Mechanisms of postintervention and nine-month luminal enlargement after treatment of drug-eluting in-stent restenosis with a drug-eluting balloon

Using optical coherence tomography (OCT), the mechanisms of postintervention and 9-month luminal enlargement in drug-eluting stent in-stent restenosis (ISR) lesions treated with a drug-eluting balloon (DEB) were evaluated. A total of 42 patients with DEB-treated drug-eluting stent ISR lesions underwent serial OCT examination before intervention, after intervention, and at 9-month follow-up. Preintervention OCT-derived neointima was classified as either a homogeneous or nonhomogeneous pattern. Ten ISR lesions with homogeneous neointima were identified and compared with 32 ISR lesions with nonhomogeneous neointima. When comparing pre- and postintervention evaluations, changes in luminal cross-sectional area (CSA) were 3.4 mm ² in ISR lesions with homogeneous neointima and 3.7 mm² in those with nonhomogeneous neointima, respectively (p = 0.529); changes in stent CSA were 2.5 mm² and 1.4 mm², respectively, p = 0.004; and changes in neointimal CSA were -0.9 mm² and -2.3 mm², respectively, p = 0.001. At 9-month follow-up, changes in luminal CSA were -2.0 mm² and -0.9 mm² in ISR lesions with homogeneous and nonhomogeneous neointima, respectively (p = 0.021); in stent CSA changed by -0.2 mm² in both groups (p = 0.851) and changes in neointimal CSA was 1.8 mm² and 0.7 mm², respectively (p = 0.003). At the 9-month follow-up, >50% neointimal CSA stenosis was observed in 60% and 19% of the ISR lesions with homogeneous and nonhomogeneous neointima, respectively (p = 0.020). In conclusion, the mechanism of postintervention luminal enlargement by DEB varied with the preintervention OCT-based neointimal characteristics. ISR lesions with homogeneous neointima determined by OCT were associated with greater subsequent regrowth of neointima after DEB treatment.