Anaerobic threshold and respiratory compensation point identification during CPET in chronic heart failure

Background. We evaluated the prognostic significance of the simple presence or absence of identifiable anaerobic threshold (AT) and respiratory compensation point (RCP) at cardiopulmonary exercise test (CPET) performed with a maximal incremental exercise protocol. Methods. In the present multicenter study, we retrospectively analyzed data of 1995 reduced-ejection-fraction heart failure (HFrEF) patients. All underwent clinical and laboratory evaluation, echocardiography, and maximal CPET at baseline. The analysis was performed according to absence of identified AT and RCP (group 1, n=292, 15%), presence of AT but absence of identified RCP (group 2, n=920, 46%), and presence of both AT and RCP (group 3, n=783, 39%). The study endpoint was the composite of cardiovascular mortality/urgent heart transplantation/left ventricular assist device implantation. Results. Median follow-up was 2.97 years (interquartile range 1.50–5.35 years). Eighty-seven (30%), 169 (18%), and 111 (14%) events were observed in group 1, 2, and 3, respectively (p= 0.025). Compared to group 3 (best survival patients), the likelihood of reaching the study endpoint increased 2.7 times when neither AT nor RCP were identified (HR 2.74), and 1.4 times when only AT was identified (HR=1.39). Moreover, adding the presence/absence of identified AT and RCP improved peak VO2 prognostic power, since a significant reclassification was obtained (3.57%, 95% CI 1.9%, 5.2%, p <0.001). Conclusion. AT and RCP identification has a potential role in the prognostic stratification of HFrEF.背景：本研究旨在评估采用极量递增运动方案进行心肺运动试验（cardiopulmonary exercise test, CPET）时，仅以可识别的无氧阈值（anaerobic threshold, AT）与呼吸代偿点（respiratory compensation point, RCP）的存在与否这一简单指标对预后的预测价值。 方法：本项多中心研究回顾性分析了1995例射血分数降低型心力衰竭（reduced-ejection-fraction heart failure, HFrEF）患者的临床资料。所有患者均接受基线临床与实验室评估、超声心动图检查及极量CPET。本研究根据AT与RCP的检出情况将患者分为三组：未检出AT与RCP者（组1，n=292，占比15%）、检出AT但未检出RCP者（组2，n=920，占比46%），以及同时检出AT与RCP者（组3，n=783，占比39%）。本研究的复合终点为心血管死亡、紧急心脏移植或左心室辅助装置植入。 结果：中位随访时间为2.97年（四分位间距1.50~5.35年）。组1、组2、组3分别观察到87例（30%）、169例（18%）及111例（14%）不良事件（P=0.025）。与预后最优的组3相比，未检出AT与RCP的患者达到研究终点的风险升高2.7倍（风险比（hazard ratio, HR）=2.74），仅检出AT的患者风险升高1.4倍（HR=1.39）。此外，纳入AT与RCP的检出情况可提升峰值摄氧量的预后预测效能，且可实现显著的重新分类（3.57%，95%置信区间1.9%~5.2%，P<0.001）。 结论：AT与RCP的检出情况可用于HFrEF患者的预后分层，具有潜在临床应用价值。