Guazzi Marco, De Vita Stefano, Cardano Paola, Barlera Simona, Guazzi Maurizio D
Istituto di Cardiologia, Università degli Studi di Milano, Milan, Italy.
Am Heart J. 2003 Sep;146(3):542-8. doi: 10.1016/S0002-8703(03)00321-1.
Peak exercise oxygen uptake (peak VO2) and ventilation to CO2 production (VE/VCO2) slope are established prognostic indicators in patients with chronic heart failure (CHF). A high VE/VCO2 slope, however, does not take into account the level of physical performance as expressed by peak VO2. We hypothesized that the prognostic value of a high VE/VCO2 slope may be improved by normalization for peak VO2 (VE/VCO2/VO2).
One hundred patients with CHF underwent pulmonary function tests at rest (spirometry and lung diffusion capacity) and maximal cardiopulmonary exercise testing. The prognostic value of VE/VCO2 slope, peak VO2 and VE/VCO2/VO2 was probed prospectively.
Twenty-one patients died from cardiac reasons during a mean follow-up of 26 +/- 19 months. Nonsurvivors, compared to survivors, showed a lower peak VO2 (13.6 +/- 4.0 vs 17.5 +/- 4.1 mL x min(-1) x kg(-1), P <.01) and a steeper VE/VCO2 slope (43 +/- 11 vs 31.6 +/- 5.0, P <.01). Nonetheless, in patients whose VE/VCO2 slope exceeded 34 (upper normal limit), there was no correlation with peak VO2 (r = -35, P = not significant). Interestingly 35% of them showed a normal exercise performance (peak VO2 > or =18 mL x min(-1) x kg(-1)). At multivariate analysis, the VE/VCO2 slope showed a prognostic power stronger than that of peak VO2; however, the VE/VCO2/VO2 index retained a prognostic power greater than that of both VE/VCO2 slope and peak VO2. A VE/VCO2/VO2 > or =2.4 signaled cases at higher risk.
Discrepancies between VE/VCO2 slope and peak VO2 may generate uncertainty. Normalization of the former by the latter improves outcome prediction and may be considered a simple and effective way for maximizing the clinical applicability of these 2 indicators.
运动峰值摄氧量（峰值VO₂）和二氧化碳排出量与通气量之比（VE/VCO₂）斜率是慢性心力衰竭（CHF）患者已确立的预后指标。然而，高VE/VCO₂斜率并未考虑到由峰值VO₂所体现的体能水平。我们推测，通过将高VE/VCO₂斜率除以峰值VO₂进行标准化（VE/VCO₂/VO₂），其预后价值可能会得到提高。
100例CHF患者接受了静息肺功能测试（肺量计检查和肺弥散功能）以及最大心肺运动测试。对VE/VCO₂斜率、峰值VO₂和VE/VCO₂/VO₂的预后价值进行了前瞻性研究。
在平均26±19个月的随访期内，21例患者死于心脏相关原因。与存活者相比，非存活者的峰值VO₂较低（13.6±4.0 vs 17.5±4.1 mL·min⁻¹·kg⁻¹，P<.01），且VE/VCO₂斜率更陡（43±11 vs 31.6±5.0，P<.01）。尽管如此，在VE/VCO₂斜率超过34（正常上限）的患者中，其与峰值VO₂并无相关性（r=-0.35，P=无显著性差异）。有趣的是，其中35%的患者运动表现正常（峰值VO₂≥18 mL·min⁻¹·kg⁻¹）。在多变量分析中，VE/VCO₂斜率显示出比峰值VO₂更强的预后能力；然而，VE/VCO₂/VO₂指数的预后能力大于VE/VCO₂斜率和峰值VO₂两者。VE/VCO₂/VO₂≥2.4表明患者处于较高风险。
VE/VCO₂斜率与峰值VO₂之间的差异可能会产生不确定性。用后者对前者进行标准化可改善预后预测，并可被视为一种简单有效的方法，以最大限度地提高这两个指标的临床适用性。
