Isocapnic buffering period: From physiology to clinics

• Published in: European journal of preventive cardiology Vol. 26; no. 10; p. 1107
• Main Authors: Carriere, Cosimo, Corrà, Ugo, Piepoli, Massimo, Bonomi, Alice, Salvioni, Elisabetta, Binno, Simone, Magini, Alessandra, Sciomer, Susanna, Pezzuto, Beatrice, Gentile, Piero, Schina, Mauro, Sinagra, Gianfranco, Agostoni, Piergiuseppe
• Format: Journal Article
• Language: English
• Published: England 01.07.2019
• Subjects: Heart failure; isocapnic buffering period; exercise; anaerobic threshold
• ISSN: 2047-4881
• DOI: 10.1177/2047487319829950

During cardiopulmonary exercise test, the isocapnic buffering period ranges between anaerobic threshold (AT) and respiratory compensation point (RCP). We investigated whether oxygen uptake (VO ) increase during the isocapnic buffering period (ΔVO AT-RCP) is related to heart failure severity and prognosis. 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 ΔVO AT-RCP (below and above the median of ΔVO AT-RCP). 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 VO 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 ΔVO AT-RCP (3.85 mL/min per kg (25-75th interquartile range = 2.69-5.46)). ΔVO AT-RCP correlated with several parameters associated to heart failure prognosis, such as peak VO , VE/VCO slope, brain natriuretic peptide and left ventricular ejection fraction. The ΔVO AT-RCP value was associated with prognosis at univariate but not at multivariable analysis, where only VE/VCO slope endured. ΔVO AT-RCP correlates with several parameters linked to heart failure severity. Isocapnic buffering period stratifies heart failure patients, but not more than other prognostic indices.