Background The acute heart failure index (AHFI) is a previously derived prediction rule to identify patients presenting to emergency departments (ED) with decompensated heart failure (DHF) at low risk of early life-threatening events.

Study objectives To validate the AHFI prospectively.

Methods Using a prospective cohort study, adult patients presenting to an urban university hospital ED with DHF were included. Data on 21 variables were gathered to calculate the AHFI. Primary endpoints included inpatient death and non-fatal serious outcomes (myocardial infarction, ventricular fibrillation, cardiogenic shock, cardiac arrest, intubation, or cardiac reperfusion). Secondary endpoints included death from any cause or readmission for heart failure within 30 days. Primary and secondary endpoint rates were calculated with 95% CI for the low and higher-risk subgroups.

Results 259 patients were enrolled. 245/259 (95%) were admitted. 60/259 (23%) met low-risk criteria, of whom 1/60 (1.7%, CI 0.04 to 8.9) was discharged after sustaining pulseless electrical activity arrest. The comparable primary outcome rate in the derivation study was 1.4% (CI 1.1 to 1.7). 17/199 (8.5%, CI 5.1 to 13.3) higher-risk patients experienced an endpoint, compared with 13.3% (CI 12.9 to 13.7) in the derivation cohort. One low-risk patient (1.7%, CI 0.04 to 8.9) died within 30 days, and five (8.3%, CI 2.8 to 18.4) were readmitted. Corresponding rates in the derivation study were 2% and 5%, respectively.

Conclusion The results are consistent with those previously reported for the low-risk subgroup of the AHFI. Further research is needed to determine the impact, safety and full range of generalisability of the AHFI as an adjunct to decision making.