Viral antibodies in patients with primary myocardial disease

Myocarditis and idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) accounts for 25% of cases of heart failure in the United States. Understanding the relationship between an inciting event or agent and the development of IDC has progressed only recently. Once IDC has developed, treatment is palliative and little can be done to alter the natural course of the disease. Active myocarditis, a suspected precursor of IDC, is myocardial inflammation and injury without ischemia. The disease ranges from a self-limited flulike illness to one of serious consequence with arrhythmias, heart failure, or death. Many agents have been associated with myocarditis, and the clinical manifestations depend on an interplay between the inciting agent and the host response. The development of a murine model and the expanded use of endomyocardial biopsy using the Dallas criteria have increased our understanding of myocarditis and its sequelae. Therapy consists of managing symptoms using conventional medical regimens for heart failure. Immunosuppressive therapy should be reserved for patients with biopsy-proven disease who have failed conventional therapy. Continued deterioration warrants ventricular assistance and consideration of cardiac transplantation.

Similar prevalence of enteroviral genome within the myocardium from patients with idiopathic dilated cardiomyopathy and controls by the polymerase chain reaction

OBJECTIVE

To assess the prevalence and significance of enteroviral genome within myocardial biopsy specimens taken from patients with idiopathic dilated cardiomyopathy and from controls.

DESIGN

Prospective evaluation of myocardial tissue for the presence of an enteroviral genome by the polymerase chain reaction.

SETTING

A tertiary referral centre for patients with idiopathic dilated cardiomyopathy.

PATIENTS

Tissue for the study came from 50 consecutive patients with dilated cardiomyopathy, 41 with other forms of heart disease and 34 from coroners' necropsy cases.

RESULTS

Enteroviral genome was detected in 6/50 (12%) patients with dilated cardiomyopathy and 13/75 (17%) of the controls (not significant). No differences were seen between dilated cardiomyopathy patients with or without myocardial enteroviral genome in respect of age; duration of symptoms; proportion of patients with a premorbid acute viral illness, excess alcohol consumption, or hypertension; New York Heart Association functional class; measures of left ventricular function; or endomyocardial histology. Within the control group enteroviral genome was detected in 3/15 (20%) patients with ischaemic heart disease, 2/19 (10.5%) with valvar heart disease, 1/5 (20%) with specific heart muscle disease, 0/2 (0%) with congenital heart disease, and 7/34 (20.6%) cases of sudden death. During 2-52 month follow up (mean 22) 15/44 (34%) patients without myocardial enteroviral genome and 2/6 (33%) with myocardial enteroviral genome died suddenly or required orthotopic heart transplantation for progressive heart failure.

CONCLUSIONS

These findings do not support the hypothesis that persistent enteroviral infection is of pathogenic or prognostic importance in dilated cardiomyopathy but they are consistent with enterovirus being a common environmental pathogen.

Immunologic regulator and effector functions in perimyocarditis, postmyocarditic heart muscle disease and dilated cardiomyopathy

In acute perimyocarditis we found that OKIAI-positive cells were increased, and in dilated cardiomyopathy OKMI-positive cells were increased. No significant alteration in suppressor T cell activity was observed in our patients with either disease. The characteristic immunofluorescent pattern in carditis and postmyocarditic heart disease is the presence of antimyolemmal antibodies with intact rat and human cardiocytes in titers of 1:40-1:320 as antigens. The antimyolemmal fluorescence can be absorbed with the respective causative virus in Coxsackie B, influenza, mumps and EBV-myocarditis, indicating that the antibodies are a cross-reactive. AMLA-positive sera induce cytolysis of vital rat cardiocytes in vitro, suggesting that the antibodies are of pathogenetic relevance. Cytolytic serum activity could be absorbed out with the respective virus. Immunohistologic specimens obtained from patients with carditis demonstrate the fixation of IgG and IgM antibodies; IgG antibodies also occur in dilated cardiomyopathy and coronary artery disease. In dilated postmyocarditic heart disease both antimyolemmal fluorescence and cytolytic activity are preserved at a lower level when compared to carditis. These antibodies can also fix complement. In the acute phase of carditis circulating immune complexes can be demonstrated. Cellular effector mechanisms against vital cardiocytes were maintained or even slightly enhanced in carditis, postmyocarditic and primary dilated cardiomyopathy. In vitro NK cell activity against K 562, however, was decreased. This is compatible with a sustained target-specific cytotoxicity whereas reduced NK cell activity may indicate impairment of this effector organ.

A clinicopathologic study on a cause of idiopathic cardiomyopathy and arrhythmia and conduction disturbance employing endomyocardial biopsy

A comparative study of right ventricular histopathologic findings and clinical profiles in 174 cases with hypertrophic cardiomyopathy (HCM), 145 cases with dilated cardiomyopathy (DCM), and 241 cases with idiopathic arrhythmia and/or conduction disturbance with significant myocardial pathology [Electric disturbance type of cardiomyopathy (ECM)], totaling 560 cases, was made in order to clarify the role of viral myocarditis in these conditions. Postmyocarditis change (PMC) was defined by assessing serial biopsy findings in nine cases with acute myocarditis. The PMC was observed in three cases with HCM (1.7%), 22 with DCM (15%), and 21 with ECM (8.7%). The incidence of PMC was significantly higher in DCM and ECM than in HCM (P less than 0.001). The typical pattern of onset of acute myocarditis, i.e., high fever, upper respiratory infection, and gastrointestinal symptoms preceding cardiac symptoms within 10 days, was recognized in one case with HCM, eight with DCM, and 6 of 123 cases with ECM. The incidence was higher in DCM and ECM than in HCM (P less than 0.05). Of 46 cases with PMC, 12 (26%) showed this pattern, on the other hand only 3 of 377 cases (0.8%) without PMC did so (P less than 0.0001). Familial occurrence was not found in any of the 46 cases with PMC but was found in 38 of the 377 cases without PMC (P less than 0.01). This study indicates that viral myocarditis may often be the causative agent of idiopathic cardiomyopathy, especially DCM and ECM. It is also noticed that familial occurrence of the cases with PMC was never seen.

The cardiomyopathies: a review of terminology, pathology and pathogenesis

A classification of the cardiomyopathies based on functional and morphological features is outlined, a detailed account of the pathology of each type is presented and possible pathogenetic mechanisms are reviewed. Myocarditis and its relationship to cardiomyopathy is considered and the main morphological and aetiological factors are presented.

Possible role of prostaglandins in the pathogenesis of cardiomyopathies

Alcohol, adriamycin, viruses and excess deposition of iron in the heart are known to induce cardiomyopathy. Altered immune response in the form of defective T cell function, overactive anti-body-producing B lymphocytes and circulating anti-heart antibodies; increased fibrous tissue in the heart, with a tendency to develop mural thrombi, arrhythmias and cardiac failure are some of the important features observed in these cases. Prostaglandins can modify immune response, regulate fibrous tissue and collagen biosynthesis, are believed to be involved in the pathogenesis of cardiac arrhythmias and failure. Ethanol, adriamycin, viruses and iron are known to alter prostaglandin(PG) synthesis. The altered PG function may play a major role in cardiomyopathy.

Autoimmune studies in patients with primary myocardial disease

Heart immunofluorescent autoantibody tests, the complement fixation test for Chagas' disease, the hemagglutination test for toxoplasmosis, and the latex flocculation test for rheumatoid disease were compared in 34 patients with primary myocardial disease and their paired control subjects. There was no difference in the incidence of elevated titers or in the actual titer levels between the group with primary myocardial disease and the control group for any of these tests.

This study is limited in that it gives no information about an agent or mechanism for primary myocardial disease which is no longer demonstrable by serological test, particularly since the patients with primary myocardial disease were studied, at an average, 6 years after onset of symptoms. It is also possible that agents or mechanisms other than those included in this study may be causative of primary myocardial disease.

We have, however, demonstrated that there is no serological evidence associating the parasites or immunological responses studied with the clinical syndrome of chronic primary myocardial disease.