Cosimo Carriere1, Ugo Corrà2, Massimo Piepoli3, Alice Bonomi4, Elisabetta Salvioni4, Simone Binno3, Alessandra Magini4, Susanna Sciomer5, Beatrice Pezzuto4, Piero Gentile1, Mauro Schina5, Gianfranco Sinagra1, Piergiuseppe Agostoni4,6. 1. 1 Cardiovascular Department, Azienda Sanitaria-Universitaria Integrata of Trieste, Italy. 2. 2 Divisione di Cardiologia Riabilitativa, Fondazione Salvatore Maugeri, IRCCS, Istituto Scientifico di Veruno, Italy. 3. 3 UOC Cardiologia, G. da Saliceto Hospital, Piacenza, Italy. 4. 4 Centro Cardiologico Monzino, IRCCS, Milano, Italy. 5. 5 Department of Cardiovascular, Respiratory, Anaesthesiologic, Geriatric and Nephrologic Sciences, University 'Sapienza', Roma, Italy. 6. 6 Department of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Italy.
Abstract
BACKGROUND: During cardiopulmonary exercise test, the isocapnic buffering period ranges between anaerobic threshold (AT) and respiratory compensation point (RCP). We investigated whether oxygen uptake (VO2) increase during the isocapnic buffering period (ΔVO2AT-RCP) is related to heart failure severity and prognosis. METHODS: We retrospectively analysed reduced ejection fraction heart failure patients who attained RCP at cardiopulmonary exercise test. The study endpoint was the composite of cardiovascular mortality and urgent heart transplantation/left ventricular assist device implantation. Hazard ratio was assessed to identify the increase of risk associated with ΔVO2AT-RCP (below and above the median of ΔVO2AT-RCP). RESULTS: AT and RCP were both identified in 782 (39.2%) out of 1995 reduced ejection fraction heart failure cases. Left ventricular ejection fraction and peak VO2 were 33 ± 9% and 16.5 ± 4.5 mL/kg per min (61 ± 16% of predicted value), suggesting moderate heart failure. At five years, endpoint did not vary between patients below and above the median ΔVO2AT-RCP (3.85 mL/min per kg (25-75th interquartile range = 2.69-5.46)). ΔVO2AT-RCP correlated with several parameters associated to heart failure prognosis, such as peak VO2, VE/VCO2 slope, brain natriuretic peptide and left ventricular ejection fraction. The ΔVO2AT-RCP value was associated with prognosis at univariate but not at multivariable analysis, where only VE/VCO2 slope endured. CONCLUSION: ΔVO2AT-RCP correlates with several parameters linked to heart failure severity. Isocapnic buffering period stratifies heart failure patients, but not more than other prognostic indices.
BACKGROUND: During cardiopulmonary exercise test, the isocapnic buffering period ranges between anaerobic threshold (AT) and respiratory compensation point (RCP). We investigated whether oxygen uptake (VO2) increase during the isocapnic buffering period (ΔVO2AT-RCP) is related to heart failure severity and prognosis. METHODS: We retrospectively analysed reduced ejection fraction heart failurepatients who attained RCP at cardiopulmonary exercise test. The study endpoint was the composite of cardiovascularmortality and urgent heart transplantation/left ventricular assist device implantation. Hazard ratio was assessed to identify the increase of risk associated with ΔVO2AT-RCP (below and above the median of ΔVO2AT-RCP). RESULTS: AT and RCP were both identified in 782 (39.2%) out of 1995 reduced ejection fraction heart failure cases. Left ventricular ejection fraction and peak VO2 were 33 ± 9% and 16.5 ± 4.5 mL/kg per min (61 ± 16% of predicted value), suggesting moderate heart failure. At five years, endpoint did not vary between patients below and above the median ΔVO2AT-RCP (3.85 mL/min per kg (25-75th interquartile range = 2.69-5.46)). ΔVO2AT-RCP correlated with several parameters associated to heart failure prognosis, such as peak VO2, VE/VCO2 slope, brain natriuretic peptide and left ventricular ejection fraction. The ΔVO2AT-RCP value was associated with prognosis at univariate but not at multivariable analysis, where only VE/VCO2 slope endured. CONCLUSION: ΔVO2AT-RCP correlates with several parameters linked to heart failure severity. Isocapnic buffering period stratifies heart failurepatients, but not more than other prognostic indices.
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Keywords:
Heart failure; anaerobic threshold; exercise; isocapnic buffering period