Optical coherence tomography evaluation of in-stent restenotic lesions with visible microvessels

OBJECTIVE: We sought to evaluate the characteristics of in-stent restenosis (ISR) lesions with microvessels, detected by an optical coherence tomography (OCT). BACKGROUND: No sufficient in vivo data exist regarding microvessel characteristics in ISR lesions. METHODS: Among 78 ISR lesions (drug-eluting stent, n = 72; bare-metal stent, n = 6) in our OCT registry database, visible microvessels were detected in 21 (27%). Microvessels were defined as low backscattering structures <200 m in diameter on OCT. Clinical, angiographic, and OCT findings were compared between lesions with and without microvessels. RESULTS: Lesions with microvessels had a larger reference vessel diameter (2.90 ± 0.47 mm ² vs 2.58 ± 0.42 mm ²; P=.009) and post-stent minimum lumen diameter (2.76 ± 0.29 mm ² vs 2.54 ± 0.39 mm ²; P=.033) than those without microvessels. From OCT findings at the segment with minimal lumen cross-sectional area (CSA), neointimal hyperplasia (NIH) CSA (5.4 ± 1.7 mm ² vs 4.2 ± 2.1 mm ²; P=.024) and percent NIH CSA (NIH CSA x 100/stent CSA) were significantly greater in lesions with microvessels (79 ± 12% vs 67 ± 16%; P=.001). On multivariate analysis, reference vessel diameter (odds ratio [OR], 4.64; 95% confidence interval [CI], 1.05-20.4; P=.043) and percent NIH CSA at the segment with minimal lumen CSA (OR, 1.06; 95% CI, 1.01-1.12; P=.021) were independent predictors of microvessels. From receiver operating characteristic analysis, the cut-off values of reference vessel diameter and percent NIH CSA predicting the presence of microvessels were 3.1 mm ² and 74%, respectively. CONCLUSIONS: Visible microvessels in ISR lesions might be associated with increased vessel size and extent of NIH.