Münzer T, Heim C, Riesen W
Institut für Anästhesiologie, Kantonsspital St. Gallen.
Anaesthesist. 1996 Mar;45(3):225-30. doi: 10.1007/s001010050256.
Diagnosis of a perioperative myocardial infarction (PMI) on the basis of measurement of the creatine kinase MB fraction (CKMB) alone is not always easy. Surgical traumatisation of muscle fibres can lead to false-positive elevations. Newly introduced laboratory tests for cardiac troponins seem to facilitate the diagnosis of PMI. We measured serum values of cardiac troponin T in 139 patients described in detail in part I and compared them with common diagnostic tools for myocardial infarction.
In all, 139 patients were enrolled (part I). Clotted serum samples were taken preoperatively and daily until day 3, centrifuged, and stored at -20 degrees C until analysis. Our Department of Clinical Biochemistry and Haematology used a commercially available sandwich immunoassay (Troponin T ELISA, Boehringer, Mannheim, Germany). The measurements of CK and CKMB were performed with an automated analyser (CK, CK-MB, Boehringer, Mannheim, Germany). Serum values of troponin T were defined according to company recommendations: detection level: 0.04 ng/ml, threshold value for myocardial ischaemia: > or = 0.2 ng/ml, value for diagnosis of non-Q-wave infarction: > or = 1.0 ng/ml, and value for diagnosis of Q-wave infarction: > or = 3.0 ng/ml. We therefore assumed a value of > or = 1.0 ng/ml troponin T as being positive for MI, comparable with a CKMB value > or = 6% of total CK (part I). Statistical analysis was the same as described in part I.
Six of the 139 patients had a perioperative infarction, 3 of them had CKMB levels > or = 6%, 3 had an elevation of troponin T > or = 1.0 ng/ml. The sensitivity was 50% for both troponin T and CKMB. Values for specificity were 98% for troponin T and 95% for CKMB. Two of 8 patients with troponin T levels > or = 0.2 ng/ml preoperatively had a reinfarction (Table 5). Three of 8 patients with preoperative elevations of cardiac troponin T > or = 0.2 ng/ml versus 4 of 131 others had left ventricular failure postoperatively (P < 0.05). On day 3 significantly more patients with pathological levels of troponin T had left ventricular failure (5 of 12 vs. 0 of 127, P < 0.05). Patients with pathological depression of the ST segment on Holter ECG more often had elevations of troponin T values on day 3 than patients without (3 of 25 vs. 4 of 75, P = 0.048). There was an unexplained coincidence of elevated preoperative serum creatinine levels > 120 mumol/l and troponin T values (Table 6).
Troponin T is a highly specific marker for perioperative myocardial cell necrosis. Patients with raised levels preoperatively seem to be at higher risk for postoperative reinfarction and left ventricular failure. The prognostic value of such an elevation is not clearly defined, especially in patients with chronic renal failure.
仅基于肌酸激酶同工酶（CKMB）测量来诊断围手术期心肌梗死（PMI）并不总是容易的。肌肉纤维的手术创伤可导致假阳性升高。新引入的心肌肌钙蛋白实验室检测似乎有助于PMI的诊断。我们测量了在第一部分中详细描述的139例患者的血清心肌肌钙蛋白T值，并将其与心肌梗死的常用诊断工具进行了比较。
总共纳入139例患者（第一部分）。术前及术后每日采集血清样本，直至第3天，离心后于-20℃保存直至分析。我们临床生物化学与血液学系使用了一种市售的夹心免疫测定法（肌钙蛋白T酶联免疫吸附测定，德国曼海姆宝灵曼公司）。CK和CKMB的测量使用自动分析仪（CK、CK-MB，德国曼海姆宝灵曼公司）。肌钙蛋白T的血清值根据公司建议定义：检测水平：0.04 ng/ml，心肌缺血阈值：≥0.2 ng/ml，非Q波梗死诊断值：≥1.0 ng/ml，Q波梗死诊断值：≥3.0 ng/ml。因此，我们将肌钙蛋白T值≥1.0 ng/ml视为MI阳性，这与CKMB值≥总CK的6%相当（第一部分）。统计分析与第一部分所述相同。
139例患者中有6例发生围手术期梗死，其中3例CKMB水平≥6%，3例肌钙蛋白T升高≥1.0 ng/ml。肌钙蛋白T和CKMB的敏感性均为50%。肌钙蛋白T的特异性值为98%，CKMB的特异性值为95%。术前肌钙蛋白T水平≥0.2 ng/ml的8例患者中有2例再次梗死（表5）。术前心肌肌钙蛋白T升高≥0.2 ng/ml的8例患者中有3例术后发生左心室衰竭，而其他131例患者中有4例发生左心室衰竭（P<0.05）。在第3天，肌钙蛋白T水平异常的患者发生左心室衰竭的比例明显更高（12例中的5例对127例中的0例，P<0.05）。动态心电图ST段病理性压低的患者在第3天肌钙蛋白T值升高的情况比无此情况的患者更常见（25例中的3例对75例中的4例，P = 0.048）。术前血清肌酐水平>120 μmol/l与肌钙蛋白T值升高存在无法解释的巧合（表6）。
肌钙蛋白T是围手术期心肌细胞坏死的高度特异性标志物。术前水平升高的患者术后再次梗死和左心室衰竭的风险似乎更高。这种升高的预后价值尚未明确界定，尤其是在慢性肾功能衰竭患者中。
