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 patient-oriented composite endpoint (POCE), defined as a composite endpoint of all-cause mortality, any stroke, any myocardial infarction, or any revascularization.During a median follow-up of 630 (IQR: 397–886) days, 147 ISR patients underwent OCT-guided DCB angioplasty, resulting in POCE development in 20 patients. At the post-procedural DCB angioplasty, the vessel-level QFR was significantly lower in the POCE group(0.88 [IQR:0.87, 0.90] vs 0.93 [IQR: 0.91, 0.95]; P < 0.001) than in the non-POCE group. Analysis of the qualitative characteristics of ISR lesions showed a significantly higher incidence of heterogeneous neointima in the POCE group compared with the non-POCE group (10 [50.00%] vs 12 [9.45%]; P < 0.001). In the multivariable Cox regression analysis, low vessel-level QFR (HR per 0.1 increase: 0.11; 95% CI: 0.03–0.39;P < 0.001) and heterogeneous neointima were independently associated with POCE. The POCE rate of vessels with the 2 features was 17.94 times higher than that of all other vessels (95%CI [2.91–110.6]; log-rank P < 0.001). Vessel-level QFR and heterogeneous neointima were independent factors associated with POCE in ISR patients after DCB angioplasty. Adding the QFR measure-ment to OCT findings may enable better discrimination of patients with subsequent POCE post-DCB angioplasty for ISR.