A Risk Score Without a Window: The Clinical Timing Problem of ORBI (Observatoire Régional Breton sur l’Infarctus) Risk Score

Introduction Cardiogenic shock (CS) is a main cause of mortality in ST-elevation myocardial infarction (STEMI). The ORBI risk score estimates in-hospital CS risk using pre- and post-procedural angiographic variables. The study aimed to prospectively validate the ORBI risk score for predicting in-hospital CS and to assess its ability to identify post-procedural CS, when all score components are available. Methods Consecutive adult STEMI patients without CS at admission were prospectively registered at a tertiary hospital during 2022-2025. Discrimination and calibration were evaluated in all patients and among patients with post-procedural CS after leaving the catheterization laboratory. Results Among 2,713 adult patients (median age 64 years; 24% female), the median ORBI score was 4 (IQR 2-7), and 103 patients (3.8%) developed in-hospital CS. Among all patients, 80% were low-risk (ORBI ≤7) with 1.0% developing in-hospital CS; 13% were low-to-intermediate risk (ORBI 8-10) with 5.6% developing CS; 3.1% were intermediate-to-high risk (ORBI 11-12) with 23% developing CS; and 3.9% were high-risk (ORBI ≥13), of whom 40% developed in-hospital CS. The score demonstrated strong discrimination (area under the receiver operating characteristic curve (AUC) 0.89; 95%CI 0.87-0.94) for in-hospital CS and for post-procedural CS (AUC 0.87; 95%CI 0.83-0.95). In patients with in-hospital CS, 68% developed peri-procedural CS. Among patients with post-procedural CS the score substantially overestimated CS risk. Conclusions The ORBI risk score performed well at predicting in-hospital CS but markedly overestimated post-procedural CS risk. As post-procedural CS is the clinically relevant endpoint for a model incorporating post-procedural variables, the ORBI score requires recalibration before it can be used to guide post-PCI decisions.