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Considerations about the Diagnostic
Value of Antitissue Antibodies in Acute
Myocardial Infarction (AMI)

C. Zeana*, V. Neagu*, I. Belascu**

*Medical Clinic, Emergency Hospital Bucharest, Romania
**Victor Babes Institute, Bucharest, Romania

SUMMARY
Short time after the onset of AMI some products of cardiac origin enter the blood. At this time the biologic diagnosis is represented by the enzymatic tests, troponine and myoglobine. The native or slightly denaturated cardiac proteins that reached the blood induce an (auto) immune reaction that can be identified by various methods.
The authors studied 52 patients (34 M, 18F) with AMI, starting with the first 24 h of ilness. Serum sampling at 5 days interval for 5 weeks were studied in indirect immunofluorescence on slides from rat organs: heart, stomach, liver and kidney.
The presence of antitissue autoantibodies has been observed in 45 cases (86%). The test run positive in the 15-20 day from the onset of AMI.Among the different types of autoantibodies, those antismooth muscle have been noticed almost constantly. The antisarcolemma antibodies have appeared in high concentration at the patients with Dressler syndrome. Occasionaly antinuclear and anticytoplasmic antibodies were found.
Conclusion: the presence of antismooth muscle antibolies has diagnostic value at those patients late admitted in hospital, with normalized enzymatic tests and non-informative electrocardiogram.

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PREAMBULE
   Short term after the onset of Acute Myocardial Infarction (AMI) some macromolecules of cardiac origin with antigenic properties enter the blood. The myoglobin, troponin, as well as many enzymes used in the diagnosis of AMI can be determined in the plasma as an expression of the release of the content of the cardiomiocytes into the blood. During the cardiac cells lyses many of the cardiac proteins are more or less altered, especially by the lisosomal enzymes. As a consequence of these alterations these proteins, glico and lipoproteins become antigenically foreign, inducing an immune reaction based on antibodies. Dressler syndrome is considered to be a clinical expression of an exaggerated immunological reactivity, inducing an immunological autoaggression.

   Immunofluorescence is one of the best methods for the determination of the autoantibodies. Because these autoantibodies are crossreacting, for the imunofluorescence can be utilized organs from different animal species, rat being more convenient.

HYPOTHESIS
   The autoantibody level and spectrum can help the diagnosis of AMI beyond the first 8-14 dais from the onset of the disease, when the enzymatic tests are no more positive.

MATERIAL AND METHODS
   The authors studied 52 patients (34 males, 18 females) aged 43-82 years (median 59) starting from the first day of illness. Patients suffering from other disease were excluded. Serum samples were performed every 5 dais for at least 4 weeks. The patient sera were tested using the method of indirect immunofluorescence on a battery of rat organs : heart, stomach, liver and kidney. The intensity and the pattern of the immunofluorescence according to the sites of the bright spots (nuclear, nucleolar, mitochondrial, smooth muscle fiber, sarcolemmal, diffuse cytoplasmic) were noticed.

RESULTS
   The presence of the antitissue antibodies has been noticed in 45 cases (86%). No influence of the sex or the age of the patients was noticed. At the great majority of the cases the test run positive in the 15-20th day (earliest 10) from the onset of AMI. All the blood samples preleved beyond the time of pozitivation mentained the same pattern and intensity of the immunofluorescence. As for the type of autoantibodies, the antismooth muscle were noticed in all but 4 positive cases. Antisarcolemmal autoantibodies were noticed in all the 5 patients that developed Dressler syndrome. When different type of autoantibodies were noticed in association, the antismooth muscle fluorescence was the most intense.

DISCUSSION
   In the diagnosis of AMI the highest practical value of a laboratory test is related to its precocious positivation. In this respect myoglobin, troponin and CPK are the most appreciated tests. The negativation of these tests supervenes within 4-6 days. Lacticdehidrogenase pozitivity appears only after 24 hours but is of longer duration. The presence of antismooth muscle antibodies has diagnostic value at those patients lately admitted in hospital, after the normalization of the enzymatic tests. The determination of the autoantibodies is of no use in the diagnosis of AMI in patients suffering from autoimmune disease and especially active hepatitis where they are positive.

   The diagnosis of Dressler syndrome is supported by the high intensity of the immunofluorescence and also by the antisarcolemmal type of the antibodies.

   The cost of the method as well as the necessary skill in performing it prohibits to be used routinely.

CONCLUSIONS

1. The presence of autoantibodies determined in direct immunofluorescence is of diagnostic value in patients with chest pain late admitted in the hospital, especially in those with noninformative electrocardiograms.
2. Antisarcolemmal pattern of the autoantibodies and an intense fluorescence are of help in the diagnosis of the post acute myocardial infarction pericarditis (Dressler syndrome)

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
Scientific Committee
President
Dr. Armando Pacher
Technical Committee - CETIFAC
President
fgaro@fac.org.ar
fgaro@satlink.com
rbretal@fac.org.ar
rbretal@netverk.com.ar
apacher@fac.org.ar
apacher@satlink.com

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