Excimer Laser Coronary Angioplasty for In-stent Restenosis: Impact of Tissue Characteristics Assessed by Optical Coherence Tomography on Acute and Mid-term Results

Background: Recently, excimer laser coronary angioplasty (ELCA) with angiographic or IVUS guidance failed to show its superiority over the conventional balloon angioplasty for treating ISR. We evaluated the clinical significance of OCT in ELCA for ISR.
Methods: Between April 2014 and October 2016, 53 ISR lesions were treated with ELCA catheter. After ECLA ablation, additional balloon dilatation with either scoring balloon or non-compliant balloon was conducted. Procedure was finalized with application of drug-coated balloon. During PCI procedure, tissue characterization and lumen measurement with OCT was performed three times: 1) before PCI, 2) after ablation with ELCA and 3) at the end of procedure. Based on the initial OCT findings, the lesions were categorized into the 3 groups: 1) homogenous, 2) layered and 3) mixed group. For each lesion, follow-up angiogram (without OCT) was conducted 6-12 months after PCI.
Results: The lesions were categorized into 20 homogenous, 21 layered and 12 mixed type lesions. No significant difference was observed in the initial MLA between the three groups (1.01±0.31 mm², 1.06±0.50 mm², 1.29±0.75 mm², P=0.148). After ELCA, MLA in the mixed group (2.24 ± 0.70 mm²) was larger than in the homogeneous group (1.75±0.84 mm², P=0.119) and the layered group (1.72±0.45 mm², P=0.044). Final MLA in the mixed group (5.49±1.45 mm²) was larger than in the homogeneous group (4.03±1.46 mm², p=0.014) and the layered group (4.92±1.79 mm², P=0.376). The follow-up angiogram revealed no significant difference in terms of ISR rate (homogeneous 55.5%, layered 33.3%, mixed 33.3%; P=0.300) and TLR rate (TLR: homogeneous 30.0%, layered 23.8%, mixed 25.0%; P=0.896).
Conclusions: In treatment for ISR, effectiveness of ELCA in acute phase depends upon the tissue characteristics detected by OCT. Despite these difference observed in acute phase, no difference was observed in ISR and TLR rate after 6-12 month.