Prognostic implications of quantitative flow ratio and optical coherence tomography-guided neointimal characteristics in drug-coated balloon treatment for in-stent restenosis

The aim of this study was to investigate the relationship between quantitative flow ratio (QFR) after drug-coated balloon (DCB) treatment for in-stent restenosis (ISR) and between neointimal characteristics assessed by optical coherence tomography (OCT) and clinical outcomes. This single-center, retrospective, observational cohort study included ISR patients who underwent DCB angioplasty under OCT guidance. The primary outcome of the study was a target vessel failure (TVF), defined as a composite endpoint of cardiovascular death, target vessel myocardial infarction and target vessel revascularization. During a median follow-up of 756 days (IQR: 443.25, 1134.50), 204 ISR patients underwent OCT-guided DCB angioplasty, resulting in TVF development in 27 patients. At the post-procedural DCB angioplasty, the vessel-level QFR was significantly lower in the TVF group (0.89 [IQR: 0.87, 0.93] vs. 0.93 [IQR: 0.91, 0.96]; P < 0.001) than in the non-TVF group. Analysis of the qualitative characteristics of ISR lesions showed a significantly higher incidence of heterogeneous neointima in the TVF group compared with the non-TVF group (13 [48.15%] vs. 32 [18.08%]; P < 0.001). In the multivariable Cox regression analysis, low vessel-level QFR (HR per 0.1 increase: 0.11; 95% CI: 0.03-0.41; P < 0.001) and heterogeneous neointima were independently associated with TVF. The TVF rate of vessels with the 2 features was 10.69 times higher than that of all other vessels (95%CI [2.05-55.79]; log-rank P < 0.0001). Vessel-level QFR and heterogeneous neointima were independent factors associated with TVF in ISR patients after DCB angioplasty. Adding the QFR measure-ment to OCT findings may enable better discrimination of patients with subsequent TVF post-DCB angioplasty for ISR.