Relationship Between Respiratory Compensation Point and Anaerobic Threshold in Patients With Heart Failure With Reduced Ejection Fraction

Abstract

Background: Cardiopulmonary exercise testing (CPX) is used in the prognostic evaluation of patients with heart failure with reduced ejection fraction (HFrEF). In these patients, the ventilation feedback system is dysfunctional, and overactive peripheral chemoreceptors may be responsible for the early appearance of the respiratory compensation point (RCP) after the anaerobic threshold (AT). The mechanism of RCP appearance remains unknown and very few studies have reported the relationship between RCP and heart failure. We hypothesized that the duration between the RCP and AT (RCP-AT time) can predict the severity of cardiac disorders and prognosis in patients with HFrEF. Methods and Results:We enrolled 143 patients with HFrEF who underwent symptom-limited maximal CPX between 2012 and 2016. During a median follow-up of 1.4 years, cardiovascular death occurred in 45 participants (31%). The patients who died had a significantly shorter RCP-AT time and lower hemoglobin (Hb) levels than those who survived (P<0.001 and P=0.01, respectively). Cox regression analyses revealed RCP-AT time and Hb level to be independent predictors of cardiovascular death in patients with HFrEF (P<0.001 and P=0.018, respectively).Conclusions: RCP-AT time can better predict prognosis in patients with HFrEF than the magnitude of increase in oxygen consumption within the isocapnic buffering domain (∆V O2 AT-RCP). It may be useful as a new prognostic indicator in these patients.

The Ratio of Oxygen Uptake From Ventilatory Anaerobic Threshold to Respiratory Compensation Point Is Maintained During Incremental Exercise in Older Adults

“…Symptomatic maximal exercise was performed using a ramp protocol of 5-30 watts (W)/min according to age and condition after 2-3 min rest and warm-up of 0-10 W lasting 2-3 min. Rating of perceived exertion (RPE) at the end of the exercise was assessed using the Borg scale (Beaver et al, 1986a;Takano, 2000;Dekerle et al, 2003;Balady et al, 2010;Lenti et al, 2011;Wasserman et al, 2012;Yen et al, 2015Yen et al, , 2018Nishijima et al, 2017Nishijima et al, , 2019Keir et al, 2018;Korkmaz Eryılmaz et al, 2018;Carriere et al, 2019;Iannetta et al, 2019;Nakade et al, 2019).…”

“…In previous reports, the time in the IB phase ( Tanehata et al, 1999 ; Nakade et al, 2019 ) and ΔVO 2 RCP-VAT ( Lenti et al, 2011 ; Carriere et al, 2019 ) have been used to define the IB phase; however, exercise tolerance indices such as peak VO 2 decline with age. The time can only be compared with the same protocol [it may be possible to adjust it; however, an adjustment is not desirable because of the errors in the load acceleration and oxygen uptake ( Hansen et al, 1987 )].…”