What makes it stentless? Development and internal validation of bailout risk score in DCB-only PCI

Background Drug-coated balloon (DCB)–only percutaneous coronary intervention (PCI) has emerged as a valid stentless strategy for de novo coronary lesions. However, the need for unplanned stent implantation ("bail-out stenting") remains a procedural challenge. No dedicated bedside tool is currently available to predict this event. Objective To develop and internally validate a simple bedside Bail-Out Risk Score predicting unplanned stent implantation during DCB-only PCI. Methods A total of 299 patients (311 de novo lesions) treated with DCB-only PCI between November 2020 and February 2025 were retrospectively analyzed. Independent predictors of bail-out stenting were identified through univariate analysis, and variables with p < 0.10 were entered into a multivariable logistic regression model. Regression coefficients were then transformed into integer points using the Sullivan method. Model performance was evaluated by AUC-ROC, calibration, and bootstrap internal validation (B = 1000). Results Bail-out stenting occurred in 17.0% of lesions (53/311). Independent predictors of bail-out stenting were prior CABG (OR 4.04, p = 0.006), proximal lesion location (OR 2.87, p = 0.013), and diffuse disease (OR 2.24, p = 0.037). Prior PCI (OR 0.46, p = 0.021) and lipid-lowering therapy (OR 0.40, p = 0.030) were protective, while LAD involvement showed a borderline association (OR 1.83, p = 0.061). The model demonstrated moderate discrimination (AUC = 0.731; optimism-corrected AUC = 0.699) and excellent calibration (intercept = 0.000, slope = 1.000). The final score (range –2 to +5) stratified lesions into low (≤–1), intermediate (0–2), and high (≥3) risk groups, with progressively higher predicted probabilities (≤22%, 38–74%, ≥86%). Conclusions The Bail-Out Risk Score, derived from six clinical and angiographic variables, provides a practical and reliable bedside tool to estimate procedural risk during stentless PCI.