Relationship between peri-strut low intensity areas and vascular healing response after everolimus-eluting bioresorbable scaffold implantation: An optical coherence tomography study

Background: Peri-strut low intensity areas (PLIA) surrounding metallic coronary stent struts on optical coherence tomography (OCT) images have been histologically related to delayed healing and inflammation, and have been associated with neointimal proliferation. The relationship between PLIA and vascular healing response after bioresorbable scaffold (BRS) implantation remains unclear.

Methods: This study includes 38 consecutive patients (50 scaffolds) evaluated using OCT 12 months after BRS implantation. Mean and percent neointimal area were quantified. A PLIA was defined as a peri-strut region with an homogenous lower intensity appearance than the surrounding tissue on OCT images without significant signal attenuation. Cross sections were scored as follows: score 0, no PLIA; score 1, <1 quadrant; score 2, ≥1 but <2 quadrants; score 3, ≥2 quadrants but <3 quadrants; and score 4, ≥3 quadrants. Scaffolds were divided into two groups (PLIA+ and PLIA-) based on the presence or absence of any PLIA in the scaffold segment.

Results: The frequency of any PLIA within the scaffold segment was 70.0%. The median PLIA score per scaffold was 0.51 (interquartile range 0-1.07). Using both scaffold- and frame-level analysis, a significant positive correlation was observed between PLIA score and both mean and percent neointimal area. Mean and percent neointimal area were significantly higher in the PLIA+ group than in the PLIA- group (1.95±0.65mm² vs. 1.51±0.27mm², p<0.01 and 24.0±7.0% vs. 17.4±3.6%, p<0.01, respectively).

Conclusion: The presence and extent of PLIA on OCT imaging after BRS implantation appears to be significantly associated with neointimal formation.