Blood Lactate AUC Is a Sensitive Test for Evaluating the Effect of Exercise Training on Functional Work Capacity in Patients with Chronic Heart Failure.

Jae-Young Lim,Torstein Valborgland,Alf Inge Larsen,Peter Scott Munk,Kjetil Isaksen

doi:10.1155/2021/6619747

Abstract

Purpose Exercise training is an essential treatment option for patients with chronic heart failure (CHF). However, it remains controversial, which surrogate measures of functional work capacity are most reliable. The purpose of this paper was to compare functional capacity work measured as capillary lactate concentrations area under the curve (AUC) with standard cardiopulmonary exercise testing (CPET) with VO2peak and the 6-minute walk test (6 MWT). Methods Twenty-three patients in New York Heart Association (NYHA) class II/III with left ventricular ejection fraction (LVEF) <35% were randomised to home-based recommendation of regular exercise (RRE) (controls), moderate continuous training (MCT) or aerobic interval training (AIT). The MCT and AIT groups underwent 12 weeks of supervised exercise training. Exercise testing was performed as standard CPET treadmill test with analysis of VO2peak, the 6 MWT and a novel 30-minute submaximal treadmill test with capillary lactate AUC. Results All patients had statistically significant improvements in VO2peak, 6 MWT and lactate AUC after 12 weeks of exercise training: 6 MWT (p =0.035), VO2peak (p =0.049) and lactate AUC (p =0.002). Lactate AUC (p =0.046) and 6MWT (p =0.035), but not VO2peak revealed difference between the exercise modalities regarding functional work capacity. Conclusion 6-MWT and lactate AUC, but not VO2peak, were able to reveal a statistically significant improvement in functional capacity between different exercise modalities.

Highlights

Maximal oxygen consumption (VO2peak) obtained during a cardiopulmonary exercise test (CPET) is considered an important prognostic indicator for morbidity and mortality [1, 2] in patients with chronic heart failure (CHF), and it is regarded the gold standard for assessing functional work capacity (FWC)
Exercise testing was performed as standard CPET treadmill test with analysis of VO2peak, the 6-minute walk test (6 MWT) and a novel 30-minute submaximal treadmill test with capillary lactate area under the curve (AUC)
For baseline characteristics see Table 1. This was a sub-study of the SmartEx trial (Clinical trials.gov NCT00917046) conducted to test if aerobic interval training (AIT) would be superior to moderate continuous training (MCT) in reversing cardiac remodelling measured as a reduction in left ventricular end diastolic diameter (LVEDD) and improving VO2peak

Summary

Introduction

Maximal oxygen consumption (VO2peak) obtained during a cardiopulmonary exercise test (CPET) is considered an important prognostic indicator for morbidity and mortality [1, 2] in patients with chronic heart failure (CHF), and it is regarded the gold standard for assessing functional work capacity (FWC). This test has been demonstrated to be more sensitive to detect clinical meaningful changes in functional capacity after exercise interventions in the CHF population [4] compared to VO2peak, [5]. In line with this, calculated lactate area under the curve (AUC), using serial capillary blood lactate samples, is a sensitive marker for changes in FWC after exercise intervention in CHF patients [7].

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