Christakis G T, Lichtenstein S V, Buth K J, Fremes S E, Weisel R D, Naylor C D
Division of Cardiovascular Surgery, Sunnybrook Health Science Centre, University of Toronto, Ontario, Canada.
Eur J Cardiothorac Surg. 1997 Mar;11(3):515-20. doi: 10.1016/s1010-7940(96)01085-8.
The Warm Heart Investigators Trial randomized isolated coronary bypass patients to cold or warm cardioplegia, and demonstrated that warm cardioplegia significantly reduced the prevalence of low output syndrome and myocardial infarction (as defined by CKMB enzyme release). This study was designed prospectively as a subanalysis of the original trial, to determine the effect of warm heart surgery on high risk patients, who were anticipated to derive the major benefit from warm cardioplegia.
The prespecified endpoint for this study was a composite outcome of morbidity and mortality (death and/or low output syndrome and/or enzymatic myocardial infarction). Only patients with complete data for all outcomes were included, totalling 1374 patients (692 warm cardioplegia, 682 cold cardioplegia) who were randomized in the Warm Heart Investigators Trial. High medium and low risk patients were identified by a multivariate model of predicted risk for the study outcome.
Analysis of the independent and interactive influence of cardioplegia technique and predicted risk demonstrated that warm cardioplegia significantly reduced the overall prevalence of morbidity and mortality (warm: 15.9 versus cold: 25.2%, P < 0.01). However, no significant differences in warm-cold effects were detected among risk terciles. Cardioplegia technique had a similar differential influence on mortality and morbidity in low risk patients (warm: 7.3, cold: 17.4%) as it did in high risk patients (warm: 31.1, cold: 39.9%).
Although our analysis confirms the overall benefits of warm cardioplegia, our unanticipated finding in high risk subjects may be explained by the fact that morbidity and mortality in that patient subgroup is caused not only by poor myocardial protection, but by other clinical and technical factors. Further studies are necessary to identify those patients who might benefit most from improved myocardial protection techniques.
“暖心研究者试验”将单纯冠状动脉搭桥患者随机分为冷停搏液组和温停搏液组，结果表明温停搏液显著降低了低心排综合征和心肌梗死（根据肌酸激酶同工酶释放定义）的发生率。本研究作为原试验的前瞻性亚分析设计，旨在确定心脏温血手术对高危患者的影响，预计这些高危患者将从温停搏液中获得主要益处。
本研究预先设定的终点是发病率和死亡率的综合结果（死亡和/或低心排综合征和/或酶性心肌梗死）。仅纳入所有结局数据完整的患者，共有1374例患者（692例温停搏液组，682例冷停搏液组）参与了“暖心研究者试验”并被随机分组。通过研究结局预测风险的多变量模型确定高、中、低风险患者。
对停搏液技术和预测风险的独立及交互影响分析表明，温停搏液显著降低了发病率和死亡率的总体发生率（温停搏液组：15.9%，冷停搏液组：25.2%，P<0.01）。然而，在风险三分位数之间未检测到温冷效应的显著差异。停搏液技术对低风险患者的死亡率和发病率的差异影响（温停搏液组：7.3%，冷停搏液组：17.4%）与高风险患者类似（温停搏液组：31.1%，冷停搏液组：39.9%）。
虽然我们的分析证实了温停搏液的总体益处，但我们在高危受试者中未预期到的发现可能是由于该患者亚组的发病率和死亡率不仅由心肌保护不佳引起，还由其他临床和技术因素导致。有必要进行进一步研究以确定哪些患者可能从改进的心肌保护技术中获益最大。
