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

Cardiopulmonary exercise test . (CPET) is a crucial tool for the functional evaluation of cardiac patients. We hypothesized that maximal oxygen consumption ((V) over dotO(2max)) and ventilatory efficiency-minute ventilation to carbon dioxide production ((V) over dot(E)/(V) over dotCO(2)) slope are not the only parameters of CPET able to predict major cardiac events (mortality or cardiac transplantation urgently or elective). 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. 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 analyses 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. Thirty-nine patients (27.9%) died or underwent cardiac transplantation over a median follow-up of 48 mo. Five parameters (maximal workload, breathing reserve, left ventricular ejection fraction, diastolic dysfunction, and nonidiopathic cardiomyopathy) were used to generate a risk score that had better risk discrimination than the New York Heart Association dyspnea scale, (V) over dotO(2max), (V) over dot(E)/(V) over dotCO(2 )slope > 35 alone, and combined(V) over dotO(2max) and (V) over dot(E)/(V) over dotCO(2) slope (P = 0.009, 0.004, <0.001, and 0.005, respectively) in predicting major cardiac events. A composite score of CPET and clinical/echocardiographic data is more reliable than the single use of (V) over dotO(2max) or combined with (V) over dot(E)/(V) over dotCO(2) slope to predict major cardiac events. NEW & NOTEWORTHY This is a cohort study with a follow-up of maximum of 8 years of patients with chronic heart failure that demonstrates a simple integrated score consisting of CPET (breathing reserve, workload at maximal exercise), echocardiographic (LVEF, diastolic dysfunction), and clinical (etiology of cardiac disease) data. The . generated score was a better predictor of major cardiac events (mortality or cardiac transplantation) than Weber classification ((V) over dotO(2max) classification) or NYHA functional class as single factors.