Heart Failure Scores

Heart Failure Survival Score (HFSS) Calculator

Clinical calculation support · Verify results before clinical use

Non-invasive HFSS assessment

Enter all seven clinical variables. Use measurements obtained during a stable, ambulatory heart failure assessment. Input limits are plausibility checks, not HFSS cutoffs.

—HFSS

Clinical and haemodynamic variables

1

Resting heart rate

Resting pulse rate at the time of assessment.

Continuous variable
2

Mean arterial blood pressure

Enter mean arterial pressure (MAP), not systolic or diastolic pressure.

Continuous variable
3

Left ventricular ejection fraction

Use LVEF expressed as a percentage.

Continuous variable
4

Serum sodium

Use the measured serum sodium concentration.

Continuous variable
5

Peak oxygen consumption (peak VO₂)

Measured by cardiopulmonary exercise testing (CPET); do not substitute estimated exercise capacity.

Continuous variable

Aetiology and electrocardiographic variables

6

Ischaemic heart disease aetiology

Select present if the underlying cardiomyopathy/heart failure is ischaemic in origin.

0 or 1
7

Intraventricular conduction delay (IVCD)

Select present for IVCD with QRS duration ≥120 ms (e.g. bundle branch block or ventricular-paced rhythm, as operationalised in published HFSS applications).

0 or 1

About the Heart Failure Survival Score

The Heart Failure Survival Score (HFSS) is a prognostic model developed for ambulatory patients with advanced heart failure referred for cardiac transplantation evaluation. This calculator implements the original non-invasive seven-variable model.

The original study derived the model in 268 patients and prospectively validated it in 199 similar patients. Its endpoint was death or urgent heart transplantation without transplant. The 1-year event-free survival rates in the derivation and validation samples were, respectively, 93% and 88% in the low-risk group, 72% and 60% in the medium-risk group, and 43% and 35% in the high-risk group.

Variables and coefficients

VariableCoefficientUnit / coding
Resting heart rate+0.0216beats/min
Mean arterial pressure−0.0255mmHg
LVEF−0.0464%
Serum sodium−0.0470mmol/L
Peak VO₂−0.0546mL/kg/min
IVCD+0.608Present = 1; absent = 0
Ischaemic aetiology+0.6931Present = 1; absent = 0

Formula

HFSS = absolute value of the sum:

0.0216 × resting HR − 0.0255 × mean BP − 0.0464 × LVEF − 0.0470 × serum sodium − 0.0546 × peak VO₂ + 0.608 × IVCD + 0.6931 × ischaemic aetiology.

Risk-stratum interpretation

HFSS scoreRisk stratumOriginal 1-year event-free survival*
≥8.10Low risk93% derivation; 88% validation
7.20–8.09Medium risk72% derivation; 60% validation
≤7.19High risk43% derivation; 35% validation

*Event-free survival refers to freedom from death or urgent transplantation in the original study cohorts, not a general-population survival estimate.

Clinical use and limitations

HFSS was developed in ambulatory patients with advanced chronic heart failure being evaluated for transplantation. The original model requires peak VO₂ measured by CPET; substituting a walk-test estimate or a subjective functional assessment is not validated by this calculator.

  • Use as an adjunct to comprehensive advanced heart failure assessment, not as a stand-alone decision rule.
  • Confirm that measurements represent a clinically stable assessment and use consistent units.
  • HFSS risk strata do not independently establish transplant eligibility or listing priority.
  • The original cohort predates contemporary heart failure therapies and devices; later validation supports prognostic discrimination in beta-blocker-treated cohorts, but does not remove limitations in current individual-level calibration.
  • Scores may perform less reliably in patients unlike the original ambulatory transplant-evaluation population, including those unable to perform CPET.

Guideline context

The 2024 ISHLT guideline states that adult heart failure prognosis scores may be considered alongside other data collected during transplant evaluation. Scores should not be used as the sole criterion for listing; the guideline also cautions that many scores have limited contemporary validation and perform poorly when applied to individuals.

References

Aaronson KD, Schwartz JS, Chen TM, Wong KL, Goin JE, Mancini DM. Development and prospective validation of a clinical index to predict survival in ambulatory patients referred for cardiac transplant evaluation. Circulation. 1997;95(12):2660–2667. DOI: 10.1161/01.cir.95.12.2660. PMID: 9193435.
Koelling TM, Joseph S, Aaronson KD. Heart failure survival score continues to predict clinical outcomes in patients with heart failure receiving beta-blockers. J Heart Lung Transplant. 2004;23(12):1414–1422. DOI: 10.1016/j.healun.2003.10.002. PMID: 15607672.
Peled Y, Ducharme A, Kittleson M, et al. International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates—2024. J Heart Lung Transplant. 2024. DOI: 10.1016/j.healun.2024.05.010.
Ingle L, Rigby AS, Sloan R, et al. Development of a composite model derived from cardiopulmonary exercise tests to predict mortality risk in patients with mild-to-moderate heart failure. Heart. 2014;100(10):781–786. DOI: 10.1136/heartjnl-2013-304614. This paper reports the HFSS variable definitions, IVCD operationalisation, and coefficients when using HFSS as a comparator.
Clinical disclaimer: This calculator is intended for educational and clinical decision-support use by qualified healthcare professionals. It does not replace clinical judgement, comprehensive heart failure evaluation, CPET interpretation, multidisciplinary transplant assessment, or current guideline-based care. Do not use the score alone to make transplant listing or treatment decisions.
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