缺血修饰白蛋白测定对急性心肌缺血早期诊断的应用与评价

Utility of ischemia-modified albumin in the early diagnosis of acute myocardial ischemia

目的探讨缺血修饰白蛋白(IMA)测定在急性心肌缺血早期诊断中的应用价值。方法①建立并应用白蛋白-钴结合(ACB)试验对729例健康体检者(健康对照组)和182例急性心肌缺血患者(急性心肌缺血组)血清IMA水平进行双盲观察,并对首诊患者同时进行心脏肌钙蛋白I(cTnI)和心电图检测。②以ROC曲线分析IMA测定的临界(cutoff)值、敏感度、特异度、阴性预测值和正确诊断指数。③观察68例经皮冠状动脉内介入治疗(PCI)术前与术后即刘患者IMA水平的变化以及63例急性冠脉综合征(ACS)患者于入院首次、1d、3d、7d和14d IMA水平的动态改变及cTnI的阳性率,了解短暂缺血后即刻IMA水平的变化以及IMA与病程的关系。④测定30例急性脑缺血患者的IMA水平,与急性心肌缺血组进行比较。结果①急性心肌缺血组IMA水平为(0.561±0.120)吸光值(ABSU),阳性率为89.0%,健康对照组为(0.318±0.081)ABSU和5.6%,差异有统计学意义(P<0.01)。②ACS患者首诊IMA、心电图、cTnI的阳性率分别为80.4%、75.4%和58.7%;将IMA与心电图以及IMA与cTnI联合测定首诊检测ACS阳性率可分别提高至93.9%和87.9%。③PCI术后即刘动脉血浆IMA水平为(0.587±0.119)ABSU,较其术前(0.465±0.093) ABSU明显升高(P<0.05)。首诊ACS患者IMA平均水平为(0.527±0.088)ABSU,并于入院1d达峰值,随后逐渐下降,至入院14d有52.4%患者IMA转为阴性。④IMA在ROC曲线下面积为0.971,当cutoff值为0.45 ABSU时,其敏感度、特异度、阴性预测值和正确诊断指数综合评价为最佳,分别是0.890、0.944、0.972和0.834。⑤急性脑缺血患者与健康对照组间IMA水平差异有统计学意义,与急性心肌缺血组相比,IMA水平差异无统计学意义。结论IMA对ACS早期诊断具有高阴性预测值、高敏感度和出现时间早等优点,其与心电图和cTnI联合诊断可提高早期发现急性心肌缺血的敏感性,但IMA在非心源性缺血情况下也可升高,解释其阳性结果时应加以考虑。

Objective To evaluate the role of ischemia-modified albumin （IMA） in the early diagnosis of acute myocardial ischemia. Methods （1）Albumin cobalt-binding（ACB） test was established for the detection of IMA levels. We enrolled 182 patients with acute myocardial ischemia and 729 healthy controls. Cardiac troponinI （cTnI） levels were assayed and ECG were recorded in some patients. （2） The IMA levels were analysed through ROC. The cut-off value, sensitivity and specificity were also got in the ROC, positive results were above the cut-off value , calcuted the area under the ROC and evaluate its negative predictive value and Youden＇ s index. （3） We assessed the IMA levels in 68 patients before percutaneous transluminous coronary angiography （PTCA） and immediately after balloon inflation. 63 ACS patients respecitively were assayed lh , 1d, 3d, 7d and 14d after hospitalization, to evaluate the change of IMA after transient ischemia and the correlations among IMA, cTnI and the duration of disease. （4）Determination of 30 cases of acute cerebral ischemia in patients with IMA,and compared with acute myocardial ischemia group. Results （1）The IMA levels and positive rates in patients with acute myocardial ischemia （0.561 ±0. 102 ABSU, 89.0%） were higher than those of controls （0.318 ±0.081 ABSU, 5.6%） ,P 〈0. 05. （2） In 138 ACS patients , the positive rates of IMA,ECG and cTnI were respectively 80. 4% ,75.4% and 58. 7%. When IMA was combined with ECG, the diagnostic positive rate rised to 93.9%. When IMA was combined with cTnI,the diagnostic positive rate rised to 87.9%. （3）The IMA levels before PTCA in 68 patients were higher than that immediately after balloon inflation , respectively （0. 465 ± 0. 093 ） ABSU and （0. 587 ± 0. 119 ） ABSU, P 〈 0. 05. IMA levele in 63 ACS patients at presentation was （0. 527 ± 0. 088 ） ABSU, it reached the peak 1 d after presentation, then decreased gradually, IMA level in 52. 4% patients turned to negative 14d later. （4）The area under the ROC curve for IMA was 0. 971, at a cutoff of 0. 45 ABSU, the sensitiviy, specificy, negative predictive value, positive predictive value and Youden＇ s index of IMA were 0. 890,0. 944,0. 972 and 0. 834, respectively. （5） The IMA level of acute cerebral ischemia group compared with the heathy control group were positive; Compared with acute myocardial ischemia group, there is no statistically significant. Conclusion IMA is a sensitive biomarker for early detection of acute myocardial ischemia. IMA has a high negative predictive value with high sensitivity. A combination of IMA and ECG or IMA and cTnI will significantly improve the sensitivity in the early diagnosis of myocardial ischemia. IN non-cardial ischemia circumstances, IMA can also increase. So explaining its positive results should be consitered.