Biological Variation Of Cardiac Markers And Its Application Evaluation

[Objective]To study the biological variation within the individual(CVi)and biological variation between individuals(CVG)of six common cardiac markers:cardiac troponin T(cTnT),creatine kinase isoenzyme-MB(CK-MB),myoglobin(MYO),Heart-type fatty acid binding protein(H-FABP),N-terminal pro-B-type natriuretic peptides(NT-pro BNP),and High-sensitivity C-reactive protein.The reference change value(RCV)and individual index(II)of biological variation were studied.The ROC curve was used to evaluate the application of the above cardiac markers in acute myocardial infarction(AMI),which can provide valuable laboratory data for the diagnosis,treatment,prognosis and the formulation of an individualized diagnosis and treatment scheme of patients with clinical cardiovascular disease.[Methods]1.Through a questionnaire survey,53 healthy adult volunteers were recruited.Blood was collected in 4 consecutive weeks at intervals of 1 week for each study subject.All blood samples were taken using VACUETTE@ 4ml red serum Vacuum blood collection tube.Blood was collected on a fixed day and time(between 8:00 and 10:00 in the morning).Blood samples were taken four times at a time for a period of four weeks.Blood samples were collected,serum was separated,and cTnT,CK-MB,MYO,NT-pro BNP were detected by electrochemiluminescence immunoassay,H-FABP and HS-CRP were detected by latex-enhanced immunoturbidimetric assay,which were used in the study of intra-individual biological variation,inter-individual variation,reference variation,and individual index in healthy adult volunteers.At the same time,a total of 200 patients who admitted to the cardiology department of our hospital with main symptoms of "acute chest pain" in 2017 were collected,including 120 males and 80 females,aged 40-68 years(average age:51 years).Clinical application of cardiac markers in the diagnosis of AMI was evaluated.[Results](1)The intra-individual biological variability of cTnT,CK-MB,MYO,H-FABP,NT-pro BNP and HS-CRP for the six common cardiac markers were 10.31%?27.85%?87.31%?26.62%?218.53%?1.16%,respectively.The inter-individual biological variability of cTnT,CK-MB,MYO,H-FABP,NT-pro BNP and HS-CRP were 4.87%?36.14%?20.02%?16.94%?55.76%?107.50%,respectively.;Reference change values were 29.14%?77.28%?242.24%?74.11%?605.83%?170.87%,respectively;and individual indexes were 2.34%?1.26%?4.47%?1.86%?4.05%?1.15%,respectively.;(2)The biological variation of cardiac markers was different in different items.The largest intra-biological variation in healthy adult volunteers was NT-proBNP(218.53%),and the smallest was cTnT(10.31%).The rest of the items were between the two.The highest genetic variation among individuals with common cardiac markers in healthy adult volunteers was HS-CRP(107.45%),and the smallest was cTnT(4.87%),and the rest of the items were between the two.Healthy volunteers showed large differences in the reference changes of cardiac markers.,The largest was NT-pro BNP(605.83%),and the smallest was cTnT(29.14%)(95%CI(Z=1.96).The rest of the items were in between.The largest individual index of 6 cardiac markers for healthy volunteers was MYO(4.47),and the smallest was HS-CRP(1.17),others were between the two;(3)The levels of cTnT,CK-MB,MYO,and H-FABP in the AMI group were 0.16(0.027-0.045)?/L,14.66(8.57-17.63)gg/L,149(68-234)?g/L,6.33�1.99 ng/L,respectively.The levels of cTnT,CK-MB,MYO and H-FABP in non-AMI groups and were 0.007(0.005-0.010)?g/L and 1.65(1.22-3.08)?g/L,34(25-75)?g/L,4.00�1.56 ng/L,respectively..The levels of cTnT,CK-MB,MYO and H-FABP were significantly different(P<0.05).(4)The four cardiac markers cTnT,CK-MB,MYO and H-FABP were used in the diagnosis of AMI.For cTnT,the area under the curve(AUC)was 0.948,the diagnostic sensitivity was 89.3%,the specificity was 92%,the positive likelihood ratio was 11.6,the negative likelihood ratio was 0.12,and the accuracy of cTnT was significantly better than that of CK-MB and MYO,H-FABP.[Conclusions](1)The data of biological variation,reference change value and individualization index of 6 common cardiac markers based on healthy population in Kunming area were obtained,enriches the biological variation database of cardiac markers;(2)In addition to CK-MB,the individual indices of cTnT,MYO,H-FABP are all greater than 1.4,and the reference interval can be used to evaluate the continuity of patient outcomes,while the use of RCV based on biological variation in CK-MB is more appropriate;(3)cTnT can be used to diagnose AMI by analyzing the ROC curve,its diagnostic accuracy,sensitivity and specificity are superior to other cardiac markers.