Canver C C, Heisey D M, Nichols R D, Cooler S D, Kroncke G M
Section of Cardiothoracic Surgery, William S. Middleton Memorial Veterans Hospital, University of Wisconsin School of Medicine, Madison 53792-3236, USA.
J Cardiovasc Surg (Torino). 1998 Feb;39(1):57-63.
Although the internal thoracic artery (ITA) graft is well known for its benefit of enhancing patient longevity after coronary artery bypass grafting (CABG), whether its superior patency is associated with improved patient survival at all levels of left ventricular function is unknown. The purpose of this study was to determine whether the use of ITA grafting during CABG confers improved survival benefit to patients with impaired preoperative left ventricular function.
A retrospective chart review was performed in 966 patients who had undergone isolated primary CABG between 1984 and 1995. The study population included 320 patients with only venous conduits (no-ITA group) and 646 patients with at least one ITA conduit (ITA group). A Cox partial likelihood approach was used to model the instantaneous mortality risk ratios as functions of ITA use and preoperative ejection fraction (EF). The forward stepwise regression model specifically examined the following potential confounders in the risk analyses: year of operation, patient age, weight, body surface area, graft location, number of grafts, perfusion time, ischemia time and Veterans Administration preoperative cardiac surgical risk estimates.
Early (30-day) mortality in the ITA group (0.5%) was lower than the no-ITA group (4.1%) (p=0.0004). While 91% of the ITA group patients were still alive, only 70% of the no-ITA group patients were long-term survivors (p=0.0001). The ITA risk ratios for the increasing proportions of EF were not the same. In patients with E<0.40, the ITA risk ratio, 2.96, was significantly different (p=0.0001). It was only for EF >0.46, a significant survival benefit due to an ITA graft could be detected. The ITA-EF relationship was not confounded by the inclusion of those potential confounding variables in the model.
Patient survival after CABG using an ITA graft may be affected by the level of preoperative EF. The internal thoracic artery-specific patient survival benefit appears to be less in a patient with poor left ventricular function.
尽管胸廓内动脉（ITA）移植物因能提高冠状动脉旁路移植术（CABG）后患者的长期生存率而闻名，但在左心室功能的各个水平上，其较高的通畅率是否与患者生存率提高相关尚不清楚。本研究的目的是确定在CABG期间使用ITA移植物是否能为术前左心室功能受损的患者带来更高的生存获益。
对1984年至1995年间接受单纯初次CABG的966例患者进行回顾性病历审查。研究人群包括320例仅使用静脉移植物的患者（非ITA组）和646例至少使用一根ITA移植物的患者（ITA组）。采用Cox部分似然法将瞬时死亡风险比建模为ITA使用情况和术前射血分数（EF）的函数。向前逐步回归模型在风险分析中特别检查了以下潜在混杂因素：手术年份、患者年龄、体重、体表面积、移植物位置、移植物数量、灌注时间、缺血时间和退伍军人管理局术前心脏手术风险评估。
ITA组的早期（30天）死亡率（0.5%）低于非ITA组（4.1%）（p = 0.0004）。ITA组91%的患者仍存活，而非ITA组只有70%的患者是长期幸存者（p = 0.0001）。随着EF比例的增加，ITA风险比并不相同。在EF<0.40的患者中，ITA风险比为2.96，有显著差异（p = 0.0001）。仅在EF>0.46时，才能检测到使用ITA移植物带来的显著生存获益。模型中纳入这些潜在混杂变量并没有混淆ITA-EF关系。
使用ITA移植物进行CABG后的患者生存率可能受术前EF水平的影响。对于左心室功能较差的患者，胸廓内动脉特有的患者生存获益似乎较小。
