Serial changes of minimal stent malapposition not detected by intravascular ultrasound: follow-up optical coherence tomography study

Abstract

Morphologic changes of small-sized post-stent malapposition have not been sufficiently evaluated. We investigated serial changes of minimal post-stent malapposition with a follow-up optical coherence tomography (OCT) study. Post-stent OCT and intravascular ultrasound (IVUS) and follow-up OCT were performed in 26 patients with minimal post-stent malapposition. Serial changes of number and percent of malapposition struts, and mean extra-stent malapposition area were measured in OCT analysis. Zotarolimus-eluting stent (ZES), sirolimus-eluting stent (SES), and paclitaxel-eluting stent (PES) were deployed in 17, 7 and 2 patients, respectively. Mean durations of the follow-up OCT study were 5.7 ± 3.0 months. The minimal post-stent malapposition cannot be detected by the IVUS, but be visualized with an OCT examination. According to different drug-eluting stents, malapposed stent struts were defined as the struts with detachment from the vessel wall ≥160 μm for SES, ≥130 μm for PES, and ≥110 μm for ZES. The percent of malapposition struts significantly decreased from 12.2 ± 11.0% post-stent to 1.0 ± 2.2% follow-up (P < 0.001). There was a significant decrease in the mean extra-stent malapposition area from 0.35 ± 0.16 mm(2) post-stent to 0.04 ± 0.11 mm(2) follow-up (P < 0.001). Complete disappearance of stent malapposition was also observed in 22 (85%) patients. In conclusion, minimal stent malapposition which is not detectable by IVUS may disappear or decrease in follow-up OCT evaluation.

Incidences, Predictors, and Clinical Outcomes of Acute and Late Stent Malapposition Detected by Optical Coherence Tomography After Drug-Eluting Stent Implantation

“…A previous study comparing poststent OCT with IVUS showed that minimal acute stent malapposition was detected by OCT in 62% of patients but was not detected by IVUS. 16 Lesion characteristics, such as calcification and severe diameter stenosis, were identified as predictors of acute stent malapposition. Heavily calcified lesions are known to preclude stent apposition, despite highpressure balloon dilation or rotational atherectomy.…”

Vascular Tissue Reaction to Acute Malapposition in Human Coronary Arteries

“…The neointimal healing process after stenting might spontaneously correct ISA to some extent, integrating the malapposed regions into the vessel wall, as suggested by sequential quantitative studies with optical coherence tomography (OCT), which reported ISA volumes and percentage of ISA struts decreasing over time. [1][2][3][4] Other qualitative OCT studies have also speculated about some morphological patterns at follow-up and the hypothesis that they could represent the vascular response to acutely malapposed struts. 5 The reasons why the vascular biology succeeds in covering and even integrating some ISA regions into the vessel wall but not others remain poorly understood.…”

“…Nevertheless, regions of minimal acute ISA size appear frequently covered and even totally integrated in the vessel wall at follow-up. 2,3 Thus, the question of what degree of acute ISA is worth correcting remains unanswered for the interventional cardiologist.…”

Early Stent Evaluation

“…The percent of malapposed struts signifi cantly decreased from 12.2 ± 11.0 % post-stent to 1.0 ± 2.2 % at the 6-month followup (P < 0.001). In those lesions with minimal malapposition, there was a signifi cant decrease in the mean extra-stent malapposition area from 0.35 ± 0.16 mm 2 post-stent to 0.04 ± 0.11 mm 2 at follow-up (P < 0.001) [ 38 ]. On the other hand, there are persistent malappositions and newly developed late stent malappositions detected at followup.…”