The HELP Score in Non-Asphyxial Hypothermic Cardiac Arrest Treated With Extracorporeal Life Support: External Validation and Clinical Utility

Hypothermic cardiac arrest can result in a good outcome when patients are rewarmed using extracorporeal life support (ECLS), but patient selection for this treatment is challenging. The HELP score (Hemoglobin, Exposure, Lactate, Potassium) is a novel prognostic tool for estimating the survival chances of patients with non-asphyxial hypothermic cardiac arrest rewarmed with ECLS. In this retrospective multicenter study, we performed external validation of the HELP score and evaluated its clinical utility. We calculated predicted survival based on the original HELP equation and assessed overall performance, discrimination, calibration, and decision curve analysis. The study population included 106 patients from eight countries. The survival rate to hospital discharge was 65% (69/106); a favorable neurological outcome was found in 88% of survivors. The HELP score showed excellent discrimination (area under the receiver operating characteristic curve 0.80) and good overall performance (Brier 0.17). Calibration analysis showed a mild underestimation of survival (slope 0.92; intercept 0.64). Decision curve analysis showed a positive net benefit compared with a "treat all" strategy across a wide range of thresholds. The HELP score revealed excellent discrimination, good overall performance, and clinically meaningful positive net benefit in the external validation cohort. This model can be a useful aid in decisions on ECLS application in adult patients with non-asphyxia-related hypothermic cardiac arrest, but it should not replace a team-based, multidisciplinary approach.