| المجلد 3 , العدد 8 , جمادى الآخرة 1426 - تموز (يوليو) 2005 |
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| الواصمات القلبية، علاقة - اعتداد |
| Cardiac Markers
Significance – Correlation
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| د. محمد علي قعدان و د. رولى فرح |
| Kaadan M.A. and Farah R. |
| الملخص Abstract |
إن الواصمات القلبية مشعرات حساسة لإنذار ذبحة غير واضحة وتشخيص (تقييم الوخامة) احتشاء عضل القلب (AMI).
تكون بعض الواصمات (ميوغلوبين – Mb) غير نوعية للحكم على AMI أو عدمه.
تكون الأخرى (متماثلات CK-MB) أكثر نوعية في المراحل المبكرة لكنها أكثر صعوبة لتنجز بشكل روتيني.
يكون زمن ترتيب الاختبارات حاسماً في التدبير العلاجي الملائم للمرضى الذين يتم قبولهم لإصابتهم بالذبحة.
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Cardiac markers are sensitive indicators for prognosis unexplained angina and diagnosis (assessment of severity) of myocardial infarction AMI.
Some markers (Myoglobin–Mb) are nonspecific to rule in/out AMI.
Others (CK-MB isoforms) are more specific in early stages but more difficult to perform routinely.
The time of ordering different tests is crucial in the proper management of patients admitted with angina
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Introduction
Current cardiac markers available and their characteristics:
-Myoglobin (Mb):
Source: Cardiac (+++) and skeletal muscles (++).
Diagnostic Window (D.W.):
It rises within 2-3 h, reach peak concentration at 6-9 h., and return to normal after 24-36 h. Its an early nonspecific test to rule in/ out AMI.
-CK-MB isoforms:
Source: Cardiac (+++) and skeletal muscles (++).
D.W.: It rises within 2-6 h., reach peak conc. At 6-12 h., and return to normal after 24-36 h. Its an early highly specific tool in suspected AMI.
-CK-MB isoenzyme (mass):
Source: Cardiac (+++) and skeletal (+) muscles.
D.W.: It rises within 4-6 h., reach peak conc. At 12-24 h. and return to normal after 48 h. It’s the gold standard marker for early diagnosis of AMI.
-Ischemic modified albumin (IMA):
Source: Ischemic tissues.
D.W.: It rises within minutes of ischemic complaint. Very useful in E.R. for ruling in/out prognosis in unexplained angina.
-?-type natriuretic peptide:
Useful in ruling in/out congestive heart failure in E.R. and in the diagnosis of chronic obstructive pulmonary disease (COPD).
-Troponin I (cTn I):
Source: Cardiac muscles.
D.W.: It rises within 4-8 h., reach peak conc. at 14-18h., and return to normal after 5-9 days.
Its highly specific in myocardial injury, in delayed medical attention, and in stratifying angina patients.
-Troponin T (cTn T):
Source: Cardiac muscles.
D.W.: It rises within 4-8 h., reach peak conc. at 14-18 h. and return to normal after 14 days. It has the same diagnostic characteristics as Troponin I.
Materials and Methods:
CK , CK-MB Kits (Diasys , Bayer)
AXON Bayer, MC 15 Diasys Analyzers.
Roche Troponin T Quantitative tests.
Troponin T Card reader (Roche Diagnostics).
Procedure:
130 patients admitted to E.R. unit in Albassel cardiac center for suspected AMI . CK , CK-MB and Troponin T were tested for evaluation.
91 out of the 130 (70 %) tested Negative for Troponin T, but results of CK-MB were distributed as follow:
< 10 U/L 6 patient
10-20 U/L 38 "
> 20 U/L 47 "
39 patients (30 %) were tested positive for Troponin T, but results of CK-MB were distributed as follow:
< 10 U/L 1 patient
10-20 U/L 13 "
> 20 U/L 25 "
Considering a cut off value of 20 U/L for CK-MB, there was a poor correlation between Troponin T and CK-MB results (52% of Negative Troponin T were significantly positive for CK-MB).
The ratio of CK-MB/CK total was considered as a possible marker for correlation with Troponin T.:
Considering a value of > 6 % as significant in AMI, there was a very poor correlation . 85 out of 90 Troponin T negative patients had > 6 % ratio results.
Conclusions:
The time of ordering different tests could be the reason for the discrepancy between the results obtained in this study.
The prognosis and the diagnosis of AMI cases depends crucially on the so called diagnostic window D.W. which is the time frame of initial rise, peak and return to normal values as listed above.
It is also equally important to evaluate the results sequentially when establishing or ruling out AMI.
The values of CK-MB alone should not be considered for evaluating the prognosis of AMI. Rather, its more valuable to consider the CK-MB/CK total ratio as a better marker along with other cardiac markers.
References
1-Sounders Manual of clinical Laboratory Science, 1998.
2-Henry 20th Edition, 2001.
3-Teitze Textbook of Clinical Chemistry 3d Edition, 1999.
4-Randox Publications, 2003.
Roche Diagnostics Publications, 2001.
5-Bayer`s Manual of Axon Biochemistry Analyzer.
6-Diasys Publications 2002.
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| المجلد 3 , العدد 8 , جمادى الآخرة 1426 - تموز (يوليو) 2005 |
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