Nieuwland W, Berkhuysen M A, van Veldhuisen D J, van Sonderen E, Viersma J W, Lie K I, Rispens P
Department of Cardiology/Thoraxcenter, University Hospital Groningen, University of Groningen, The Netherlands.
Eur Heart J. 1998 Nov;19(11):1688-95. doi: 10.1053/euhj.1998.1149.
Most studies in chronic heart failure have only included patients with marked left ventricular systolic dysfunction (i.e. ejection fraction < or =0.35), and patients with mild left ventricular dysfunction are usually excluded. Further, exercise capacity strongly depends on age, but age-adjustment is usually not applied in these studies. Therefore, this study sought to establish whether (age-adjusted) peak VO2 was impaired in patients with mild left ventricular dysfunction.
Peak VO2 and ventilatory anaerobic threshold were measured in 56 male patients with mild left ventricular dysfunction (ejection fraction 0.35-0.55; study population) and in 17 male patients with a normal left ventricular function (ejection fraction >0.55; control population). All patients had an old (>4 weeks) myocardial infarction. By using age-adjusted peak VO2 values, a 'decreased' exercise capacity was defined as < or = predicted peak VO2 - 1 x SD (0.81 of predicted peak VO2), and a severely decreased exercise capacity as < or = predicted peak VO2 - 2 x SD (0.62 of predicted peak VO2).
Patients in the study population (age 52+/-9 years; ejection fraction 0.46+/-0.06) were mostly asymptomatic (NYHA class I: n=40, 76%), while 16 patients (24%) had mild symptoms, i.e. NYHA class II. All 17 controls (age 57+/-8 years) were asymptomatic. Mean peak VO2 was lower in patients with mild left ventricular dysfunction (23.6+/-5.7 vs 27.1+/-4.6 ml x min(-1) x kg(-1) in controls, P<0.05). In 75% of the study population patients (n=42) age-adjusted peak VO2 was decreased (NYHA I/II: n=29/13) and in 18% of them severely decreased (n=10; NYHA I/II: n=6/4). In contrast, only three patients (18%) in the control population had a decreased and none a severely decreased age-adjusted peak VO2.
In patients with mild left ventricular dysfunction, who have either no or only mild symptoms of chronic heart failure, a substantial proportion has an impaired exercise capacity. By using age-adjustment, impairment of exercise capacity becomes more evident in younger patients. Patients with mild left ventricular dysfunction are probably under-diagnosed, and this finding has clinical and therapeutic implications.
大多数关于慢性心力衰竭的研究仅纳入了左心室收缩功能明显受损（即射血分数≤0.35）的患者，轻度左心室功能障碍的患者通常被排除在外。此外，运动能力很大程度上取决于年龄，但这些研究通常未进行年龄校正。因此，本研究旨在确定轻度左心室功能障碍患者（年龄校正后）的峰值摄氧量是否受损。
对56例轻度左心室功能障碍男性患者（射血分数0.35 - 0.55；研究人群）和17例左心室功能正常男性患者（射血分数>0.55；对照人群）进行峰值摄氧量和通气无氧阈测量。所有患者均有陈旧性（>4周）心肌梗死。通过使用年龄校正后的峰值摄氧量值，将“运动能力下降”定义为≤预测峰值摄氧量 - 1×标准差（预测峰值摄氧量的0.81），将严重运动能力下降定义为≤预测峰值摄氧量 - 2×标准差（预测峰值摄氧量的0.62）。
研究人群中的患者（年龄52±9岁；射血分数0.46±0.06）大多无症状（纽约心脏协会心功能分级I级：n = 40，76%），而16例患者（24%）有轻度症状，即纽约心脏协会心功能分级II级。所有17例对照者（年龄57±8岁）均无症状。轻度左心室功能障碍患者的平均峰值摄氧量较低（分别为23.6±5.7与对照组的27.1±4.6 ml·min⁻¹·kg⁻¹，P<0.05）。在研究人群中，75%的患者（n = 42）年龄校正后的峰值摄氧量下降（纽约心脏协会心功能分级I/II级：n = 29/13），其中18%的患者严重下降（n = 10；纽约心脏协会心功能分级I/II级：n = 6/4）。相比之下，对照人群中只有3例患者（18%）年龄校正后的峰值摄氧量下降，无患者严重下降。
在轻度左心室功能障碍且无或仅有轻度慢性心力衰竭症状的患者中，相当一部分患者存在运动能力受损。通过年龄校正，运动能力受损在年轻患者中更为明显。轻度左心室功能障碍患者可能未得到充分诊断，这一发现具有临床和治疗意义。
