Optical Coherence Tomography Illuminates Intravascular Ultrasound-Invisible Sac-Like Structure After Stent Implantation

We performed a percutaneous coronary intervention (PCI) in a 79-year-old male for effort-induced angina. Coronary angiography (CAG) had revealed a diffuse lesion in the right coronary artery (RCA) (Figure A). Preprocedural intravascular ultrasound (IVUS) (OptiCross, Boston Scientific, Marlborough, MA, USA) showed eccentric and fibrofatty plaque (Supplementary Movie 1). After preparing the lesion by balloon angioplasty, a Resolute Onyx stent (4.0×26 mm; Medtronic, Santa Rosa, CA, USA) was implanted in the proximal RCA (Figure B). After Synergy stents (3.0×38 mm and 3.5×28 mm; Boston Scientific) were implanted in the mid-RCA (Figure C), we observed a slit transparent image between stents on angiography (Figure D), and the patient developed chest pain with ST elevation in ECG II, III, and aVF leads. CAG revealed slow flow in the RCA (Figure E). IVUS did not have adequate resolution to detect the cause of the slow flow (Figure F, Supplementary Movie 2), but optical coherence tomography (OCT) was able to visualize a sac-like structure impeding blood flow in the RCA (Figure G, Supplementary Movie 3). After implantation of an additional Synergy stent (3.0×16 mm) to deflate the sac-like structure, the coronary blood flow improved, and the ECG normalized. The chest pain completely disappeared.

Figure.

(A) Preprocedural angiography. Stent implanted in (B) the proximal RCA and (C) the mid-RCA. (D) The slit transparent image. (E) RCA showing slow flow. (F,G) Comparison of IVUS and OCT. (H-a–d) Plausible mechanism of flow deterioration in the present case. IVUS, intravascular ultrasound; OCT, optical coherence tomography; RCA, right coronary artery.

Discussion

We observed unexpected slow flow after stent implantation. Because it has been reported that in-stent neointimal dissection was observed by optical frequency domain imaging (OFDI) to cause a flow limitation,¹ we used OCT to successfully visualize an unusual sac-like structure that had not been detected by IVUS. Although IVUS is the established intravascular imaging modality for pre- and post-procedural lesion evaluation, it could not visualize the sac-like structure because its wall thickness was 50 μm, which is below the IVUS detection limit. The axial resolution of OCT ranges from ≈10 to 20 μm, which is approximately 10-fold higher than that of IVUS.²

We propose the following mechanism as the cause for the sac-like structure (Figure H). An intimal flap made by distal edge dissection due to the first proximal stenting (Figure H-a) moved proximally after withdrawal of the balloon used for distal lesion preparation and stenting (Figure H-b,c). This peeled vascular intima was then fixed by the distal stents and inverted into the vessel, which limited the coronary flow (Figure H-d).

Supplementary Files

Supplementary Movie 1.

Supplementary Movie 2.

Supplementary Movie 3.

Please find supplementary file(s);

http://dx.doi.org/10.1253/circj.CJ-21-0039

References

• 1.   Higaki T, Tomomori S, Dai K, Oi K, Kawase T, Suenari K, et al. Left main trunk occlusion caused by in-stent neointimal dissection. JACC Cardiovasc Interv 2020; 13: e175–e176.
• 2.   Bezerra HG, Costa MA, Guagliumi G, Rollins AM, Simon DI. Intracoronary optical coherence tomography: A comprehensive review clinical and research applications. JACC Cardiovasc Interv 2009; 2: 1035–1046.