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Lumped-Parameter and Finite Element Modeling of Heart Failure with Preserved Ejection Fraction
Published on: February 13, 2021
Development of a composite model derived from cardiopulmonary exercise tests to predict mortality risk in patients
Lee Ingle1, Alan S Rigby, Rebecca Sloan
1Department of Sport, Health & Exercise Science, University of Hull, , Kingston-upon-Hull, UK.
Insights
A new composite risk score using cardiopulmonary exercise testing (CPET) variables better predicts mortality in heart failure (HF) patients than single variables. This CPET risk score improves outcome prediction for mild-to-moderate HF.
Area of Science:
- Cardiology
- Exercise Physiology
- Prognostic Biomarkers
Background:
- Cardiopulmonary exercise testing (CPET) is crucial for predicting outcomes in patients with mild-to-moderate heart failure (HF).
- Current practice often relies on single CPET-derived variables for prognostication.
- The potential for a composite score to enhance predictive accuracy remains an area of investigation.
Purpose of the Study:
- To evaluate whether a composite risk score derived from CPET variables offers superior predictive power for mortality in mild-to-moderate HF patients compared to individual variables.
- To develop and validate a novel CPET-based risk score for outcome prediction in this patient cohort.
Main Methods:
- Retrospective analysis of 387 mild-to-moderate heart failure patients who underwent symptom-limited maximal CPET.
- Survival models incorporating nine CPET-derived variables were built using a hybrid bootstrap and Cox regression approach.
- Z-scores quantified individual variable predictive strength, and model coefficients were used to create a composite risk score.
Main Results:
- Four CPET variables independently predicted all-cause mortality: exertional oscillatory ventilation (EOV), VE/VCO2 slope, oxygen uptake efficiency slope (OUES), and VEqCO2 nadir.
- The composite Hull CPET risk score achieved a higher predictive accuracy (Harrell's C-statistic=0.75, AUC=0.78) than individual variables (C-statistic 0.60-0.71) and the HF Survival Score (AUC=0.70).
- The developed composite score demonstrated significantly better discrimination for mortality.
Conclusions:
- A composite risk score integrating multiple CPET variables significantly outperforms the traditional single-variable approach for predicting mortality in mild-to-moderate heart failure.
- The novel Hull CPET risk score offers improved prognostic capability, potentially aiding clinical decision-making and patient management.
Objective:
Cardiopulmonary exercise testing (CPET) is used to predict outcome in patients with mild-to-moderate heart failure (HF). Single CPET-derived variables are often used, but we wanted to see if a composite score achieved better predictive power.
Methods:
Retrospective analysis of patient records at the department of cardiology, Castle Hill Hospital, Kingston-upon-Hull. 387 patients (median (25th-75th percentile)) (age 65 (56-72) years; 79% men; LVEF 34 (31-37) %) were included. Patients underwent a symptom-limited, maximal CPET on a treadmill. During a median follow-up of 8.6±2.1 years in survivors, 107 patients died. Survival models were built and validated using a hybrid approach between the bootstrap and Cox regression. Nine CPET-derived variables were included. Z-score defined each variable's predictive strength. Model coefficients were converted to a risk score.
Results:
Four CPET-related variables were independent predictors of all-cause mortality in the survival model: the presence of exertional oscillatory ventilation (EOV), increasing slope of the relation between ventilation and carbon dioxide production (VE/VCO2 slope), decreasing oxygen uptake efficiency slope (OUES), and an increase in the lowest ventilatory equivalent for carbon dioxide (VEqCO2 nadir). Individual predictors of mortality ranged from 0.60 to 0.71 using Harrell's C-statistic, but the optimal combination of EOV+VE/VCO2 slope+OUES+VEqCO2 nadir reached 0.75. The Hull CPET risk score had a significantly higher area under the curve (0.78) when compared to the HF Survival Score (AUC=0.70; p<0.001).
Conclusions:
A composite risk score using variables from CPET out-performs the traditional single variable approach in predicting outcome in patients with mild-to-moderate HF.
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