Natural consequence of post-intervention stent malapposition, thrombus, tissue prolapse, and dissection assessed by optical coherence tomography at mid-term follow-up

Abstract

Aims: We performed this study to clarify natural consequences of abnormal structures (stent malapposition, thrombus, tissue prolapse, and stent edge dissection) after percutaneous coronary intervention (PCI).

Methods and results: Thirty-five patients treated with 40 drug-eluting stents underwent serial optical coherence tomography (OCT) imaging immediately after PCI and at the 8-month follow-up. Among a total of 73 929 struts in every frame, 431 struts (26 stents) showed malapposition immediately after PCI. Among these, 49 remained malapposed at the follow-up examination. The mean distance between the strut and vessel wall (S-V distance) of persistent malapposed struts on post-stenting OCT images was significantly longer than that of resolved malapposed struts (342 ± 99 vs. 210 ± 49 μm; P <0.01). Based on receiver-operating characteristic curve analysis, an S-V distance ≤260 µm on post-stenting OCT images was the corresponding cut-off point for resolved malapposed struts (sensitivity: 89.3%, specificity: 83.7%, area under the curve = 0.884). Additionally, 108 newly appearing malapposed struts were observed on follow-up OCT, probably due to thrombus dissolution or plaque regression. Thrombus was observed in 15 stents post-PCI. Serial OCT analysis revealed persistent thrombus in 1 stent, resolved thrombus in 14 stents, and late-acquired thrombus in 8 stents. Tissue prolapse observed in 38 stents had disappeared at the follow-up. All eight stent edge dissections were repaired at the follow-up.

Conclusion: Most cases of stent malapposition with a short S-V distance, thrombus, tissue prolapse, or minor stent edge dissection improved during the follow-up. These OCT-detected minor abnormalities may not require additional treatment.

Keywords: Optical coherence tomography; Stent edge dissection; Stent malapposition; Thrombus; Tissue prolapse.

Figure 1

Representative OCT images: (A) classification of malapposed struts: (a) resolved malapposition, (b) persistent malapposition, (c) late-acquired malapposition, (B) classification of thrombus: (a) resolved thrombus, (b) persistent thrombus, (c) late-acquired thrombus, (C) tissue prolapse, (D) edge dissection.

Figure 2

Number of abnormal findings after stenting: (A) stent malapposition, (B) thrombus, (C) tissue prolapse, (D) edge dissection.

Figure 3

The frequency of neointimal coverage and the measurement of neointimal thickness between resolved malapposed struts, persistent malapposed struts, and late-acquired malapposed struts: (A) the incidence of struts without neointima was significantly higher in late-acquired and persistent malapposed struts compared with resolved malapposed struts. (B) The mean neointimal thickness of resolved malapposed struts was significantly thicker than that of the persistent and late-acquired malapposed struts.

Figure 4

ROC curve analysis and distribution of S–V distance of post-procedural malapposed struts. (A) An S–V distance ≤260 µm was the corresponding cut-off point for a resolved malapposed strut with a maximum sensitivity of 89.3% and a specificity of 83.7% (AUC = 0.884, P = 0.001). (B) Only eight struts with an S–V distance ≤260 μm persisted.

Figure 5

A case of persistent malapposed struts with a baseline S–V distance ≤260 μm: left panel shows the OCT image immediately after Taxus Liberte™ implantation. The S–V distance is 180 μm, which is less than the cut-off value of the S–V distance of 260 μm. These malapposed struts persisted on follow-up OCT images (right panel), probably due to plaque regression or thrombus dissolution.

Figure 6

Comparison of ROC curve analysis and distribution of S–V distance between SES and PES: (A) SES; an S–V distance of ≤280 was the best cut-off point for a resolved malapposed strut with a maximum sensitivity of 95.0% and a specificity of 100% (AUC: 0.991). All the malapposed struts with an S–V distance ≤280 μm changed to be well-apposed. (B) PES; an S–V distance of ≤260 was the best cut-off point for a resolved malapposed strut (sensitivity 87.8%, specificity 80.0%, AUC = 0.865). Eight malapposed struts with S–V distance ≤260 μm persisted.

Figure 7

A representative case of thrombus with late stent malapposition.