Bol E, de Vries W R, Mosterd W L, Wielenga R P, Coats A J
Department of Medical Physiology and Sports Medicine, University Medical Centre Utrecht, The Netherlands.
Int J Cardiol. 2000 Feb 15;72(3):255-63. doi: 10.1016/s0167-5273(99)00195-3.
In this study we analysed the all-cause mortality over a period of maximal 6 years in 60 male patients (age: 63.4+/-8.3 years, mean+/-S.D.), suffering from chronic heart failure with resting left ventricular ejection fraction and E/O2 slope as independent factors. We assessed functional NYHA class (II: n=36, III: n=24), radionuclide left ventricular ejection fraction (29.2+/-10.4%) and peak values of heart rate, O2, CO2, E, anaerobic threshold and exercise duration with an incremental work load test on the treadmill. O2 relative to E was based on the individual slopes of the regression of O2 on E during the first 6 min of exercise. These slopes with other exercise-related variables and factors such as etiology, medication, and NYHA class were analysed with a Cox's Regression Method. A survival time analysis (Kaplan-Meier survival curve) was done to establish the influence of E/O2 slope and left ventricular ejection fraction (both split into above and below median values), as well as their interaction, on survival. From all investigated exercise-related variables. E/O2 slope is the most powerful variable regarding prediction of all-cause mortality in our group of chronic heart failure patients. Concerning risk stratification, the subgroup (n=18) with a relatively high left ventricular ejection fraction (>28%) and flat E/O2 slope (<27.6) had most survivors (77.8%) after about 3 years, while the subgroup (n=12) with a relatively high left ventricular ejection fraction (>28%), but a steep E/O2 slope (>27.6) had least survivors (33.3%). This difference in percentage is highly significant (P=0.0025). The fact that E/O2 slope and left ventricular ejection fraction show comparable main and interaction effects between measures of exercise tolerance (e.g., anaerobic threshold, peak O2, exercise duration) on the one hand, and all-cause mortality on the other, suggests the existence of common sources of variance. Based on our analysis, it is unlikely that effects on all-cause mortality are mediated through phenomena related to exercise tolerance. Therefore, we hypothesize that the effects on exercise tolerance and all-cause mortality both depend on common factors, which cause both cardiac and peripheral organ (c.q. muscular) dysfunctions. Moreover, this study clearly shows that E/O2 slope during incremental exercise is an important prognostic marker for risk stratification in chronic heart failure patients, NYHA class II and III.
在本研究中，我们分析了60例男性慢性心力衰竭患者（年龄：63.4±8.3岁，均值±标准差）最长6年期间的全因死亡率，将静息左心室射血分数和E/O₂斜率作为独立因素。我们评估了纽约心脏病协会（NYHA）心功能分级（II级：n = 36，III级：n = 24）、放射性核素左心室射血分数（29.2±10.4%）以及通过跑步机递增负荷试验测得的心率、氧气、二氧化碳、E、无氧阈值和运动持续时间的峰值。运动期间前6分钟，O₂相对于E是基于O₂对E的回归个体斜率。这些斜率与其他运动相关变量及因素（如病因、用药和NYHA分级）采用Cox回归方法进行分析。进行生存时间分析（Kaplan-Meier生存曲线）以确定E/O₂斜率和左心室射血分数（均分为中位数以上和以下值）及其相互作用对生存的影响。在所有研究的运动相关变量中，E/O₂斜率是我们这组慢性心力衰竭患者全因死亡率预测中最有力的变量。关于风险分层，左心室射血分数相对较高（>28%）且E/O₂斜率平缓（<27.6）的亚组（n = 18）在约3年后幸存者最多（77.8%），而左心室射血分数相对较高（>28%）但E/O₂斜率陡峭（>27.6）的亚组（n = 12）幸存者最少（33.3%）。这一百分比差异具有高度显著性（P = 0.0025）。一方面，E/O₂斜率和左心室射血分数在运动耐力指标（如无氧阈值、峰值O₂、运动持续时间）与另一方面的全因死亡率之间显示出相当的主要和相互作用效应，这表明存在共同的方差来源。基于我们的分析，对全因死亡率的影响不太可能通过与运动耐力相关的现象介导。因此，我们假设对运动耐力和全因死亡率的影响都取决于共同因素，这些因素导致心脏和外周器官（即肌肉）功能障碍。此外，本研究清楚地表明，递增运动期间的E/O₂斜率是NYHA II级和III级慢性心力衰竭患者风险分层的重要预后标志物。
