts well-apposed to the vessel wall with no protrusion into the lumen and good stent expansion (Figure 2).

Longitudinal stent deformation is defined as shortening or elongation of the stent along its longitudinal axis after deployment. It is under-recognized on angiography, and imaging-based studies have reported an incidence of up to 1%. The etiology includes damage by the guiding catheter or secondary devices such as postdilation balloons, imaging catheters, additional stents, or because of wire entanglement. Deformation can occur with all stent platforms. In the present case, forceful removal of the trapped guidewire led to the guide being sucked into the LAD and deforming the stent. 

Uncorrected longitudinal stent deformation increases the risk of major adverse outcomes, including stent thrombosis and in-stent restenosis. Intravascular imaging helps in the recognition of this deformity. Once recognized, longitudinal stent deformation should be corrected with high-pressure dilation using an NC balloon. If there is significant luminal obstruction or difficulty in passing the NC balloon, a low-profile, semicompliant balloon should be used first. If the stent deformity cannot be corrected, or if there is a vessel injury in the uncovered segment at the stent edge, another stent should be implanted. The result should be confirmed by intravascular imaging.