In-stent restenosis assessed with frequency domain optical coherence tomography shows smooth coronary arterial healing process in second-generation drug-eluting stents

INTRODUCTION@#The pathophysiology and mechanism of in-stent restenosis (ISR) after implantation of second-generation drug-eluting stents (DESs) are not fully clear. We compared the morphological characteristics of ISR between first- and second-generation DESs using frequency domain optical coherence tomography (OCT).@*METHODS@#Patients who underwent follow-up coronary angiography (CAG) after first-generation (CYPHER™ and TAXUS™) and second-generation (Nobori®, PROMUS Element™, Resolute Integrity and XIENCE) DES implantations were examined. ISR was defined as lesions of over 50% diameter stenosis at follow-up CAG. Frequency domain OCT was performed at the time of revascularisation of ISR. Tissue morphology was assessed at minimum lumen area. OCT images of DESs at both early (≤ 1 year) and late (> 1 year) phase follow-up were compared.@*RESULTS@#On qualitative OCT assessment, the ratios of homogeneous, layered, heterogeneous without-attenuation and heterogeneous with-attenuation morphologies were 57.1%, 17.1%, 20.0% and 5.7%, respectively, for second-generation DES ISR (n = 35), and 16.7%, 25.0%, 25.0% and 33.3%, respectively, for first-generation DES ISR (n = 36). At late phase follow-up, homogeneous morphology was significantly more common for second-generation DES ISR compared to first-generation DES ISR (first-generation: 8.0% vs. second-generation: 50.0%; p < 0.01) while heterogeneous with-attenuation morphology was significantly more common for first-generation DES ISR (first-generation: 44.0% vs. second-generation: 5.6%; p < 0.01).@*CONCLUSION@#Homogeneous tissue morphology was more frequently found for second-generation than first-generation DES ISR, especially in the late phase. This suggested that neointimal hyperplasia was the main mechanism in second-generation DES ISR, and that the neointima was stabilised, much like in bare metal stent implantation.

The Role of Optical Coherence Tomography in Coronary Intervention

Optical coherence tomography (OCT) is an optical analog of intravascular ultrasound (IVUS) that can be used to examine the coronary arteries and has 10-fold higher resolution than IVUS. Based on polarization properties, OCT can differentiate tissue characteristics (fibrous, calcified, or lipid-rich plaque) and identify thin-cap fibroatheroma. Because of the strong attenuation of light by blood, OCT systems required the removal of blood during OCT examinations. A recently developed frequency-domain OCT system has a faster frame rate and pullback speed, making the OCT procedure more user-friendly and not requiring proximal balloon occlusion. During percutaneous coronary intervention (PCI), OCT can provide detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition [ISA]). At follow-up examinations after stent implantation, stent strut coverage and ISA can be assessed. Several OCT studies have demonstrated delayed neointimal coverage following drug-eluting stent (DES) implantation vs. bare metal stent (BMS) placement. While newer DESs promote more favorable vascular healing, the clinical implications remain unknown. Recent OCT studies have provided insights into restenotic tissue characteristics; DES restenotic morphologies differ from those with BMSs. OCT is a novel, promising imaging modality; with more in-depth assessments of its use, it may impact clinical outcomes in patients with symptomatic coronary artery disease.

Qualitative and quantitative evaluation of coronary plaques with 64-slice computed tomography in comparison with intravascular ultrasound / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the diagnostic feasibility of noninvasive assessment of coronary atherosclerotic plaques with MSCT in comparison with IVUS.</p><p><b>METHODS</b>Contrast-enhanced MSCT angiography (Sensation 64, Siemens Medical Solutions) was performed before percutaneous coronary intervention (PCI), and three-vessel IVUS (Boston Scientific, Natick, MA) was performed during procedure in 12 patients with stable angina pectoris. Complete investigation was digitally stored, and assessed offline with EchoPlaque (Indec Systems, Mountain View, CA). The comparison of MSCT with IVUS was performed based on segment at plaque site (American Heart Association 15-segment model).</p><p><b>RESULTS</b>A total of 88 segments in 31 vessels (left anterior descending: 12, left circumflex: 10, and right coronary artery: 9) were investigated by both IVUS and MSCT. Among 68 assessable segments (54 proximal-middle segments and 14 distal segments) by MSCT (20 segments were excluded for poor image quality: 16 for severe calcification, 2 for motion artifact, 2 for poor opacification), MSCT correctly detected 47 of the 51 segments with plaques (sensitivity: 92%), and correctly evaluated 16 of 17 segments without plaques (specificity: 94%). Concerning plaque quantification, MSCT correlated well with IVUS in grading whether the vessel obstruction was less or more than 50% (simple kappa: 0.63, 95% CI: from 0.47 to 0.78). Plaque area by MSCT also correlated with that by IVUS (r = 0.53, P < 0.01), but overestimated plaque area [(9.09 +/- 3.89) mm(2) vs. (6.80 +/- 2.81) mm(2), P < 0.01]. In addition, 30 of 43 hypoechoic compositions were detected as low-density compositions by MSCT with average CT number as 67.39 HU.</p><p><b>CONCLUSIONS</b>In segments without severe calcification, contrast-enhanced 64-slice CT angiography could detect plaques in coronary artery with high accuracy. Plaque area quantification by MSCT correlated with that of IVUS though with limited accuracy.</p>