Giant cell versus lymphocytic myocarditis. A comparison of their clinical features and long-term outcomes

Inhibition of progression of heart failure and expression of TGF-beta 1 mRNA in rats with heart failure by the ACE inhibitor quinapril

The cardioprotective effects of quinapril, an angiotensin-converting enzyme inhibitor, were studied in a rat model of heart failure. Twenty-six rats were divided into two groups: one given 20 mg/kg/day quinapril (n = 11), and controls given 0.5% methylcellulose (n = 15). After oral administration for 1 month, quinapril reduced heart weight (from 1.28+/-0.05 to 0.87+/-0.02 g; p < 0.05) without changing body weight. Quinapril lowered left ventricular end-diastolic pressure (from 14.1+/-2.0 to 6.6+/-1.5 mmHg; p < 0.05) and central venous pressure (from 2.7+/-0.9 to 0.7+/-0.4 mmHg), and increased +/- dP/dt (from +2409+/-50 to +3569+/-169 mmHg/s, and from -2318+/-235 to -3960+/-203 mmHg/s; both p < 0.01). The area of myocardial fibrosis was markedly reduced by quinapril (6+/-3%) as compared with controls (29+/-6%; p < 0.01). Expression of transforming growth factor (TGF)-beta1 mRNA was markedly increased in controls as compared with age-matched normal rats. The increase in level of TGF-beta1 mRNA was significantly suppressed by quinapril (from 17.1+/-6.2 to 9.00+/-2.40; p < 0.05). These observations indicated that quinapril has cardioprotective effects on heart failure, and that the beneficial effects may be partly explained by attenuation of fibrotic response through suppression of TGF-beta1 mRNA expression.

Acute effects of endothelin-1 and TAK-044 (ET(A) and ET(B) receptor antagonist) in rats with dilated cardiomyopathy

The hemodynamic effects of endothelin (ET)-1 and TAK-044 (ET(A) and ET(B) receptor antagonist) were studied in a rat model of dilated cardiomyopathy after autoimmune myocarditis. Six weeks after immunization, survived Lewis rats (30/43 = 70%) were randomly allocated into five groups to be given 0, 0.3, 3, 30 and 60 mg/kg/day (groups F0, F0.3, F3, F30 and F60; each group, n = 4) of TAK-044 using an osmotic pump subcutaneously. Age-matched normal Lewis rats (n = 26) were also randomly divided into four groups to be given 0, 0.3, 3 and 30 mg/kg/day (groups N0, N0.3, N3 and N30; each group, n = 4). ET-1 concentrations in plasma and myocardium were measured, and immunohistochemical detection of ET-1 in the left ventricle from the remaining rats (groups F and N) was performed. After administration of TAK-044 for 7 days, 2, 4, 11, 21 and 42 ng/min ET-1 every 20 min was infused using a pump, and the change in mean arterial pressure of each group during the infusion was examined. The plasma and myocardial ET-1 concentrations were significantly higher in group F than group N (12.3 +/- 1.5 vs. 5.4 +/- 0.2 pg/ml and 426 +/- 31 vs. 98 +/- 6 pg/g tissue; both p < 0.01). Strong positive signals for ET-1 were found to be widely distributed in the left ventricular myocardium of both groups of rats. Although the ET-1-induced increase in the mean arterial pressure was abolished in group N30, the maximal dose of ET-1 produced a 34% increase in the mean arterial pressure in group F30. Even in group F60, ET-1-induced hypertension was blocked incompletely. These results indicate that the heart may be a major ET-1-producing organ, and a higher dose of ET-1 antagonist is needed to block the effect of ET-1 in rats with dilated cardiomyopathy.

Etiology, evaluation, and management of acute myocarditis

The evaluation and management of acute myocarditis remain two of the most difficult challenges that general internists and cardiologists face today. Although the majority of cases are subclinical and self-limited, the true prevalence of myocarditis in the general population is unknown. In its most severe form, patients with myocarditis may present with rapidly progressive heart failure, cardiogenic shock, or complex arrhythmia. Indeed, acute myocarditis should be in the differential diagnosis of acute heart failure, particularly in young and previously healthy individuals.

Sarcoidosis and the Heart

The treatment of sarcoid cardiomyopathy can be considered in part the treatment of the systemic disorder, and in part cardiac involvement, the manifestations of which may differ greatly. Therapy for the systemic disease is corticosteroid. Therapy for cardiac involvement includes prednisone, but because treatment must ameliorate or abolish many differing manifestations, therapy differs among patients. Asymptomatic patients (the majority) who are free from serious manifestations of the disease do not require pharmacologic or interventional treatment. Patients with dilated cardiomyopathy require treatment for congestive heart failure. High-grade atrioventricular conduction delay usually necessitates a permanent electronic pacemaker. Life-threatening arrhythmia usually requires implantation of an automatic implantable cardiac defibrillator (AICD). Antiarrhythmic drugs may also be needed. Cardiac tamponade should be treated by drainage of pericardial fluid. Pericardiectomy is usually the appropriate treatment for patients who develop significant constrictive pericarditis. Calcium channel blockers may be helpful for severe diastolic dysfunction that occurs in those with restrictive cardiomyopathy. Therapy should be given to those few patients who manifest hypertrophic cardiomyopathy to relieve left ventricular outflow obstruction. Cardiac transplantation for intractable heart failure or arrhythmia may be needed.

Survival outcomes of patients with giant cell myocarditis bridged by ventricular assist devices

Giant cell myocarditis is a highly lethal disorder characterized by rapidly progressive congestive heart failure. The aim of this study was to describe the clinical course of patients with giant cell myocarditis who received a ventricular assist device. Patients with giant cell myocarditis were identified from the Multicenter Giant cell Myocarditis Registry. Bridging to cardiac transplantation in the giant cell myocarditis patients who received a ventricular assist device was compared with bridging in the general population of heart failure patients, as reported in the literature. Median posttransplantation survival for patients with giant cell myocarditis who received and did not receive ventricular assist devices was calculated by the Kaplan-Meier method and compared with use of the log-rank test. Nine patients with giant cell myocarditis who received ventricular assist devices were identified. Seven patients survived to transplantation, four were alive 30 days posttransplantation, and two survived to 1 year. The rate of successful bridging to transplantation in seven of nine patients (78%) is similar to that reported for other ventricular assist device recipients. Posttransplantation survival of 57% (4 of 7) at 30 days and 29% (2 of 7) at 1 year was significantly lower compared with 93% 1-year survival of the 30 patients with giant cell myocarditis who did not receive ventricular assist devices before transplantation (p<0.001). Ventricular assist devices can be an effective bridge to transplantation for patients with heart failure caused by giant cell myocarditis. Although their posttransplantation survival was poor in our series, a few patients had long-term survival.

Low dose carvedilol inhibits progression of heart failure in rats with dilated cardiomyopathy

The cardioprotective properties of carvedilol (a vasodilating beta-adrenoceptor blocking agent) were studied in a rat model of dilated cardiomyopathy induced by autoimmune myocarditis. Twenty-eight days after immunization, surviving Lewis rats (32/43=74%) were divided into three groups to be given 2 mg kg(-1) day(-1) (Group-C2, n=10) or 20 mg kg(-1) day(-1) (Group-C20, n=10) of carvedilol, or vehicle (0.5% methylcellulose, Group-V, n=12). After oral administration for 2 months, body weight, heart weight (HW), heart rate (HR), rat alpha-atrial natriuretic peptide (r-ANP) in blood, central venous pressure (CVP), mean blood pressure (mean BP), peak left ventricular pressure (LVP), left ventricular end-diastolic pressure (LVEDP), +/-dP dt(-1) and area of myocardial fibrosis were measured. Values were compared with those for normal Lewis rats (Group-N, n=10). Two out of 12 (17%) rats in Group-V died from day 28 to day 42 after immunization. No rat died in Groups-C2, -C20 and -N. Although the CVP, mean BP, LVP and +/-dP dt(-1) did not differ among the three groups, the HW, HR and r-ANP in Group-C2 (1.14+/-0.03, 339+/-16 and 135+/-31) and Group-C20 (1.23+/-0.04, 305+/-8 and 156+/-24) were significantly lower than those in Group-V (1.36+/-0.04 g, 389+/-9 beats min(-1) and 375+/-31 pg ml(-1), respectively). The LVEDP in Group-C2 was significantly lower than that in Group-V (7.4+/-1.4 and 12.2+/-1.2 mmHg, respectively, P<0. 05). The area of myocardial fibrosis in Group-C2 was smaller than that in Group-V (12+/-1 and 31+/-2%, P<0.01). These results indicate that a low dose of carvedilol has beneficial effects on dilated cardiomyopathy.

Giant cell myocarditis: most fatal of autoimmune diseases

OBJECTIVE

To increase awareness of giant cell myocarditis (GCM), its pathogenesis, and treatment.

METHODS

Review of relevant publications from the English-language literature.

RESULTS

GCM is a rare, frequently fatal inflammatory disorder of cardiac muscle of unknown origin, characterized by widespread degeneration and necrosis of myocardial fibers.Congestive heart failure and ventricular tachycardia are common clinical manifestations. GCM occurs primarily in previously healthy adults, although it is frequently associated with various systemic diseases, primarily of autoimmune causes. The inflammatory infiltrate is characterized by the presence of multinucleated giant cells and is distinct from cardiac sarcoidosis. Animal models of GCM are similar to models of other autoimmune disorders such as rheumatoid arthritis. The prognosis, which is poor despite partial responsiveness to immunosuppressive medications, is improved with cardiac transplantation.

CONCLUSIONS

The clinical and immunopathogenetic similarities with classical rheumatologic diseases, the differential diagnosis with sarcoidosis and other inflammatory conditions, and the use of standard immunosuppressive medications make GCM a disease process that should be added to the rheumatologist's expertise.

Combined immunosuppression for the treatment of idiopathic giant cell myocarditis

Giant cell myocarditis (GCM) is a rare and frequently fatal disorder with no proven treatment. Case reports and data from a rat model of GCM suggest that immunosuppressive therapy directed against T lymphocytes may have clinical benefit. We describe a 47-year-old man with severe acute heart failure due to GCM in whom the left ventricular ejection fraction normalized and the myocardial inflammatory infiltrate resolved rapidly after treatment with muromonab-CD3, cyclosporine, azathioprine, and corticosteroids. Three previously published cases with less impressive responses to treatment including muromonab-CD3 and a critical review of the published data on immunosuppressive therapy are included in this report. The response to immunosuppressive therapy is highly variable, and direct comparisons between immunosuppressive regimens do not exist. Therefore, despite individual reports of dramatic improvement after immunosuppressive treatment, firm conclusions cannot be made about the benefit of immunosuppression for GCM. The benefits of immunosuppressive therapy must be confirmed in a prospective, randomized trial.

The spectrum of dilated cardiomyopathy. The Johns Hopkins experience with 1,278 patients

This report describes the evaluation of 1,278 patients referred to The Johns Hopkins Hospital with dilated cardiomyopathy. After a careful history and physical examination, selected laboratory tests, and endomyocardial biopsy, a specific diagnosis was made in 49% of cases. In 16% of cases the biopsy demonstrated a specific histologic diagnosis. Myocarditis and coronary artery disease were the most frequent specific diagnoses; 51% of patients were classified as idiopathic. Thus a rigorous and systematic search can demonstrate an underlying cause for approximately one-half of patients with unexplained cardiomyopathy. Endomyocardial biopsy plays a crucial role in this evaluation. Six cases are presented which demonstrate the utility of endomyocardial biopsy in specific clinical situations. In addition to its routine use in monitoring rejection in heart transplant recipients, endomyocardial biopsy is indicated in the evaluation of possible infiltrative cardiomyopathy, in differentiating restrictive cardiomyopathy from constrictive pericarditis, and in diagnosing and monitoring doxorubicin cardiotoxicity. The importance of diagnosing myocarditis remains controversial, and disagreement persists about the utility of immunosuppressive therapy in these patients. A combination of clinical and histologic features can divide patients with myocarditis into 4 subgroups--acute, fulminant, chronic active, and chronic persistent. This classification provides prognostic information and may identify those patients who may respond to immunosuppression, as well as those likely to have adverse outcomes from such treatment. The continued development of novel molecular techniques may allow endomyocardial biopsy to provide greater prognostic and therapeutic information in the future.

A new scoring system to predict the efficacy of steroid therapy for patients with active myocarditis--a retrospective study

The efficacy of steroid therapy for active myocarditis is controversial, so a new scoring system was constructed based on 6 clinical parameters: (1) the mode of onset of the disease; (2) complications of immune-related systemic disorders; (3) evidence of viral infection; (4) the population of infiltrating inflammatory cells; (5) the appearance of multinucleated giant cells in endomyocardial biopsy specimens; and (6) the duration of active myocarditis. Points from -2 to +2 were assigned to each parameter and the total score was calculated from the 6 parameters. Twenty-one patients with clinically suspected myocarditis, who had been admitted to hospital from 1987, were retrospectively analyzed by this scoring system. Sixteen patients were treated without corticosteroids at presentation, and 5 patients were treated by conventional methods with adjunctive use of corticosteroids. In 10 patients of the non-steroid group myocarditis improved and their mean score was -4.8 at presentation. In 6 patients of the non-steroid group, myocarditis and cardiac symptoms persisted after initial therapy, and their score at presentation was -0.8. In 2 patients of the steroid group myocarditis improved after initial therapy and their score was +2. In 2 other patients of the steroid group, myocarditis and cardiac symptoms persisted and their score was +3. Another patient of the steroid group died from congestive heart failure and his score was -5 at presentation. In 8 of 9 patients with persistent myocarditis, the secondary phase therapy was challenged. Seven patients were treated with corticosteroids and 6 patients improved. Their score at the secondary phase was +2.5. Overall, non-steroid conventional treatment was successful in patients with the scores from -5 to -4, and steroid therapy succeeded in patients with scores from 0 to +6. Although this is a retrospective study, this scoring system is able to predict the efficacy of steroid therapy in patients with clinically suspected active myocarditis.

Idiopathic giant cell myocarditis after autologous hematopoietic stem cell transplantation and interleukin-2 immunotherapy: a case report

BACKGROUND

Interleukin-2 (IL-2) is used in the treatment of solid tumors and hematologic malignancies. Sudden death is a rare complication of IL-2 treatment.

METHODS

A patient with lymphoma underwent chemoradiotherapy myeloablation and autologous stem cell transplantation. The stem cells were cultured in IL-2 (6000 IU/mL) for 24 hours prior to infusion. After engraftment, treatment with IL-2 (1.8 x 10(6) IU/m2/day administered subcutaneously) was begun. After 4 days of treatment, the patient suddenly died. An autopsy was performed.

RESULTS

Histologic examination of the myocardium revealed a diffuse, lymphocytic infiltrate with scattered, multinucleated giant cells and foci of myocardial degeneration consistent with giant cell myocarditis. The lymphocytes were predominantly CD4 positive T cells, and the majority of these cells stained with antibodies for perforin, suggesting an unusual cytolytic role for these lymphocytes. DNA end-labeling of myocardial tissue sections revealed numerous apoptotic myocytes within the lymphocytic infiltrate.

CONCLUSIONS

To the authors' knowledge, this is the first report of giant cell myocarditis in association with high dose chemotherapy, transplantation, and IL-2 immunomodulation. The authors suggest that the cytokine imbalance produced by IL-2 may have initiated a preferential activation of T helper cells and an autoimmune phenomenon manifesting as giant cell myocarditis.

Recovery from complete atrioventricular block caused by idiopathic giant cell myocarditis after corticosteroid therapy

Giant cell myocarditis (GCM) is a rapidly progressive disease that leads to ventricular tachycardia or high-grade atrioventricular (A-V) block, frequently requiring a pacemaker. A 64-year-old woman developed syncope as a result of idiopathic GCM with A-V block. She required both a temporary and a permanent pacemaker. Two-dimensional echocardiography showed severely reduced wall motion. There was no histologic or clinical evidence to suggest sarcoidosis. Despite treatment with diuretics and an angiotensin-converting enzyme inhibitor, exertional dyspnea persisted. She received prednisolone 4 months after the onset of complete A-V block in the late phase of GCM. Prednisolone improved A-V nodal conduction in spite of the fact that there was no influence from LV wall motion, and sinus rhythm has continued for more than 2 years. In this patient, prednisolone was effective in the treatment of GCM.

Idiopathic giant-cell myocarditis--natural history and treatment. Multicenter Giant Cell Myocarditis Study Group Investigators

BACKGROUND

Idiopathic giant-cell myocarditis is a rare and frequently fatal disorder. We used a multicenter data base to define the natural history of giant-cell myocarditis and the effect of treatment.

METHODS

We identified 63 patients with idiopathic giant-cell myocarditis through journal announcements and direct mailings to cardiovascular centers worldwide.

RESULTS

The patients consisted of 33 men and 30 women with an average age of 42.6 years; 88 percent were white, 5 percent were black, 5 percent were Southeast Asian or Indian, and 2 percent were Middle Eastern. Most presented with congestive heart failure (47 patients, or 75 percent), ventricular arrhythmia (9 patients, or 14 percent), or heart block (3 patients, or 5 percent), although in some cases the initial symptoms resembled those of acute myocardial infarction (4 patients). Nineteen percent had associated autoimmune disorders. The rate of survival was worse than among 111 patients with lymphocytic myocarditis in the Myocarditis Treatment Trial (P<0.001); among our patients, the rate of death or cardiac transplantation was 89 percent, and median survival was only 5.5 months from the onset of symptoms. The 22 patients treated with corticosteroids and cyclosporine, azathioprine, or both therapies survived for an average of 12.3 months, as compared with an average of 3.0 months for the 30 patients who received no immunosuppressive therapy (P=0.001). Of the 34 patients who underwent heart transplantation, 9 (26 percent) had a giant-cell infiltrate in the transplanted heart and 1 died of recurrent giant-cell myocarditis.

CONCLUSIONS

Giant-cell myocarditis is a disease of relatively young, predominantly healthy adults. Patients usually die of heart failure and ventricular arrhythmia unless cardiac transplantation is performed. Despite the possibility of fatal disease recurrence, transplantation is the treatment of choice for most patients.

Inflammatory cardiomyopathy. The controversy of diagnosis and management

This article reviews the theories regarding the causes of lymphocytic myocarditis, including viral and immunologic (cellular versus humoral) causes. Also covered is the relationship of dilated cardiomyopathy to myocarditis, the familial predilection for dilated cardiomyopathy in some cases, shortcomings of the various modalities for diagnosing lymphocytic myocarditis, and the occurrence of lymphocytic myocarditis in association with systemic illnesses. Lastly, treatment options for myocarditis are explored.

Inflammatory myocardial diseases and cardiomyopathies

Inflammatory myocardial disease has been associated with a variety of infectious and noninfectious etiologies. It is associated with the development of dilated cardiomyopathy in some patients. Given its imprecise diagnosis, varied clinical presentation and undefined natural history, it is quite difficult to make broad generalizations regarding its evaluation and treatment. It is hoped continued application of new molecular biological and other techniques will shed further light on the pathophysiologic mechanisms of myocarditis in humans, thus pointing to therapeutic interventions.

Cardiac sarcoidosis: diagnostic, prognostic, and therapeutic considerations

Cardiac involvement in patients with sarcoidosis is an important consideration for those who are concerned with this strange disease. Sarcoidosis is not an acute malignant disease but may be noticed at the time of sudden, expected death as fatal myocardial sarcoidosis at autopsy. Even with modern advances in our ability to diagnose heart disease, cardiac sarcoidosis is still often overlooked because of its subclinical disease progression. In view of this, an extensive review of previously published literature and of our own case analyses has been carried out because of the authors' long-term experience with performing Konno's endomyocardial biopsy, which was originally developed in 1962 at the author's institution. However, the sensitivity of endomyocardial biopsy in detecting sarcoid granuloma is low (20-30%), and, instead, various kinds of nongranulomatous pathologies are often seen. During the course of our research it was found that there might exist a racial difference in cardiac sarcoidosis. Cardiac death was much more frequent in Japanese patients. The possibility that heart disease in sarcoidosis is caused by cor pulmonale due to advanced pulmonary fibrosis should be reevaluated because only a limited amount of background data is available. The author's review clarified the fact that cardiac sarcoidosis is caused by myocardial or pericardial involvement, resulting in various kinds of bradyarrhythmias or tachyarrhythmias and/or congestive heart failure. Electrocardiographic (ECG) and Holter monitor readings provide a simple and effective method for early detection of this disease. The incidence of ECG abnormalities in a total of 963 sarcoidosis patients was 22.1%, which was more frequent than that of the sex- and age-matched healthy control subjects (17.9%; p < 0.025). Echocardiography and radionuclide studies also provide useful clinical information. Careful follow-up and early corticosteroid administration followed by small maintenance doses may prevent the progression of the disease and improve prognosis. Owing to the progress in antiarrhythmic drugs and pacemaker implantation, the primary cause of death in cardiac sarcoidosis has changed from sudden death (1976 report) to congestive heart failure (1985 report).

Severe postcardiac-transplant rejection associated with recurrence of giant cell myocarditis

Giant cell myocarditis is a disease of unknown etiology with several controversial aspects: clinical course, therapeutic management, recurring risk after heart transplantation, and histopathological factors. We report a case of giant cell myocarditis that recurred after orthotopic heart transplantation and an uneventful postoperative period. The myocardial inflammatory process in this patient showed various evolutive phases: an acute onset of diffuse giant cell myocarditis, an evolution into a granulomatous form of inflammation within the explanted heart, and a recurrence with multiple giant cell inflammatory infiltrates in the transplanted heart. Moreover, the patient presented a severe clinical course after surgery with precocious and continuous acute rejections despite the repeated immunosuppressive treatments. In this article we discuss the morphological aspects of the disease and the postoperative course of this case in relation to the possible immune dysregulation of patients affected by myocarditis before heart transplantation.

Infectious and lymphocytic myocarditis: epidemiology and factors relevant to sports medicine

Myocarditis is a disease entity of permanent actuality and of special concern in the sports setting. This is because the probability of complications or sequelae increases if exercise is imposed. Myocarditis may pass unrecognized by the sufferer or be easily overlooked by the physician, especially in athletes, where electrocardiographic changes often exist normally. Furthermore, although the immune system of the conditioned individual may be more efficient than that of the sedentary individual, very strenuous and frequently repeated or long-lasting exercise may cause immunosuppression and an increased susceptibility to respiratory tract infections (RTI). Several causative agents of RTI can give rise to myocarditis as well. The true incidence of proven infectious myocarditis in society is unknown. Histopathologically defined myocarditis (lymphocytic myocarditis), on the other hand, has been found in about 1% of unselected routine autopsies. In general, the long-term prognosis in myocarditis is favorable but exercise stress may cause long-term sequelae or sudden death. It is thus essential to refrain from strenuous exercise during RTI.

Right ventricular dysfunction: an independent predictor of adverse outcome in patients with myocarditis

To assess the predictive value of right ventricular systolic function in patients with active myocarditis, the echocardiograms of 23 patients with biopsy-confirmed myocarditis were reviewed. Right ventricular systolic function was evaluated qualitatively and quantitatively by descent of the right ventricular base. Patients were divided into those with normal right ventricular function, in whom right ventricular descent was 1.9 +/- 0.1 cm, and those with abnormal right ventricular function, in whom right ventricular descent was 0.8 +/- 0.1 cm (p < 0.001). There were no differences between the two groups in age, duration of symptoms, baseline hemodynamics, or histologic assessment. Initial left ventricular ejection fraction was significantly lower in patients with depressed right ventricular function (27.5 +/- 4.9%) compared with that in patients with normal right ventricular function (47.5 +/- 6.3%) (p = 0.01). The likelihood of an adverse outcome, defined as death or need for cardiac transplantation, was greater in patients with abnormal right ventricular function (right ventricular descent < or = 1.7 cm) than in patients with normal right ventricular function (right ventricular descent > 1.7 cm) (p < 0.03). Multivariate analysis revealed that right ventricular dysfunction as quantified by right ventricular descent was the most powerful predictor of adverse outcome.

Orbital polymyositis and giant cell myocarditis

BACKGROUND

Orbital polymyositis associated with giant cell myocarditis rarely has been reported in the literature. The authors report the clinical, neuroradiographic, and histopathologic features of the only patient to survive this usually fatal syndrome after cardiac transplantation.

FINDINGS

This 22-year-old white woman presented in 1991 with periorbital redness, swelling, and pain in both eyes that was unresponsive to antibiotic therapy. Results of her examination were significant for limited extraocular movements, ptosis, erythema, edema, chemosis, and exophthalmos. Electrocardiogram and chest x-ray were normal. Orbital computed tomographic scan showed swelling of the extraocular muscles up to and including their insertions. The patient was given the diagnosis of orbital polymyositis and her condition improved clinically and radiographically while taking parenteral steroids. One month after discharge, the patient was in cardiogenic shock. Endomyocardial biopsy showed giant cell myocarditis, and the patient underwent emergent cardiac transplantation. Despite a complicated postoperative course, the patient has done remarkably well.

CONCLUSION

Although this disorder is rare, this case suggests the need for a high index of suspicion for giant cell myocarditis in patients with inflammatory orbital polymyositis. In non-Graves orbital polymyositis the patient should be questioned and instructed concerning the signs and symptoms of congestive heart failure. Chest x-ray, Holter monitoring, and electrocardiogram also should be performed and be repeated with an echocardiogram if there are any cardiac symptoms. In addition, early endomyocardial biopsy should be considered in the proper clinical setting, allowing timely diagnosis and expeditious cardiac transplantation.

Immune mechanisms of cardiac disease

It is evident that cellular infiltration can affect cardiac structure and function in a variety of disease states. Myocardial contractility can be impaired by cell-mediated injury or local release of cytokines. The study of immune cardiac disease has entered a period of rapid expansion that should be characterized by delineation of the mechanisms by which immune cells and factors localize in the myocardium, modulate myocyte function, and remodel myocardial architecture (Fig. 2). This new knowledge should result in the ability to target specifically both the pathways by which cardiac contractility is impaired by chronic inflammation and the sustained immune reactivity to cardiac antigens that underlies chronic myocardial inflammation. Nonspecific therapeutic interventions directed at congestive heart failure, currently the only acceptable approach to the treatment of immune myocarditis, should then serve a more ancillary function in the context of the use of rationally designed drugs. Such drugs could, for example, be specifically targeted to inhibiting the trafficking of leukocytes into the heart or the effects of their subsequent activation within the myocardium.

FK506 therapy of experimental autoimmune myocarditis after onset of the disease

Preventive effects of FK506 on autoimmune myocarditis have been demonstrated, but the therapeutic efficacy of the agent in established myocarditis yet remains to be assessed. In this study, effects of FK506 on experimental autoimmune myocarditis were investigated by the use of the agent after the onset of the disease. Lewis rats were immunized with either cardiac myosin or bovine serum albumin (BSA) in complete Freund's adjuvant. The onset of the disease was ascertained by examining randomly chosen cardiac myosin-immunized rats. Animals were divided into four groups: the BSA-immunized saline-treated group (group A, n = 6); the BSA-immunized FK506-treated group (group B, n = 6); the myosin-immunized saline-treated group (group C, n = 6); and the myosin-immunized FK506-treated group (group D, n = 11). Saline or 1.0 mg/kg/day of FK506 were intramuscularly injected from day 16 to day 27. All the rats were put to death on day 28. Rats of group C became severely ill by the third week, while in contrast, rats of group D remained active, as did rats of groups A and B. The heart weight/body weight ratio was significantly lower in group D than in group C rats. Group mean values were 3.48 +/- 0.10 gm/kg for group A, 3.48 +/- 0.16 gm/kg for group B, 4.94 +/- 0.66 gm/kg for group C, and 3.88 +/- 0.43 gm/kg for group D. Rats of group C showed severe myocarditis with mononuclear cell infiltration, myocardial necrosis, and interstitial edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cyclosporine, prednisolone and aspirin on rat autoimmune giant cell myocarditis

OBJECTIVES

Preventive effects of cyclosporine, prednisolone and aspirin on autoimmune giant cell myocarditis in rats were investigated.

BACKGROUND

The therapeutic efficacy of immunosuppressants for human myocarditis is controversial. Although harmful effects of immunosuppressive therapy on experimental viral myocarditis have been reported, the effects on autoimmune myocarditis have not been investigated. Recently, a novel experimental autoimmune myocarditis model characterized by congestive heart failure and multinucleated giant cell has been established. Using this model, the preventive effects of cyclosporine, prednisolone and aspirin on autoimmune myocarditis were investigated.

METHODS

Lewis rats were immunized with cardiac myosin in complete Freund's adjuvant on days 0 and 7. In experiment 1, four groups of seven rats each were established. Rats in each group received for 21 days intraperitoneal injections of either 1) phosphate-buffered saline solution, 1 ml/day (control); 2) cyclosporine, 20 mg/kg body weight per day (cyclosporine 20); 3) prednisolone, 4 mg/kg per day; or 4) aspirin, 15 mg/kg per day. In experiment 2, two additional groups (five rats each) received for 21 days an injection of cyclosporine, 1 or 5 mg/kg per day (cyclosporine 1 and cyclosporine 5, respectively). All rats were killed on day 21, when histopathologic studies were performed and the titers of antimyosin antibodies were measured.

RESULTS

The rats in the control, prednisolone and aspirin groups became ill and immobile in week 3. In comparison, rats in the cyclosporine 5 and 20 groups were still active until death was induced. Heart weight/body weight, lung weight/body weight and liver weight/body weight ratios in the rats in the cyclosporine 5 and cyclosporine 20 groups were significantly lower than those in the control group, and no differences were detectable among rats in the control, prednisolone and aspirin groups. The rats in the latter three groups and the cyclosporine 1 groups showed severe myocarditis with multinucleated giant cells. However, myocarditis was effectively prevented in the rats in the cyclosporine 5 and 20 groups. The histologic scores in each group were 2.91 in the control group, 2.14 in the prednisolone group, 2.91 in the aspirin group and 0.02, 2.58 and 0.07, respectively, in the cyclosporine 20, 1 and 5 groups. Production of antimyosin antibodies was remarkably suppressed in rats in the cyclosporine 5 and 20 groups in comparison with values in all other groups.

CONCLUSIONS

Autoimmune myocarditis is preventable by cyclosporine but not by prednisolone or aspirin in usual dosages.

Immunohistochemical characterization of infiltrating mononuclear cells in the rat heart with experimental autoimmune giant cell myocarditis

The pathogenesis of giant cell myocarditis remains unclear. Subsets of inflammatory infiltrating cells may reflect the pathogenesis and etiology of the disease. Therefore, we examined subsets of infiltrating mononuclear cells in the heart of the rat with experimental giant cell myocarditis. Lewis rats were immunized with cardiac myosin in Freund's complete adjuvant (FCA). Severe myocarditis characterized by congestive heart failure and multinucleated giant cells were elicited. The lesions were composed of predominant mononuclear cells, polymorphonuclear neutrophils and fragments of degenerated myocardial fibres. The subsets of infiltrating mononuclear cells were investigated using MoAbs against rat CD4+ T cell (W3/25), CD8+ T cell (CX8), B cell (OX33) and macrophage (OX42). By serial examination, bound immunoglobulin could only be found on degenerated myocardial fibres. In this model, most infiltrating mononuclear cells were composed of macrophages and CD4+ T cells. The frequencies of macrophages and CD4+ T cells were 73.7% and 13.8%, respectively. CD8+ T cells were scarce and B cells were rare in the lesions. The frequencies of CD8+ T cells and B cells were 4.5% and 0.4%, respectively. The dominance of macrophages and CD4+ T cells was the constant finding among the sites of the lesions and throughout the course of the disease. These characteristic subsets of infiltrating cells were in contrast to those of murine viral myocarditis which were mainly composed of natural killer (NK) cells and CD8+ T cells. Clarifying the subsets of infiltrating cells in myocarditis may contribute to differential diagnosis of myocarditis between viral and autoimmune types. From this study, the pathogenesis of experimental autoimmune giant cell myocarditis seemed to be closely related to CD4+ T cells and macrophages.

Clinicopathologic description of myocarditis

Histologic evidence of myocarditis was demonstrated in 35 of 348 patients submitted to endomyocardial biopsy over 5 years. Analysis of the histologic findings and clinical course of these patients resulted in a new clinicopathologic classification of myocarditis in which four distinct subgroups are identified. Patients with fulminant myocarditis become acutely ill after a distinct viral prodrome, have severe cardiovascular compromise, multiple foci of active myocarditis by histologic study and ventricular dysfunction that either resolves spontaneously or results in death. Patients with acute, chronic active and chronic persistent myocarditis have a less distinct onset of illness. Patients with acute myocarditis present with established ventricular dysfunction and may respond to immunosuppressive therapy or their condition may progress to dilated cardiomyopathy. Those with chronic active myocarditis initially respond to immunosuppressive therapy, but they have clinical and histologic relapses and develop ventricular dysfunction associated with chronic inflammatory changes including giant cells on histologic study. Chronic persistent myocarditis is characterized by a persistent histologic infiltrate, often with foci of myocyte necrosis but without ventricular dysfunction despite other cardiovascular symptoms such as chest pain or palpitation.