Utility of shock index to predict mortality risk in decompensated heart failure

Abstract

Background: Decompensated heart failure (HF) is a serious condition that requires rapid evaluation and treatment. Shock index (SI) is a bedside predictor tool used to identify risk of mortality and morbidity.

Methods: This multicentre retrospective descriptive study evaluated SI, modified shock index (MSI) and reverse shock index (RSI) as predictors of mortality in decompensated HF. Emergency department records for a 6-month period were analysed. The primary outcome was to identify if SI > 0.9 could predict mortality during hospital admission. Secondary outcomes included SI > 0.9, MSI > 0.93 and RSI < 1 for prediction of 72-h mortality, use of non-invasive positive pressure ventilation, inotropic, vasopressor or nitroglycerine infusions and need for endotracheal intubation.

Results: Overall mortality during hospital admission was 4.3%, impacting internal validity. For inotrope use, SI > 0.9 at 12 h produced an odds ratio (OR) of 12.33 (confidence interval [CI] 2.03–74.89; P 0.006). Modified shock index > 0.93 suggested potential for mortality and critical intervention prediction but lacked statistical significance. Reverse shock index < 1.0 at 0 h indicated ORs of 8.89 (CI 1.11–70.98) for in-hospital mortality and 9.88 (CI 1.70 – 57.27) for inotrope use.

Conclusion: SI > 0.9 at 12 h predicted an increased need for inotropes. Reverse shock index demonstrates significant predictive value for mortality and critical interventions in decompensated HF. Reverse shock index appears to be the most effective index in predicting both mortality and need for critical interventions, outperforming SI and MSI. Further prospective studies are needed to validate these findings.

Contribution: This research will assist with early triage of decompensated HF patients to appropriate dispositions and guide inexperienced clinicians to identify high-risk patients.