AimsFrailty is an obstacle to performing cardiopulmonary exercise test (CPET) in patients with chronic heart failure (CHF). We evaluated the usefulness of oxygen uptake efficiency slope (OUES) using a 6 min walk test (6MWT) with portable gas analysis compared with CPET‐derived parameters in patients with CHF.Methods and resultsPatients with CHF who underwent both the 6MWT with portable gas analysis and CPET between December 2016 and May 2020 were retrospectively investigated. The 6MWT‐derived and echocardiographic parameters were compared with the OUES and peak oxygen consumption (VO2) from the CPET. Forty patients were analysed; 50% were male with a mean age of 55.45 ± 14.70 years. Twenty‐six patients (65%) had New York Heart Association Functional Classification II or III dyspnoea. Twenty‐five patients (62.5%) had heart failure (HF) with preserved ejection fraction (EF) (left ventricular EF > 50%), and nine patients (22.5%) had HF with reduced EF (EF < 40%). During the 6MWT, the peak VO2 was 14.97 ± 3.80 mL/kg/min, which was only 74% of the peak VO2 in the CPET, 20.18 ± 5.64 mL/kg/min. The OUES in the 6MWT was lower than that in the CPET (1528.87 ± 579.01 in the 6MWT vs. 1638.69 ± 601.31 in the CPET). The 6 min walk distance (6MWD) and OUES in the 6MWT were positively correlated with the OUES in the CPET (6MWD, r = 0.434, P = 0.005; OUES, r = 0.729, P < 0.001). The OUES in the 6MWT showed the strongest correlation with the OUES in the CPET. When we divided patients into two groups according to peak VO2 in the CPET, the correlation between OUES values of the 6MWT and that of the CPET was consistently confirmed (peak VO2 ≥ 20 mL/kg/min group, r = 0.661, P = 0.001; peak VO2 < 20 mL/kg/min group, r = 0.526, P = 0.021). In addition, the 6MWD, OUES, and peak VO2 in the 6MWT were associated with peak VO2 in the CPET (6MWD, r = 0.627, P < 0.001; OUES, r = 0.452, P = 0.003; and peak VO2, r = 0.492, P = 0.001).ConclusionsIn frail patients with CHF who have difficulty performing maximal exercises, the OUES through the 6MWT may be applied instead of the OUES and peak VO2 from the CPET.

中文翻译：

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摄氧效率斜率在 6 分钟步行测试中对慢性心力衰竭的有用性

目标 虚弱是慢性心力衰竭 (CHF) 患者进行心肺运动试验 (CPET) 的一个障碍。我们使用带有便携式气体分析的 6 分钟步行测试 (6MWT) 与 CPET 衍生参数，评估了 CHF 患者摄氧效率斜率 (OUES) 的有用性。方法和结果接受了带有便携式气体分析的 6MWT 的 CHF 患者对2016年12月至2020年5月期间的CPET进行回顾性调查。将 6MWT 衍生参数和超声心动图参数与 OUES 和峰值耗氧量 (VO2）来自 CPET。对四十名患者进行了分析； 50% 为男性，平均年龄为 55.45 ± 14.70 岁。 26 名患者 (65%) 患有纽约心脏协会功能分类 II 或 III 型呼吸困难。 25 名患者 (62.5%) 患有心力衰竭 (HF)，但射血分数 (EF) 保留（左心室 EF > 50%），9 名患者 (22.5%) 患有 HF 且 EF 降低 (EF < 40%)。在 6MWT 期间，峰值 VO2为 14.97 ± 3.80 mL/kg/min，仅为峰值 VO2 的 74%2在 CPET 中，20.18 ± 5.64 毫升/公斤/分钟。 6MWT 中的 OUES 低于 CPET 中的 OUES（6MWT 中为 1528.87 ± 579.01，而 CPET 中为 1638.69 ± 601.31）。 6 分钟步行距离 (6MWD) 和 6MWT 中的 OUES 与 CPET 中的 OUES 呈正相关 (6MWD,r= 0.434,磷= 0.005;欧埃斯，r= 0.729,磷< 0.001）。 6MWT 中的 OUES 显示出与 CPET 中 OUES 的最强相关性。当我们根据峰值摄氧量将患者分为两组时2在 CPET 中，6MWT 的 OUES 值与 CPET 的 OUES 值之间的相关性得到一致证实（峰值 VO2≥20mL/kg/min组，r= 0.661,磷= 0.001；峰值摄氧量2< 20 mL/kg/min 组，r= 0.526,磷= 0.021）。此外，6MWD、OUES 和峰值 VO26MWT 与峰值 VO2 相关2在 CPET（6MWD，r= 0.627,磷< 0.001；欧埃斯，r= 0.452,磷= 0.003;和峰值摄氧量2,r= 0.492,磷= 0.001）。结论对于难以进行最大运动的虚弱 CHF 患者，可以应用通过 6MWT 的 OUES 代替 OUES 和峰值摄氧量2来自 CPET。