Miyamoto S, Nagaya N, Satoh T, Kyotani S, Sakamaki F, Fujita M, Nakanishi N, Miyatake K
Division of Cardiology, Department of Medicine, National Cardiovascular Center, Osaka, Japan.
Am J Respir Crit Care Med. 2000 Feb;161(2 Pt 1):487-92. doi: 10.1164/ajrccm.161.2.9906015.
The six-minute walk test is a submaximal exercise test that can be performed even by a patient with heart failure not tolerating maximal exercise testing. To elucidate the clinical significance and prognostic value of the six-minute walk test in patients with primary pulmonary hypertension (PPH), we sought (1) to assess the relation between distance walked during the six-minute walk test and exercise capacity determined by maximal cardiopulmonary exercise testing, and (2) to investigate the prognostic value of the six-minute walk test in comparison with other noninvasive parameters. The six-minute walk test was performed in 43 patients with PPH, together with echocardiography, right heart catheterization, and measurement of plasma epinephrine and norepinephrine. Symptom-limited cardiopulmonary exercise testing was performed in a subsample of patients (n = 27). Distance walked in 6 min was significantly shorter in patients with PPH than in age- and sex-matched healthy subjects (297 +/- 188 versus 655 +/- 91 m, p < 0. 001). The distance significantly decreased in proportion to the severity of New York Heart Association functional class. The distance walked correlated modestly with baseline cardiac output (r = 0.48, p < 0.05) and total pulmonary resistance (r = -0.49, p < 0. 05), but not significantly with mean pulmonary arterial pressure. In contrast, the distance walked correlated strongly with peak V O(2) (r = 0.70, p < 0.001), oxygen pulse (r = 0.57, p < 0.01), and V E-VCO(2) slope (r = -0.66, p < 0.001) determined by cardiopulmonary exercise testing. During a mean follow-up period of 21 +/- 16 mo, 12 patients died of cardiopulmonary causes. Among noninvasive parameters including clinical, echocardiographic, and neurohumoral parameters, only the distance walked in 6 min was independently related to mortality in PPH by multivariate analysis. Patients walking < 332 m had a significantly lower survival rate than those walking farther, assessed by Kaplan-Meier survival curves (log-rank test, p < 0.01). These results suggest that the six-minute walk test, a submaximal exercise test, reflects exercise capacity determined by maximal cardiopulmonary exercise testing in patients with PPH, and it is the distance walked in 6 min that has a strong, independent association with mortality.
六分钟步行试验是一种亚极量运动试验，即使是无法耐受极量运动试验的心力衰竭患者也能进行。为了阐明六分钟步行试验在原发性肺动脉高压（PPH）患者中的临床意义和预后价值，我们旨在：（1）评估六分钟步行试验中行走的距离与通过极量心肺运动试验测定的运动能力之间的关系；（2）与其他非侵入性参数相比，研究六分钟步行试验的预后价值。对43例PPH患者进行了六分钟步行试验，同时进行了超声心动图、右心导管检查以及血浆肾上腺素和去甲肾上腺素的测定。对部分患者（n = 27）进行了症状限制性心肺运动试验。PPH患者6分钟内行走的距离明显短于年龄和性别匹配的健康受试者（297±188米对655±91米，p < 0.001）。该距离与纽约心脏协会功能分级的严重程度成比例显著降低。行走距离与基线心输出量（r = 0.48，p < 0.05）和总肺阻力（r = -0.49，p < 0.05）呈适度相关，但与平均肺动脉压无显著相关性。相比之下，行走距离与心肺运动试验测定的峰值V O₂（r = 0.70，p < 0.001）、氧脉搏（r = 0.57，p < 0.01）和V E-VCO₂斜率（r = -0.66，p < 0.001）密切相关。在平均21±16个月的随访期内，12例患者死于心肺相关原因。在包括临床、超声心动图和神经体液参数在内的非侵入性参数中，多因素分析显示只有6分钟内行走的距离与PPH患者的死亡率独立相关。通过Kaplan-Meier生存曲线评估，行走距离< 332米的患者生存率明显低于行走更远的患者（对数秩检验，p < 0.01）。这些结果表明，六分钟步行试验这种亚极量运动试验反映了PPH患者通过极量心肺运动试验测定的运动能力，且6分钟内行走的距离与死亡率有很强的独立关联。
