Submaximal exercise parameters, including OUES (AUC 0.781, P=0.018) and V˙E/V˙CO2 slope (AUC 0.714, P=0.04), were significantly associated with 2-year cardiac morbidity in Fontan patients.
Cohort (n=52)
Do submaximal exercise parameters predict cardiac morbidity better than maximal exercise parameters in Fontan patients?
Submaximal exercise parameters, specifically OUES and V˙E/V˙CO2 slope, provide superior prognostic information compared to maximal exercise data for predicting cardiac morbidity in Fontan patients.
Effect estimate: AUC for OUES 0.781, AUC for V˙E/V˙CO2 slope 0.714
p-value: p=0.018 for OUES, 0.04 for V˙E/V˙CO2 slope
INTRODUCTION: Submaximal exercise parameters are associated with an increased risk of hospitalization in patients with heart failure, but the implication in patients with Fontan circulation remains unknown. We investigated the prognostic value of these parameters in a Fontan cohort, in whom maximal exercise effort is often limited. METHODS: Fifty-two Fontan patients received cardiopulmonary exercise tests at least 12 months after Fontan completion. We evaluated two maximal parameters (peak oxygen consumption (V˙O2) and HR reserve) and two submaximal parameters (oxygen uptake efficiency slope (OUES) and minute ventilation (V˙E) to carbon dioxide elimination (V˙CO2) slope). RESULTS: The peak V˙O2 and OUES were 58.0% ± 11.2% and 56.6% ± 14.5% of the age- and sex-related predicted values. In the subsequent follow-up (median, 22.7 months), 11 patients (21%, including one death) exhibited cardiac morbidity, defined as cardiac-related hospitalization. Time-dependent receiver operating characteristic curve analysis demonstrated that only submaximal parameters were related to 2-yr cardiac morbidity (area under the curve for OUES 0.781, P = 0.018; for V˙E/V˙CO2 slope 0.714, P = 0.04), even in the subgroup achieved maximal exercise effort. The optimal threshold value for OUES was 45%, and for the V˙E/V˙CO2 slope, it was 37. Furthermore, the OUES conveyed independent prognostic information beyond resting oxygen saturation and a history of heart failure or protein-losing enteropathy. CONCLUSION: Submaximal exercise parameters provide superior prognostic information to maximal exercise data for predicting cardiac morbidity in Fontan patients. Moreover, the association between the OUES and cardiac morbidity is independent of relevant baseline clinical information.
Chen et al. (Thu,) conducted a cohort in Fontan circulation (n=52). Submaximal exercise parameters (OUES and V˙E/V˙CO2 slope) vs. Maximal exercise parameters (peak V˙O2 and HR reserve) was evaluated on 2-yr cardiac morbidity (cardiac-related hospitalization) (AUC for OUES 0.781, AUC for V˙E/V˙CO2 slope 0.714, p=0.018 for OUES, 0.04 for V˙E/V˙CO2 slope). Submaximal exercise parameters, including OUES (AUC 0.781, P=0.018) and V˙E/V˙CO2 slope (AUC 0.714, P=0.04), were significantly associated with 2-year cardiac morbidity in Fontan patients.