Novel Scoring System Using Cardiopulmonary Exercise Testing Predicts Prognosis in Heart Failure Patients Receiving Guideline-Directed Medical Therapy

BACKGROUND: Among variables obtained from cardiopulmonary exercise testing (CPXT), peak oxygen consumption (PV̇O2) and the minute ventilation vs. carbon dioxide output (V̇E vs. V̇CO2) slope were established as predictors of death of patients with heart failure (HF) at the cutoff points of 14 ml·min(-1)·kg(-1)and 34, respectively. However, a recent update of guideline-directed medical treatment (GDMT) might alter the implication of these variables. METHODS AND RESULTS: We enrolled 77 HF patients receiving GDMT who had undergone symptom-limited CPXT between 2006 and 2014. Among them, 29 patients were re-hospitalized for HF and there were 13 cardiac deaths during the 4-year study period. Cox regression analyses demonstrated that the V̇E vs. V̇CO2slope, peak heart rate, peak systolic blood pressure, and PV̇O2were significant predictors of both re-admission and cardiac death at each cutoff point calculated by receiver-operating characteristic analyses. A new scoring system was constructed using the following criteria: 1 point was assigned to a variable meeting the cutoff point for re-admission; 2 points were assigned to that for cardiac death. The total scores calculated as the summation of each point (range, 0-8 points) had significantly highest area under the curves compared with each CPXT variable (P<0.05), and significantly stratified both event-free rate into 3 groups (P<0.05). CONCLUSIONS: A novel scoring system using 4 CPXT variables simultaneously predicted re-admission and cardiac death even in patients with HF receiving GDMT.