Is the Verification Phase a Suitable Criterion for the Determination of Maximum Oxygen Uptake in Patients with Heart Failure and Reduced Ejection Fraction? A Validation Study.

The verification phase (VP) has been proposed as an alternative to the traditional criteria used for the determination of the maximum oxygen uptake (VO 2 max) in several populations. Nonetheless, its validity in patients with heart failure with reduced ejection fraction (HFrEF) remains unclear. Therefore, the aim of this study was to analyse whether the VP is a safe and suitable method to determine the VO 2 max in patients with HFrEF. Adult male and female patients with HFrEF performed a ramp-incremental phase (IP), followed by a submaximal constant VP (i.e., 95% of the maximal workload during the IP) on a cycle ergometer. A 5-min active recovery period (i.e., 10 W) was performed between the two exercise phases. Group (i.e., median values) and individual comparisons were performed. VO 2 max was confirmed when there was a difference of ≤ 3% in peak oxygen uptake (VO 2 peak) values between the two exercise phases. Twenty-one patients (13 males) were finally included. There were no adverse events during the VP. Group comparisons showed no differences in the absolute and relative VO 2 peak values between both exercise phases ( p = 0.557 and p = 0.400, respectively). The results did not change when only male or female patients were included. In contrast, individual comparisons showed that the VO 2 max was confirmed in 11 patients (52.4%) and not confirmed in 10 (47.6%). The submaximal VP is a safe and suitable method for the determination of the VO 2 max in patients with HFrEF. In addition, an individual approach should be used because group comparisons could mask individual differences.