Applied Research Of Ischemia Modified Albumin For The Diagnosis Of Coronary Heart Disease

[Objective]:The aim of this research is to evaluate the value of IMA for early diagnosis of myocardial ischemia by detecting ischemia-modified albumin (IMA) plasma levels in rabbits acute myocardial ischemia; and to evaluate the value of IMA for the early diagnosis of coronary heart disease(CHD) by combining exercise stress testing (EST) and IMA detection.[Method]:1. Experimental study 50 New Zealand white rabbits were randomly divided into 5 group: (1). Ischemia for 5 minutes=10; (2). ischemia for 30 minutes = 10, (3). ischemia for 5 minutes with esmolol =10;(4) ischemia for 30 minutes with esmolol =10 (5) control group=10. Partial ligation of left anterior descending coronary artery, establish the model of myocardial ischemia,detect IMA,CtnI and CK-MB before ischemia and at 15min, 30min, 1h, 2h, 4h, 8h, 12h, 24h after ischemia; After completion of blood collection,use TTC and Evans blue double staining to determine myocardial ischemia area, and then fixed myocardial samples for routine HE staining ,use TUNEL method to determine apoptosis index(AI).2. Clinical research IMA were measured in 60 patients with EST positive. All of them accepted coronary arteriongraphy(CAG) to confirm if they had CHD. IMA before and after exercise ;between those with and without CHD were compared. Meanwhile we detected IMA in 30 healthy people for control .EST positive standand use 1997 AHA/ACC standand. IMA detection used Albumin Cobalt Binding(ACB) test.CAG used stardant Judkins.3. Statistical analysis SPSS16.0 statistical software was used for data analysis. Normal distribution of measurement datas are indicated by mean±standard deviation (χ±s). IMA,cTnI,CK-MB rusults used repeated measurements analysis of variance; the differences between groups compared by one way ANOVA analysis of variance. Spearman correlation was assessed to evaluate the correlations between IMA and ischemia area,AI. Some clinical research between the two groups used Independent-samples T Test;before and after exercise comparison used paired-samples T Test;count data were analyzed byχ2 Test. The bilateral P <0.05 as have statistically significant difference.[Results]:1. Animal experiments1.1 IMA, CTnI, CK-MB determination IMA raised after 15 minutes of ischemia (P< 0.01), peaked at 4 hours after ischemia; there were statistically significant differences between the four ischemia groups and between them and control group (P <0.05); cTnI did not raised ,and there were not statistically significant differences between five groups(P> 0.05). CK-MB raised in the four ischemia groups,but had not statistically significant differences with control group (P>0.05), and different groups showed no significant difference (P>0.05). Meanwhile,we observed significant correlations between IMA and ischemia area(r=0.834,P<0.01),IMA and AI(r=0.911,P<0.01);significant correlation was also observed between ischemia area and AI(r=0.891,P<0.01).1.2 Determination of ischemia area Ischemia areas were larger in the four ischemia groups than control group (P <0.05);there were significant differences between group ischemia for 5 minutes and ischemia for 30 minutes,group ischemia for 5 minutes with esmolol and ischemia for 30 minutes with esmolol ((P <0.01).But group ischemia for 5 minutes and ischemia for 5 minutes with esmolol,group ischemia for 30 minutes and ischemia for 30 minutes with esmolol had not significantly difference(P>0.05).1.3 Determination of AI AI showed higher in the four ischemia groups than control group(P<0.05),there were significantly differences between five groups (p <0.01).2. Clinical Trials2.1 CAG 60 patients received CAG, CAG (+) (the stenosis≥50%, involved more than one vessel, no new onset of vascular occlusion) in 41 cases (68.3%), CAG (-) (that is, any stenosis <50%) in 19 cases (31.7%).2.2 IMA IMA before EST had no difference with normal control group ( P> 0.05). IMA increased significantly in patients after EST and were much higher in patients with CHD (P < 0.01). A 35 mg/mL was used as cut off value. The IMA of 92.7% patients with positive coronary arteringraphy result were found above the cut off value. Combining with the cut off value the EST to diagnosis CHD had a specificity of 89.5%.[Conclusion]:Compare cTnI and CK-MB, IMA can reflect the occurrence of myocardial ischemia and sustained conditions earlier in reversible myocardial ischemia,IMA is a sensitive marker to reflect myocardial ischemia and ischemia degree. IMA levels raised significantly after exercise in patients with CHD , and combine IMA detection should improve the specificity of EST for diagnosis of CHD.