Title: The Importance of Serial Time Point Quantitative Assessment of Cardiac Troponin I in the Diagnosis of Acute Myocardial Damage
Abstract: IntroductIon"Cardiac troponin I" (cTnI) is a highly sensitive and specific myocardial injury marker.cTnI is very useful for evaluating ischemic chest pain wherein biochemical data are not confirmative.Electrocardiography (ECG) changes may not be obvious in all cases of acute myocardial infarction (AMI).Hence, the Joint European Cardiology/American College of Cardiology Committee and the National Academy of Clinical Biochemistry proposed cTnI and cTnT as the appropriate markers for a definitive AMI diagnosis. [1,2]he higher cardiac specificity of cTnI confers superiority over cTnT. [3,4]Clinical study results have demonstrated that elevated serum levels of cTnI are detectable within 4-6 h after the onset of chest pain, reach peak concentration in approximately 12 h and remain elevated for 3-10 days following AMI. [5]Since patients may present with the rise in cTnI at varying times following the onset of symptoms, it is necessary to obtain serial measurements for optimal diagnostic accuracy. [6]e researchers also recommend that each institution establishes their own release patterns of cardiac biomarkers. [7]owever, there have been no established data on cTnI values of the Indian population.Further, published data on serial sampling of cTnI for the Indian population are lacking.Besides, there are no published data for the threshold values of cTnI in nonacute coronary syndrome (ACS) cases in India.Although cTnI is now accepted as a standard marker for definitive AMI diagnosis, creatinine phosphokinase (CPK)Objective: The present study was aimed to establish a threshold value for cardiac troponin I (cTnI) for nonacute coronary syndrome (ACS) participants from the local population and also to determine the importance of serial time point estimation of cTnI in acute myocardial infarction (AMI), non-ST-elevated MI (NSTEMI), and unstable angina cases.Methods: The present study included 194 cases, admitted in ICCU with the complaint of anginal pain; 31 were diagnosed with AMI with typical electrocardiography (ECG) changes; whereas, 48 cases were diagnosed with NSTEMI.The latter group of cases was selected for the time point study of cTnI release at 0-4 h, 6-12 h, 72 h, and 144 h of admission.cTnI levels were assessed using the Abbott ARCHITECT i1000SR system.Results: ACS was clinically ruled out in 98 cases, and cTnI level for them was used to decide cTnI threshold for the non-ACS group.cTnI level was checked in 17 cases of unstable angina.The threshold value of cTnI for non-ACS participants was 0.1 ng/ml and can be considered as cut-off value for the regional population.The data suggested that the peak of cTnI levels in most of the AMI cases reached during 6-12 h.The cTnI levels were lower than 0.1 ng/ml, and no significant change in ECG was noticed in 17 cases of unstable angina.Conclusion: The present study suggested that the repeat of cTnI assay after 4-6 h of admission is required if the initial value is <3 ng/ml.