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Predicting mortality for patients with heart failure beyond oxygen consumption: a prognostic risk score.

BACKGROUND
Cardiopulmonary exercise test (CPET) is a crucial tool for the functional evaluation of cardiac patients. We hypothesized that VO2 max and VE/VCO2 slope are not the only parameters of CPET able to predict major cardiac events (mortality or cardiac transplantation urgently or elective).


OBJECTIVES
We aimed to identify the best CPET predictors of major cardiac events in patients with severe chronic heart failure and to propose an integrated score that could be applied for their prognostic evaluation.


METHODS
We evaluated 140 patients with chronic heart failure who underwent CPET between 2011 and 2019. Major cardiac events were evaluated during follow-up. Univariate and multivariate logistic regression analysis were applied to study the predictive value of different clinical, echocardiographic and CPET parameters in relation to the major cardiac events. A score was generated and c-statistic was used for the comparisons.


RESULTS
Thirty-nine patients (27.9%) died or underwent cardiac transplantation over a median follow-up of 48 months. Five parameters (maximal workload, breathing reserve, left ventricular ejection fraction, diastolic dysfunction and non-idiopathic cardiomyopathy) were used to generate a risk score that had better risk discrimination than NYHA dyspnea scale, VO2 max, VE/VCO2 slope > 35 alone, and combined VO2 max and VE/VCO2 slope (p= 0.009, 0.004, < 0.001 and 0.005 respectively) in predicting major cardiac events.


CONCLUSIONS
A composite score of CPET and clinical/echocardiographic data is more reliable than the single use of VO2max or combined with VE/VCO2 slope to predict major cardiac events.