Guazzi Marco, Dickstein Kenneth, Vicenzi Marco, Arena Ross
Cardiopulmonary Unit, University of Milano, Italy.
Circ Heart Fail. 2009 Nov;2(6):549-55. doi: 10.1161/CIRCHEARTFAILURE.109.881326. Epub 2009 Sep 28.
The six-minute walk test (6MWT) and cardiopulmonary exercise testing (CPET) are the 2 testing modalities most broadly used for assessing functional limitation in patients with heart failure (HF). A comprehensive comparison on clinical and prognostic validity of the 2 techniques has not been performed and is the aim of the present investigation.
Two hundred fifty-three patients diagnosed with systolic (n=211) or diastolic (n=42) HF (age: 61.9+/-10.1 years; New York Heart Association Class: 2.2+/-0.78) underwent a 6MWT and a symptom-limited CPET evaluation and were prospectively followed up. During the 4-year tracking period, there were 43 cardiac-related deaths with an annual cardiac mortality rate of 8.7%. The 6MWT distance correlated with CPET-derived variables (ie, peak Vo(2), Vo(2) at anaerobic threshold, and Ve/Vco(2) slope) and was significantly reduced in proportion with lower peak Vo(2) and higher Ve/Vco(2) slope classes and presence of an exercise oscillatory breathing (EOB) pattern (P<0.01). However, no significant differences were observed in distance covered between survivors and nonsurvivors (353.2+/-95.8 m versus 338.5+/-76.4 m; P=NS). At univariate and multivariate Cox proportional analyses, the association of the 6MWT distance with survival was not significant either as a continuous or dicotomized variable (< or =300 m). Conversely, CPET-derived variables emerged as prognostic with the strongest association found for EOB (systolic HF) and Ve/Vco(2) slope (entire population with HF and patients with a 6MWT< or =300 m).
The 6MWT is confirmed to be a simple and reliable first-line test for quantification of exercise intolerance in patients with HF. However, there is no supportive evidence for its use as a prognostic marker in alternative to or in conjunction with CPET-derived variables.
六分钟步行试验（6MWT）和心肺运动试验（CPET）是用于评估心力衰竭（HF）患者功能受限的两种最广泛使用的检测方式。尚未对这两种技术的临床和预后有效性进行全面比较，而这正是本研究的目的。
253例被诊断为收缩性（n = 211）或舒张性（n = 42）HF的患者（年龄：61.9±10.1岁；纽约心脏协会分级：2.2±0.78）接受了6MWT和症状限制性CPET评估，并进行了前瞻性随访。在4年的追踪期内，有43例心脏相关死亡，年心脏死亡率为8.7%。6MWT距离与CPET得出的变量（即峰值摄氧量、无氧阈值时的摄氧量和每分钟通气量/二氧化碳排出量斜率）相关，并且随着较低的峰值摄氧量、较高的每分钟通气量/二氧化碳排出量斜率等级以及运动性振荡呼吸（EOB）模式的出现而显著降低（P<0.01）。然而，幸存者和非幸存者之间的步行距离未观察到显著差异（353.2±95.8米对338.5±76.4米；P =无显著性差异）。在单因素和多因素Cox比例分析中，6MWT距离与生存的关联无论是作为连续变量还是二分变量（≤300米）均无显著性。相反，CPET得出的变量显示出预后意义，其中EOB（收缩性HF）和每分钟通气量/二氧化碳排出量斜率（整个HF患者群体以及6MWT≤300米的患者）的关联最为显著。
6MWT被证实是用于量化HF患者运动不耐受的简单可靠的一线检测方法。然而，没有支持性证据表明其可作为替代CPET得出的变量或与之联合使用的预后标志物。
