Long-term Follow-up Optical Coherence Tomography Assessment of Primary Percutaneous Coronary Intervention for Unprotected Left Main

Abstract

Background: Elective unprotected left main (ULM) percutaneous coronary intervention (PCI) has long-term mortality rates comparable to surgical revascularization, thanks to advances in drug-eluting stent (DES) design, improved PCI techniques, and frequent use of intravascular imaging. However, urgent PCI of ULM culprit lesions remains associated with high in-hospital mortality and unfavourable long-term outcomes, including DES restenosis and stent thrombosis (ST). This analysis aimed to examine the long-term outcomes and healing of DES implanted in ULM during primary PCI using high-resolution optical coherence tomography (OCT) imaging.

Methods: A total of 15 consecutive patients undergoing long-term OCT follow-up of ULM primary PCI from a high-volume center were included in this analysis. During the index primary PCI all subjects underwent angio-guided DES implantation, and follow-up was uneventful in all but one subject who had a non-target PCI lesion. The primary endpoint was the percentage of covered, uncovered, and malappossed stent struts at long-term follow-up. Secondary endpoints included quantitative and qualitative OCT measurements. For the left main bifurcation, a separate analysis was performed for three different segments: left main (LM), polygon of confluence (POC) and distal main branch (dMB), in all cases.

Results: The average follow-up interval until OCT was 1580 ± 1260 days. Despite aorto-ostial stent protrusions in 40% of patients, optimal image quality was achieved in 93.3% of cases. There were higher rates of malapposed (11.4 ± 16.6 vs. 13.1 ± 8.3 vs. 0.3 ± 0.5%; p < 0.001) and lower rates of covered struts (81.7 ± 16.8 vs. 83.7 ± 9.2 vs. 92.4 ± 6.8%; p = 0.041) observed for the LM and POC segment compared to the dMB. Significantly malapposed stent struts (>400 μm) were less likely to be covered at follow-up, than struts with a measured strut to vessel wall distance of <400 μm (15.4 ± 21.6 vs. 24.8 ± 23.9%; p = 0.011). Neoatherosclerosis was observed in 5 (33.3%) and restenotic neointimal hyperplasia (NIH) in 2 (13.3%) patients, requiring PCI in 33.3% of patients.

Conclusions: Long-term OCT examination of DES implanted during primary PCI for culprit ULM lesions demonstrated high rates of incomplete strut coverage, late malapposition, and high subclinical DES failure rates. These negative OCT results highlight the need for image optimization strategies during primary PCI to improve DES-related long-term outcomes.

Keywords: OCT; long-term follow-up; primary PCI; stent malapposition; strut endothelization; unprotected left main.

Fig. 1.

Patient flow chart. CABG, coronary artery bypass graft; CKF, chronic kidney failure; Excl., excluded patients; FU, follow-up; LM, left main; HF, heart failure; OCT, optical coherence tomography; PCI, percutanous coronary intervention; pts, patients; TLR, target lesion revascularization.

Fig. 2.

OCT longitudinal pullback and corresponding illustration of 3 segments of anatomical differentiation. dMB, distal main branch; LM, left main; OCT, optical coherence tomography; POC, polygon of confluence.

Fig. 3.

OCT follow-up protocol. LM, left main; MLA, minimal lumen area; OCT, optical coherence tomography; PCI, percutaneous coronary intervention; FFR, fractional flow reserve.

Fig. 4.

OCT exemplary images of analysed qualitative endpoints. (A) Passage of OCT catheter (yellow asterix) outside the stent in large polygon of confluence region due to suboptimal baseline balloon proximal optimization. (B) Obstruction of side branch orifice by overhanging struts neointimal hyperplasia (yellow arrow) with measurements. (C) Longitudinal stent deformation at the level of proximal stent edge with covered floating struts (red arrow). Residual blood artefacts (white asterix) characteristic for ostial cross-sections. (D) Organized thrombi (green arrow) attached on uncovered struts belonging to metallic neocarina following T and protrusion bifurcation stenting. (E) Significant neointimal hyperplasia with minimal lumen area of 2.96 mm² within under-expanded stent (area 5.2 mm²) located at mid shaft of left main. (F) In-stent neoatherosclerosis (blue asterisk) with peri-strut low intensity area, located in distal left main with minimal lumen area 4.16 mm². OCT, optical coherence tomography.

Fig. 5.

Scatter-dot matrix showing and correlation analysis between absolute difference, reference - mean stent area, to strut coverage and malapposition.

Fig. 6.

Six consecutive OCT cross-sections illustrating impact of malapposed distance on follow-up neointimal coverage. Analysed cross-section distance 0.2 mm. (A–C) Two malapposed but completely covered struts (green triangles) with hyperplastic tissue extensions from adjacent vessel wall with maximal malapposition distance bellow 400 µm. (D) Same malapposed but partially covered struts (yellow triangles). (E,F) Same malapposed and uncovered struts with measured malapposition distance $>$400 µm (red triangles). OCT, optical coherence tomography.