Queirós Maria Conceição, Mendes Duarte Espregueira, Ribeiro Miguel Almeida, Mendes Miguel, Rebocho Maria José, Seabra-Gomes Ricardo
Serviço de Cardiologia-Hospital de Santa Cruz, Carnaxide.
Rev Port Cardiol. 2002 Apr;21(4):383-98.
The prognostic value of peak oxygen uptake (peak VO2) in patients with left ventricular systolic dysfunction is currently recognized and accepted. Some studies have shown that other cardiopulmonary exercise test (CPET) parameters have additional value.
To evaluate whether our population of patients with left ventricular dysfunction had similar results to those found by other investigators who showed that a slow normalization of oxygen uptake (VO2) during the recovery period of a CPET has prognostic value, and whether the recovery phase parameters have additional prognostic value to peak VO2 in these patients.
We studied 292 consecutive adult patients (81.5% male; mean age 52.4 +/- 10.6 years) with an ejection fraction below 40% (mean 23.6 +/- 8.8%) given their first symptom-limited CPET between 03/1993 and 08/2000. The etiology was ischemic heart disease in 154, idiopathic cardiomyopathy in 130 and other in 8 patients. NYHA class was I in 7%, II in 50.6% and III in 42.4% of the patients. Two years was defined as the maximum follow-up time; it was 551.5 +/- 242.2 days on average, and 62 events (death or cardiac transplantation) occurred. The following parameters were analyzed: peak VO2 (l/min and ml/kg/min), percent predicted peak VO2 (pred VO2) (l/min and ml/kg/min), VO2 every 15 seconds (sec) of the first 3 minutes of recovery (the difference between peak VO2/kg and VO2/kg every 15 sec in the recovery period (dif VO2), expressed in ml/kg/min, and also the time (sec) to reach 50% of peak VO2 (T1/2). It was considered that a combined end-point was reached if patients died or underwent cardiac transplantation.
ROC curves of these parameters showed the following as cut-off values (area under the curve > 0.7) for the occurrence of events: peak VO2 < 60% of pred VO2, dif VO2 at 60 sec (< 3 ml/kg/min), 90 sec (< 5), 120 sec (< 8), 150 sec (< 8.6) and 180 sec (< 10.5) of the recovery and T1/2 > 115 sec. Survival analysis was performed considering pred VO2 < 60%, dif VO2 at 150 sec (the largest area under the curve) and T1/2 > 115 sec. In the survival analysis, when the decrease in VO2 at 150 sec was less than 8.6 ml/kg/min the number of patients with events increased from 9.2% to 43.5% (p < 0.001; log-rank), and when T1/2 was less than 115 sec the number of events increased from 12.3 to 34.2% (p < 0.001; log-rank). When the criteria of T1/2 and dif VO2 at 150 sec were considered together with pred VO2 < 60%, mortality increased from 31 to 54% and from 33 to 51%, respectively (p < 0.001, for both parameters; chi-square).
A slow VO2 kinetics in the recovery period of the CPET by itself identified groups of patients with poor prognosis. The association of these parameters with peak VO2 enhanced the identification of groups at greater risk for events. A global evaluation of the CPET should be performed, considering other parameters besides peak VO2, particularly those related to VO2 kinetics in recovery (T1/2 and dif VO2 at 150 sec) as identified in this study.
目前，左心室收缩功能障碍患者的峰值摄氧量（peak VO₂）的预后价值已得到认可。一些研究表明，其他心肺运动试验（CPET）参数具有额外价值。
评估我们的左心室功能障碍患者群体的结果是否与其他研究者的结果相似，那些研究者表明CPET恢复期氧摄取（VO₂）的缓慢恢复具有预后价值，以及这些恢复阶段参数对这些患者的峰值VO₂是否具有额外的预后价值。
我们研究了1993年3月至2000年8月期间连续纳入的292例成年患者（男性占81.5%；平均年龄52.4±10.6岁），其射血分数低于40%（平均为23.6±8.8%），均接受了首次症状限制性CPET。病因包括缺血性心脏病154例、特发性心肌病130例、其他病因8例。纽约心脏协会（NYHA）心功能分级：I级占7%，II级占50.6%，III级占42.4%。定义两年为最长随访时间；平均随访时间为551.5±242.2天，发生62例事件（死亡或心脏移植）。分析了以下参数：峰值VO₂（升/分钟和毫升/千克/分钟）、预测峰值VO₂百分比（pred VO₂）（升/分钟和毫升/千克/分钟）、恢复前3分钟每15秒的VO₂（恢复期间每15秒峰值VO₂/千克与VO₂/千克的差值（dif VO₂），以毫升/千克/分钟表示），以及达到峰值VO₂的50%所需的时间（秒）（T1/2）。如果患者死亡或接受心脏移植，则认为达到联合终点。
这些参数的ROC曲线显示，事件发生的截断值（曲线下面积>0.7）如下：峰值VO₂<预测VO₂的60%、恢复60秒时的dif VO₂（<3毫升/千克/分钟）、90秒时（<5）、120秒时（<8）、150秒时（<8.6）、180秒时（<10.5）以及T1/2>115秒。考虑预测VO₂<60%、150秒时的dif VO₂（曲线下面积最大）和T1/2>115秒进行生存分析。在生存分析中，当150秒时VO₂的下降小于8.6毫升/千克/分钟时，事件患者数量从9.2%增加到43.5%（p<0.001；对数秩检验），当T1/2小于115秒时，事件数量从12.3%增加到34.2%（p<0.001；对数秩检验）。当将T1/2和150秒时的dif VO₂标准与预测VO₂<60%一起考虑时，死亡率分别从31%增加到54%和从33%增加到51%（两个参数的p均<0.001；卡方检验）。
CPET恢复期VO₂动力学缓慢本身可识别出预后不良的患者群体。这些参数与峰值VO₂的联合可增强对事件高风险群体的识别。应进行CPET的全面评估，除峰值VO₂外，还应考虑其他参数，特别是本研究中确定的与恢复时VO₂动力学相关的参数（T1/2和150秒时的dif VO₂）。
