Post-Procedural Angiography-Based Physiological Indices and Clinical Outcomes After Drug-Coated Balloon Treatment of In-Stent Restenosis

Drug-coated balloons (DCBs) represent an accepted approach for in-stent restenosis (ISR); however, post-procedural predictors for risk stratification remain limited. Angiography-based physiological parameters, including quantitative flow ratio (QFR), microvascular QFR (μQFR), and coronary angiography-derived fractional flow reserve (caFFR), enable noninvasive functional assessment, but their clinical implications after DCB intervention for ISR are not well established. A comprehensive literature search of PubMed, Embase, and the Cochrane Library from inception to May 2026 was conducted to identify studies evaluating post-procedural angiography-based physiological parameters in ISR patients treated with DCB. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects models, and heterogeneity was assessed using the I2 statistic. Five studies comprising 1702 patients were included. Mean age ranged from 59 to 75 years, with 75-78% males. Patients with lower post-procedural physiological index values had a significantly higher risk of vessel-oriented composite outcomes (a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization) compared with those with higher values (28.0% vs 10.3%; RR 4.65, 95% CI 1.67-12.91; P = 0.014; 5 studies). Similarly, target vessel revascularization was more frequent in the lower-value group (28.8% vs 7.5%; RR 4.88, 95% CI 1.26-18.91; P = 0.034; 4 studies). No significant associations were observed for myocardial infarction, target lesion revascularization, or cardiovascular death. Post-procedural angiography-derived physiological indices provide important prognostic information after DCB treatment for ISR. Lower values are associated with an increased risk of adverse clinical outcomes, supporting their role in risk stratification.