Agreement in Averaging Methods for Cardiopulmonary Exercise Data in Patients with Heart Failure

Abstract

1473 Cardiopulmonary exercise (CPX) testing is commonly performed in patients with heart failure (HF). There are several methods available to express CPX data. The optimal averaging method for reporting peak and submaximal data is not clear. PURPOSE: To assess differences in peak VO2, anaerobic threshold (AT) and respiratory exchange ratio (RER) identified using several common averaging methods among patients with HF. METHODS: We analyzed data from 27 consecutive patients with HF (mean ± SD; age = 56 ± 14 yr, 59% male, ejection fraction = 23 ± 10%) referred for CPX testing. Symptom-limited exercise tests were performed using a low-level, 3-min staged, treadmill protocol. Gas exchange was collected continuously using a Medgraphics CPX/D metabolic cart with BreezeEx software. Data was expressed using the following methods: breath-by-breath (BxB), middle 5 of 7 breaths rolling average (MID5), and 15-s and 30-s interval averages. Using the metabolic cart's software, v-slope (VCO2 vs VO2) graphs were printed and tabular data was exported for each method. Peak VO2 and RER were identified as the highest value during the final minute of exercise. AT was identified using the v-slope method. ANOVA was used to analyze the difference between reporting methods. RESULTS: See Table. Peak VO2 identified using BxB was significantly higher (p = 0.03) than the other methods. There was no significant difference between MID5, 15-s and 30-s for peak VO2. There was no significant difference between the reporting methods for AT or RER. CONCLUSIONS: Peak VO2, RER and AT are not different among commonly used averaging methods (e.g., MID5, 15-s, 30-s) in patients with HF. Some form of averaging method other than BxB should be considered when reporting CPX data.Table