Morales F J, Martínez A, Méndez M, Agarrado A, Ortega F, Fernández-Guerra J, Montemayor T, Burgos J
Department of Cardiology, Virgen del Rocio University Hospital, Cadiz, Spain.
Am Heart J. 1999 Aug;138(2 Pt 1):291-8. doi: 10.1016/s0002-8703(99)70114-6.
Peak oxygen uptake (peak VO(2)) is a reference parameter in the assessment of functional capacity of patients with chronic heart failure, but the procedure for cardiopulmonary exercise testing with expired gas analysis is complex and expensive, so more simple and available methods are desirable.
We compared the usefulness of a time-limited walk test, the 6-minute walk test (6-MT), with that of a symptom-limited walk test, the shuttle walk test (SWT), in the evaluation of patients with moderate to severe chronic heart failure. We prospectively studied 46 clinically stable patients in New York Heart Association class II to IV heart failure with left ventricular ejection fraction <40% (aged 53 +/- 10 years, ejection fraction 23% +/- 8%, New York Heart Association functional class 2.8 +/- 0.7). Each patient performed two 6-MT, two SWT and a cardiopulmonary exercise testing within 2 weeks.
We found a close correlation between distance walked in SWT and peak VO(2 ) (r = 0.83, P <.001) and a moderate correlation between distance in 6-MT and peak VO(2) (r = 0.69, P <.001). Both walk tests showed to be reproducible after just one practice walk. All patients who walked > 450 m in SWT had a peak VO(2) >14 mL/kg/min. The overall discriminatory accuracy for SWT distance was greater than that for 6-MT distance for predicting a peak VO(2 ) <14 mL/kg/min (area under receiver operator characteristic curves 0.97 and 0.83 respectively, P =.02). Stepwise multivariate regression analysis, including clinical, exercise testing, echocardiographic, radionuclide-angiographic, and rest hemodynamic data, showed that distance walked in SWT was the only independent predictor of peak VO(2) (P <.001) and the strongest predictor of percent achieved of age- and sex-predicted peak VO(2) (%PVO(2)) (P <.001), with only age offering additional information (P =.02).
The SWT shows to be a feasible and safe method to evaluate patients with chronic heart failure that strongly and independently predicts peak VO(2) and %PVO(2.) This symptom-limited walk test seems to be more useful than 6-MT in the assessment of functional capacity in these patients.
峰值摄氧量（peak VO₂）是评估慢性心力衰竭患者功能能力的参考参数，但采用呼出气体分析的心肺运动试验程序复杂且费用高昂，因此需要更简单且可行的方法。
我们比较了限时步行试验（6分钟步行试验，6-MT）与症状限制性步行试验（往返步行试验，SWT）在评估中度至重度慢性心力衰竭患者中的有效性。我们前瞻性地研究了46例临床稳定的纽约心脏协会II至IV级心力衰竭患者，其左心室射血分数<40%（年龄53±10岁，射血分数23%±8%，纽约心脏协会功能分级2.8±0.7）。每位患者在2周内进行两次6-MT、两次SWT和一次心肺运动试验。
我们发现SWT中的步行距离与peak VO₂密切相关（r = 0.83，P <.001），6-MT中的步行距离与peak VO₂中度相关（r = 0.69，P <.001）。两种步行试验在仅进行一次预试验步行后均显示具有可重复性。在SWT中步行距离>450 m的所有患者peak VO₂>14 mL/kg/min。在预测peak VO₂<14 mL/kg/min时，SWT距离的总体判别准确性高于6-MT距离（受试者工作特征曲线下面积分别为0.97和0.83，P =.02）。逐步多变量回归分析，包括临床、运动试验、超声心动图、放射性核素血管造影和静息血流动力学数据，显示SWT中的步行距离是peak VO₂的唯一独立预测因素（P <.001），也是年龄和性别预测的peak VO₂达标百分比（%PVO₂）的最强预测因素（P <.001），只有年龄提供额外信息（P =.02）。
SWT是评估慢性心力衰竭患者的一种可行且安全的方法，能强有力且独立地预测peak VO₂和%PVO₂。这种症状限制性步行试验在评估这些患者的功能能力方面似乎比6-MT更有用。
