In regard to the assessment of performance in cardiopulmonary exercise tests, oxygen uptake (VO2) at anaerobic threshold (AT) and respiratory compensation point (RCP) has been suggested to have a prognostic value and be a marker for heart failure (HF) severity. “Even the absence of an identifiable AT, despite the achievement of exercise-induced anaerobiosis, has a strong prognostic power,” explains Piergiuseppe Agostoni, MD, PhD. “And although VO2 at the respiratory compensation point (RCP) may carry important physiological and prognostic information, the precise definitions of VO2 at AT or RCP remain unclear.”
For a study published in CHEST, Dr. Agostoni and colleagues retrospectively analyzed data from nearly 2,000 patients with HF with reduced ejection fraction (HFrEF) to evaluate the prognostic meaning of the simple absence of identifiable AT (group 1), absence of RCP but presence of AT (group 2) and presence of both AT and RCP (group 3) during cardiopulmonary exercise tests (CPETs) performed with a maximal incremental exercise protocol.
The study authors observed 87 (30%), 169 (18%), and 111 (14%) events in groups 1, 2, and 3, respectively during a median follow-up of 2.97 years (interquartile range, 1.50-5.35 years). When compared with group 3 (patients with the best survival), the likelihood of reaching the study endpoint increased 2.7 times when neither AT nor RCP were identified (hazard ratio [HR}, 2.74) and 1.4 times when only AT was identified (HR, 1.4). “Notably, we showed that the presence/absence of identified AT and RCP has a potential prognostic role, simplifying the analysis of CPET and avoiding the need for a detailed assessment of AT and RCP, as well as of the VO2 value at AT and RCP,” notes Dr. Agostoni. “Moreover, the analysis of AT and RCP identification improves the prognostic power of peak VO2, confirming the strong physiological meaning of AT and RCP.”
The results indicate that AT and RCP identification could influence prognostic stratification of HFrEF. “Our findings could benefit clinicians if entered into routine practice and if clinicians begin to consider AT and RCP identification as important and useful data in CPETs,” adds Dr. Agostoni.
Anaerobic Threshold and Respiratory Compensation Point Identification During Cardiopulmonary Exercise Tests in Chronic Heart Failure