الفهرس 
ACUTE CORONARY SYNDROMEOnly 14 pages are availabe for public view
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Abstract
Coronary artery diseases (CAD), also known as ischemic heart diseases, are diverse, with a spectrum that comprises various forms of angina pectoris, acute myocardial infarction (AMI), and sudden cardiac death. They are the leading cause of death among adults and one of the most common reasons for emergency department visits worldwide.
For initial assessment of a patient with ACS, clinical history is most useful; but risk factors, ECG, imaging techniques and serum biomarkers, all contribute in confirming the diagnosis. Cardiac troponin (cTn) I and T are the current gold standard for the detection of myocardial necrosis.
In this regard, our study aimed to examine the ability of high-sensitivity cardiac troponin T (hs-TnT) for early detection of AMI in comparison with conventional Troponin assay. In addition, to study the clinical utility of kinetic changes of hs-TnT for diagnosis of ACS.
For this purpose, we recruited 60 subjects including: 50 ACS patients (group I), who admitted to Ain Shams Specialized Hospital emergency unit with acute chest pain, having no or non specific ECG changes and negative for troponin I and 10 healthy subjects as a control group (group II). Patients with STEMI, recent PCI and positive troponin I or having any other disease causing rise of troponin were excluded.
For all patients, hs-TnT was assayed on admission in conjunction with other routine cardiac markers (CK-T, CK-MB and troponin I). Accordingly, they were divided into two subgroups; I-A (n=16) and I-B (n=34) using the cut off 14ng/L (≤14ng/L, >14ng/L respectively).
After 6-8 hours, patients of group I-B were reassessed by routine cardiac markers and hs-TnT, in addition to one case of group I-A who was highly suspicious to be MI.
Later, patients were reclassified after confirmatory cardiological diagnosis into group C; including cases of UA (n=17) and group D; representing cases of NSTEMI (n=33).
Results of the current study revealed that median serum levels of hs-TnT showed highly significant difference between patients with ACS and healthy subjects, and also between patients with NSTEMI and those with UA. Moreover, the present study demonstrated a non-significant association between the levels of hs-TnT and the common risk factors of CAD.
Median absolute and relative kinetic changes of the four parameters were calculated and compared. The hs-TnT showed the highest absolute and relative kinetic change values in the 35 patients, who were reassayed for hs-TnT, being 152ng/L and 145% respectively. Moreover, statistical comparison between the 1st and 2nd samples regarding all cardiac markers done revealed a highly significant change between them but hs-TnT had the highest z value.
Receiver operating characteristic curve (ROC) analysis was applied to assess the diagnostic performance of hs-TnT in discriminating patients from control group. The best cutoff was 4.8ng/L. This cutoff had a diagnostic sensitivity, specificity, PPV, NPV and efficiency of 96%, 100%, 100%, 83.3% and 96.7% respectively. The AUC was 0.966.
Another receiver operating characteristic curve (ROC) analysis was applied to assess the diagnostic performance of hs-TnT for discriminating NSTEMI patients from UA patients. The best diagnostic cutoff for hs-TnT was 13.7ng/L. This had a diagnostic sensitivity, specificity, NPV, PPV and efficiency of 97%, 88.2%, 93.8, 94.1% and 94% respectively. The area under curve (AUC) was 0.966.
In conclusion, serum hs-TnT was significantly higher in ACS patients compared to controls and showed that a cut off 4.8ng/L could discriminate between them. Hs-TnT assay could also discriminate cases of AMI from those with UA using the cut off value 13.7ng/L. Our study also demonstrated highly significant absolute and relative kinetic changes in hs-TnT levels in patients with AMI. Therefore, the use of 2 samples with 6-8 hours interval is better than depending on 1sample only on admission. The hs-TnT can be used for early rule in patients with MI as it could detect 97% of cases with MI whose troponin I were negative and could detect 100% of cases of MI after 6-8 hours compared to troponin I which could detect only 21.2% of cases. This can be of great importance in the future introduction and use of the new high sensitive assay as a non invasive reliable diagnostic tool to replace the currently used invasive diagnostic techniques for patients with ACS.
Coronary artery diseases (CAD), also known as ischemic heart diseases, are diverse, with a spectrum that comprises various forms of angina pectoris, acute myocardial infarction (AMI), and sudden cardiac death. They are the leading cause of death among adults and one of the most common reasons for emergency department visits worldwide.
For initial assessment of a patient with ACS, clinical history is most useful; but risk factors, ECG, imaging techniques and serum biomarkers, all contribute in confirming the diagnosis. Cardiac troponin (cTn) I and T are the current gold standard for the detection of myocardial necrosis.
In this regard, our study aimed to examine the ability of high-sensitivity cardiac troponin T (hs-TnT) for early detection of AMI in comparison with conventional Troponin assay. In addition, to study the clinical utility of kinetic changes of hs-TnT for diagnosis of ACS.
For this purpose, we recruited 60 subjects including: 50 ACS patients (group I), who admitted to Ain Shams Specialized Hospital emergency unit with acute chest pain, having no or non specific ECG changes and negative for troponin I and 10 healthy subjects as a control group (group II). Patients with STEMI, recent PCI and positive troponin I or having any other disease causing rise of troponin were excluded.
For all patients, hs-TnT was assayed on admission in conjunction with other routine cardiac markers (CK-T, CK-MB and troponin I). Accordingly, they were divided into two subgroups; I-A (n=16) and I-B (n=34) using the cut off 14ng/L (≤14ng/L, >14ng/L respectively).
After 6-8 hours, patients of group I-B were reassessed by routine cardiac markers and hs-TnT, in addition to one case of group I-A who was highly suspicious to be MI.
Later, patients were reclassified after confirmatory cardiological diagnosis into group C; including cases of UA (n=17) and group D; representing cases of NSTEMI (n=33).
Results of the current study revealed that median serum levels of hs-TnT showed highly significant difference between patients with ACS and healthy subjects, and also between patients with NSTEMI and those with UA. Moreover, the present study demonstrated a non-significant association between the levels of hs-TnT and the common risk factors of CAD.
Median absolute and relative kinetic changes of the four parameters were calculated and compared. The hs-TnT showed the highest absolute and relative kinetic change values in the 35 patients, who were reassayed for hs-TnT, being 152ng/L and 145% respectively. Moreover, statistical comparison between the 1st and 2nd samples regarding all cardiac markers done revealed a highly significant change between them but hs-TnT had the highest z value.
Receiver operating characteristic curve (ROC) analysis was applied to assess the diagnostic performance of hs-TnT in discriminating patients from control group. The best cutoff was 4.8ng/L. This cutoff had a diagnostic sensitivity, specificity, PPV, NPV and efficiency of 96%, 100%, 100%, 83.3% and 96.7% respectively. The AUC was 0.966.
Another receiver operating characteristic curve (ROC) analysis was applied to assess the diagnostic performance of hs-TnT for discriminating NSTEMI patients from UA patients. The best diagnostic cutoff for hs-TnT was 13.7ng/L. This had a diagnostic sensitivity, specificity, NPV, PPV and efficiency of 97%, 88.2%, 93.8, 94.1% and 94% respectively. The area under curve (AUC) was 0.966.
In conclusion, serum hs-TnT was significantly higher in ACS patients compared to controls and showed that a cut off 4.8ng/L could discriminate between them. Hs-TnT assay could also discriminate cases of AMI from those with UA using the cut off value 13.7ng/L. Our study also demonstrated highly significant absolute and relative kinetic changes in hs-TnT levels in patients with AMI. Therefore, the use of 2 samples with 6-8 hours interval is better than depending on 1sample only on admission. The hs-TnT can be used for early rule in patients with MI as it could detect 97% of cases with MI whose troponin I were negative and could detect 100% of cases of MI after 6-8 hours compared to troponin I which could detect only 21.2% of cases. This can be of great importance in the future introduction and use of the new high sensitive assay as a non invasive reliable diagnostic tool to replace the currently used invasive diagnostic techniques for patients with ACS.