A clinical trial of immunosuppressive therapy for myocarditis. The Myocarditis Treatment Trial Investigators

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.

Viral myocarditis and dilated cardiomyopathy: mechanisms, manifestations, and management

Viral infection of the heart is relatively common and usually of little consequence. It can, however, lead to substantial cardiac damage and severe acute heart failure. It can also evolve into the progressive syndrome of chronic heart failure. Recent studies have gone some way towards unravelling the complex mechanisms underlying the heart muscle damage that occurs after viral infection. These studies have lent support to both immune and viral mediated (independent of an immune response) cardiac damage. Acute myocarditis can present in various ways, and it may be a cause of sudden death in an otherwise healthy young adult. New treatments for viral heart disease are awaited. In the meanwhile, the haemodynamic support of patients with acute left ventricular failure caused by myocarditis should be aggressive, to allow for the possibility of spontaneous recovery. Contemporary trials of treatment in chronic heart failure secondary to dilated cardiomyopathy support the use of angiotensin converting enzyme inhibitors, beta adrenoceptor blockers, and spironolactone in such patients.

Prognostic significance of left ventricular aneurysms with normal global function caused by myocarditis

OBJECTIVES

To evaluate the prognosis of left ventricular (LV) aneurysms with normal global function caused by myocarditis.

BACKGROUND

LV aneurysms may result from idiopathic or viral myocarditis. The prognosis of inflammatory LV aneurysms when associated with a normal cardiac function is unknown.

METHODS

Among 353 patients with a histologic diagnosis of myocarditis, 12 (3.3%) had single or multiple localized LV aneurysms (length, 10.6 +/- 3.1 mm; width, 7.4 +/- 4.2 mm) with normal cardiac function. Presenting symptoms were ventricular tachycardia (VT) in nine patients and unexplained chest pain in three. All patients underwent laboratory tests and noninvasive and invasive cardiac examinations, including biventricular endomyocardial biopsy.

RESULTS

In all patients, LV endomyocardial biopsy specimen showed a lymphocytic myocarditis with focal intense myocytolysis or damage of intramural vessels, whereas right ventricular biopsy was diagnostic for myocarditis only in three. Serologic study suggested a viral infection in 3 patients and an immunologic disorder in 2, although it was negative in 7. Treatment included antiarrhythmics in 9 patients with VT, ss-blockers in 1 with chest pain, and immunosuppression (prednisone and azathioprine for 5 months) in 4 with active myocarditis (2 with chest pain and 2 with VT). At intermediate-term follow-up (mean, 53 months; range, 12 to 120 months), LV function was persistently normal in all patients, with an LV aneurysm occlusion being observed in two patients. All patients were asymptomatic, with no VT recurrence or major clinical events. None required implantable electrical devices or a surgical intervention.

CONCLUSIONS

LV aneurysms with normal global function caused by myocarditis are an uncommon benign entity in which major therapeutic regimens are usually unnecessary.

Nasal administration of cardiac myosin suppresses autoimmune myocarditis in mice

OBJECTIVES

This study was designed to examine whether myocarditis induced in a mouse model can be effectively suppressed by nasal administration of cardiac myosin (CM).

BACKGROUND

Myocarditis in humans often follows viral infection and is accompanied by evidence of an autoimmune response to CM. Treatment has been hampered by the fact that measures undertaken to reduce the autoimmune response often enhance the viral infection. Delivery of antigen via nasal route has been shown to induce antigen-specific tolerance and suppress certain autoimmune diseases in animal models.

METHODS

Myocarditis was induced in A/J mice by two subcutaneous injections of CM emulsified in complete Freund's adjuvant. Nasal instillation of CM (200 microg/mouse) or vehicle buffer was carried out three days before the first subcutaneous injection (day -3). The effect of nasal instillation of CM on cardiac histopathology, cytokine production by splenocytes, and antibody response was examined three weeks after the first subcutaneous injection (day 21).

RESULTS

Nasal administration of CM effectively reduced the severity of myocarditis. Consistent with the histological findings, the levels of interleukin-2 (IL-2), tumor necrosis factor-alpha, and IL-1beta produced by splenocytes in response to CM were significantly decreased. In addition, the serum levels of IgE and IgG1 anti-myosin antibodies were suppressed. However, the levels of transforming growth factor-beta (TGF-beta) and CM-specific IgA antibodies were not affected.

CONCLUSIONS

Taken together, our results do not support active suppression through upregulation of TGF-beta, IL-4, and IL-10 as a mechanism of tolerance, but favor anergy or deletion of both Th1 and Th2 autoreactive T cells.

Myocarditis

Myocarditis and its sequela, dilated cardiomyopathy (DCM), cause substantial morbidity and mortality, especially in children and young adults. Physicians should include myocarditis in the differential diagnosis of all patients who have new symptoms of heart failure, arrhythmia, or chest pain syndromes of unclear cause, and should strongly consider performing endomyocardial biopsy (EMB) to establish the diagnosis. It may be necessary to perform multiple or serial biopsies to increase sensitivity. Patients with myocarditis and symptomatic heart failure, chest pain, or arrhythmias need hospitalization for evaluation and treatment. Patients with symptomatic left ventricular dysfunction should be treated with conventional heart failure therapy, including angiotensin-converting enzyme (ACE) inhibitors, digitalis, diuretics, and beta-blockers. Patients with arrhythmias or syncope may require electrophysiologic evaluation. In addition to conventional therapy, physicians should consider a course of immunosuppressive therapy in selected patients. The clinical course, response to therapy, and left ventricular function need close monitoring. Patients with myocarditis and rapidly progressive heart failure or cardiogenic shock should be referred early to an advanced heart failure center for implantation of a ventricular assist device and consideration for cardiac transplantation.

Idiopathic Cardiomyopathy

Idiopathic cardiomyopathy is a very common cause of heart failure today. It is a diagnosis of exclusion, and careful attention should be paid to the patient history to exclude all other causes. ACE inhibitors have become the first line therapy for all classes of left ventricular dysfunction. Doses of all therapeutic drugs for CHF should be up-titrated to maximum targeted dosages. New agents are being developed that offer increasing hope for therapies that will alter the natural history of heart failure.

Myocarditis mimicking acute myocardial infarction: role of endomyocardial biopsy in the differential diagnosis

OBJECTIVE

To test the hypothesis, using endomyocardial biopsies, that unexplained cases of apparent acute myocardial infarction were caused by myocarditis.

MATERIAL

Between 1992 and 1998, 12 patients were admitted to the coronary care unit with severe chest pain, ST segment elevation, increased serum creatine kinase and MB isoenzyme, and with wall motion abnormalities on echocardiogram highly suggestive of acute myocardial infarction. These patients were further investigated by endomyocardial biopsy, as their coronary angiograms were normal. A diagnosis of myocarditis was made according to the Dallas criteria. A panel of antibodies was used for immunohistochemical characterisation of inflammatory cell infiltrate. Polymerase chain reaction (PCR) was used to detect viral genomes in seven cases.

RESULTS

Haematoxylin and eosin staining of the endomyocardial biopsy showed active myocarditis in six patients and borderline myocarditis in one. Immunohistochemistry was positive for inflammatory cell infiltrates in 11 patients, including all the seven who were positive on haematoxylin and eosin staining according to the Dallas criteria. Only one patient had no evidence of inflammation. PCR was positive in two patients, both for Epstein-Barr virus. Follow up showed complete resolution of echocardiographic abnormalities in all patients except one.

CONCLUSIONS

Myocarditis can mimic acute myocardial infarction in patients with angiographically normal coronary arteries, leading to errors of treatment. In patients with apparent myocardial infarction and a normal coronary angiogram, endomyocardial biopsy may help in the diagnosis of myocarditis. The sensitivity of endomyocardial biopsy was enhanced by using immunohistochemical and molecular biological techniques.

Difficult cases in heart failure: Effective treatment of severe acute myocarditis with intravenous immune globulin and pulse corticosteroids in a 32-year-old patient

We describe a 32-year-old patient with acute myocarditis resulting in severe heart failure with hemodynamic compromise who improved significantly after treatment with immune globulin and pulse steroids. Six weeks after termination of the immunosuppressive therapy the patient developed symptoms of heart failure again and his ejection fraction decreased to 30%-34%. Treatment with immune globulin resulted in resolution of symptoms and return of left ventricular function. (c)2000 by CHF, Inc.

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.

Molecular Aspects of Myocarditis

Myocarditis is an acquired form inflammatory heart muscle disease, manifested as acute and chronic conditions. While many etiologies have been reported, the most common cause of this disease is infection, primarily viral. Typically, the specific causative agent(s) and mechanism(s) are elusive. Over the past several years, various new findings have added to our understanding of myocarditis. These include the identification of adenoviruses as important causative agents, a new receptor protein likely to play an important role in the virulence of certain agents affecting the myocardium, and the effect of viruses on the cardiac cytoskeleton. This report reviews the current understanding of myocarditis, proposes a hypothesis about the long-term sequelae, and suggests possible new therapeutic strategies.

Mechanical bridge to recovery in fulminant myocarditis

A patient with acute fulminant lymphocytic myocarditis and cardiogenic shock was successfully treated by mechanical off loading of the left ventricle. A nonpulsatile left-heart bypass was undertaken with an implantable centrifugal blood pump. Careful weaning resulted in device removal on the seventh day. Left and right ventricular function is sustained at 7 months. Widespread application of this method depends on the availability of an inexpensive user friendly blood pump, appropriate weaning protocols and emerging strategies to promote sustainable myocardial recovery.

[Epstein-Barr virus. An unusual cause of acute myocarditis in children]

Epstein-Barr virus does not belong to the principal causative agents of acute myocarditis, whose diagnosis and pathogenesis are often difficult to determine. Treatment is also controversial regarding the use of anti-inflammatory or immunosuppressive therapy.

CASE REPORT

We describe a 13-month-old girl, admitted for acute heart failure, in whom cardiac catheterization with endomyocardial biopsy revealed an acute myocarditis. Acute viral titers indicated infectious mononucleosis caused by Epstein-Barr virus, and the virus genome was identified with a polymerase chain reaction in the patient's serum. The patient had clinical improvement after corticosteroid administration.

CONCLUSION

The different diagnostic tools and the screening examinations to determine the causative agent of myocarditis are discussed. The frequency of Epstein-Barr virus in pathogenesis is also considered. The favorable outcome with immunosuppressive therapy suggests its administration in cases of acute myocarditis.

Echocardiographic findings in fulminant and acute myocarditis

OBJECTIVES

We sought to use echocardiography to assess the presentation and potential for recovery of left ventricular (LV) function of patients with fulminant myocarditis compared with those with acute myocarditis.

BACKGROUND

The clinical course of patients with myocarditis remains poorly defined. We have previously proposed a classification that provides prognostic information in myocarditis patients. Fulminant myocarditis causes a distinct onset of illness and severe hemodynamic compromise, whereas acute myocarditis has an indistinct presentation, less severe hemodynamic compromise and a greater likelihood of progression to dilated cardiomyopathy.

METHODS

Echocardiography was performed at presentation and at six months to test the hypothesis that fulminant (n = 11) or acute (n = 43) myocarditis could be distinguished morphologically.

RESULTS

Patients with both fulminant (fractional shortening 19 +/- 4%) and acute myocarditis (17 +/- 7%) had LV systolic dysfunction. Patients with fulminant myocarditis had near normal LV diastolic dimensions (5.3 +/- 0.9 cm) but increased septal thickness (1.2 +/- 0.2 cm) at presentation, while those with acute myocarditis had increased diastolic dimensions (6.1 +/- 0.8 cm, p < 0.01 vs. fulminant) but normal septal thickness (1.0 +/- 0.1 cm, p = 0.01 vs. fulminant). At six months, patients with fulminant myocarditis had dramatic improvement in fractional shortening (30 +/- 8%) compared with no improvement in patients with acute myocarditis (19 +/- 7%, p < 0.01 for interaction between time and type of myocarditis).

CONCLUSIONS

Fulminant myocarditis is distinguishable from acute myocarditis by echocardiography. Patients with fulminant myocarditis exhibit a substantial improvement in ventricular function at six months compared with those with acute myocarditis. Echocardiography has value in classifying patients with myocarditis and may provide prognostic information.

Echocardiographic follow-up of Chlamydia psittaci myocarditis

Chlamydia psittaci myocarditis has been infrequently reported. A case of serologically confirmed C psittaci myocarditis with dilated left ventricle and severely impaired left ventricular function is described. Serial echocardiograms demonstrated complete recovery after therapy. An early diagnosis has important prognostic implications.

Long-term outcome of fulminant myocarditis as compared with acute (nonfulminant) myocarditis

BACKGROUND

Lymphocytic myocarditis causes left ventricular dysfunction that may be persistent or reversible. There are no clinical criteria that predict which patients will recover ventricular function and which cases will progress to dilated cardiomyopathy. We hypothesized that patients with fulminant myocarditis may have a better long-term prognosis than those with acute (nonfulminant) myocarditis.

METHODS

We identified 147 patients considered to have myocarditis according to the findings on endomyocardial biopsy and the Dallas histopathological criteria. Fulminant myocarditis was diagnosed on the basis of clinical features at presentation, including the presence of severe hemodynamic compromise, rapid onset of symptoms, and fever. Patients with acute myocarditis did not have these features. The incidence of the end point of this study, death or heart transplantation, was ascertained by contact with the patient or the patient's family or by a search of the National Death Index. The average period of follow-up was 5.6 years.

RESULTS

A total of 15 patients met the criteria for fulminant myocarditis, and 132 met the criteria for acute myocarditis. Among the patients with fulminant myocarditis, 93 percent were alive without having received a heart transplant 11 years after biopsy (95 percent confidence interval, 59 to 99 percent), as compared with only 45 percent of those with acute myocarditis (95 percent confidence interval, 30 to 58 percent; P=0.05 by the log-rank test). Fulminant myocarditis was an independent predictor of survival after adjustments were made for age, histopathological findings, and hemodynamic variables. The rate of transplantation-free survival did not differ significantly between the patients considered to have borderline myocarditis and those considered to have active myocarditis according to the Dallas histopathological criteria.

CONCLUSIONS

Fulminant myocarditis is a distinct clinical entity with an excellent long-term prognosis. Aggressive hemodynamic support is warranted for patients with this condition.

FTY720 prevents development of experimental autoimmune myocarditis through reduction of circulating lymphocytes

FTY720 is a new immunosuppressant agent and selectively decreases the number of circulating lymphocytes. In this study, we compared the effects of FTY720 with those of tacrolimus on experimental autoimmune myocarditis (EAM) in rats. A significant decrease in circulating lymphocyte counts was noted after a single administration of FTY720 in normal rats. At day 0, 7-week-old male Lewis rats were immunized with purified porcine cardiac myosin emulsified in complete Freund's adjuvant. FTY720 or tacrolimus was administered intraperitoneally daily. The number of myocarditis-affected areas in the FTY720 treatment groups with doses of 0.1 mg/kg/ day was significantly lower than those in control groups at days 14 and 28. In addition, at day 28, the myocarditis-affected areas in the FTY720 treatment group were significantly smaller than those in the tacrolimus treatment group receiving the same dose. Effects of early administration (days 0-10) and delayed administration (days 11-20) of FTY720 also were examined. At day 28, the myocarditis-affected areas in the early therapy group were significantly lower than those in the control group. In conclusion, we demonstrated that the development of EAM could be prevented by FTY720. These data also indicated that lymphocyte-mediated immunity is critically involved in the development of EAM.

[The clinical practice guidelines of the Sociedad Española de Cardiología on cardiomyopathies and myocarditis]

Myocardial diseases are a extraordinarily heterogeneous group of processes that only have in common the fact that they involve heart muscle and that they cause a wide spectrum of myocardial dysfunction. The approach of the management and treatment of the cardiomyopathies is a continuous matter of discussion because the vast majority of alternatives in this field have not been based on the best scientific possible evidence and, since except for the case of heart failure associated with dilated cardiomyopathy. The majority of different options have not been studied by means of large (or even small) randomized trials. Nevertheless, this chapter has tried to provide the reader with different approaches on how to deal with important clinical problems in dilated, hypertrophic and restrictive cardiomyopathies, and in myocarditis as well. For this, we have utilized the most relevant information found coupled with our best clinical judgment, although we admit that many of the clinical recommendations can be controversial.

Resuscitation from fulminant myocarditis associated with refractory ventricular fibrillation

Resuscitation was possible in a case of fulminant myocarditis with refractory ventricular fibrillation (Vf) using a percutaneous cardiopulmonary support system (PCPS). A 46-year old Japanese man suddenly experienced cardiopulmonary dysfunction shortly after the onset of flu symptoms, was promptly diagnosed as having fulminant myocarditis and PCPS was immediately initiated. On the second day in the hospital, refractory Vf occurred, which lasted for approximately 2h despite repeated efforts to terminate it. Finally, a large dose of steroids was administered. From the third day of hospitalization and onwards, the Vf disappeared totally. The patient completely recovered from such a serious state in 6 months. During the following 3 years, he has had no clinical symptoms of worsening. As in this case demonstrates, most myocarditis is curable and invasive measures are very helpful in rescuing patients from the fulminant type with refractory Vf.

C-reactive protein as a prognostic marker in lymphocytic myocarditis

The prognosis of patients with lymphocytic myocarditis (LM) is poor with the combined endpoint of death or transplant in the Myocarditis Treatment trial being 56% at 5 years. Physicians often have difficulty determining the prognosis in an individual patient. Patients with LM may have ongoing myocardial inflammation. We evaluated the ability of a serum marker of inflammation to predict prognosis in patients with LM. Serum concentrations of C-reactive protein (CRP) were measured in patients with LM. Thiry-one patients with clinical and histologic evidence of LM were evaluated. Patients with coronary artery disease, and idiopathic dilated and secondary cardiomyopathies were excluded. Overall mortality and morbidity from congestive heart failure was assessed at 28 days. The mean plasma CRP concentrations in the five patients who died within the 28-day follow-up period were significantly higher than in those patients who survived (17.4 +/- 5.6 vs 5.9 +/- 3.3 mg/ml, p < 0.05). The CRP concentration was positively correlated with plasma levels of lactic dehydrogenase and the New York Heart Association functional class. Routine measurement of CRP may be a useful tool for determining the prognosis in patients with LM.

Clinical outcomes of acute myocarditis in childhood

OBJECTIVE

To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis.

DESIGN

A retrospective review between November 1984 and February 1998.

SETTING

A major paediatric tertiary care hospital.

PATIENTS

36 patients with histologically confirmed lymphocytic myocarditis.

MAIN OUTCOME MEASURES

Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias.

RESULTS

Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2-131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0-28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity.

CONCLUSIONS

Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

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.

Intravenous immune globulin in the therapy of peripartum cardiomyopathy

OBJECTIVES

We sought to evaluate the effect of therapy with intravenous immune globulin on recovery of left ventricular function in women presenting with peripartum cardiomyopathy.

BACKGROUND

Peripartum cardiomyopathy is a rare complication of pregnancy that results in significant morbidity and mortality in women of childbearing age. Intravenous immune globulin has been reported to improve left ventricular systolic function in patients with acute dilated cardiomyopathy and myocarditis, but its effectiveness in peripartum cardiomyopathy is unknown.

METHODS

In this retrospective study, we compared the clinical outcomes of six women with peripartum cardiomyopathy treated with intravenous immune globulin (2 g/kg) with those of 11 recent historical control subjects. All women in the study were referred between 1991 and 1998 with class II to IV heart failure and a left ventricular ejection fraction of <0.40. Left ventricular ejection was reassessed during early follow-up (6.1+/-2.9 months).

RESULTS

The two groups did not differ in terms of baseline left ventricular ejection fraction, left ventricular end-diastolic diameter, months to presentation, age or multiparity. The improvement in left ventricular ejection fraction in patients treated with immune globulin was significantly greater than in the conventionally treated group (increase of 26+/-8 ejection fraction units vs. 13+/-13, p = 0.042).

CONCLUSIONS

In this small retrospective study of women with peripartum cardiomyopathy, patients treated with immune globulin had a greater improvement in ejection fraction during early follow-up than patients treated conventionally. Given the poor prognosis of women with peripartum cardiomyopathy who do not improve, this therapy merits further study.

Generation of humanized mice susceptible to peptide-induced inflammatory heart disease

BACKGROUND

Dilated cardiomyopathy (DCM) is a major cause of sudden cardiac death. In certain mouse major histocompatibility complex (MHC) backgrounds, myocarditis and inflammatory cardiomyopathy can be triggered by immunization with heart muscle-specific proteins. Similarly, chronic heart disease in humans has been linked to certain HLA alleles, such as HLA-DQ6. However, there is no experimental evidence showing that human MHC class II molecules and peptides derived from human proteins are involved in the pathogenesis of myocarditis and DCM.

METHODS AND RESULTS

We generated double CD4- and CD8-deficient mice transgenic for human CD4 (hCD4) and human HLA-DQ6 to specifically reconstitute the human CD4/DQ6 arm of the immune system in mice. Transgenic hCD4 and HLA-DQ6 expression rendered genetically resistant C57BL/6 mice susceptible to the induction of autoimmune myocarditis induced by immunization with cardiac myosin. Moreover, we identified heart-specific peptides derived from both mouse and human alpha-myosin heavy chains capable of inducing inflammatory heart disease in hCD4 and HLA-DQ6 double transgenic mice but not in hCD4 single transgenic littermates. The autoimmune inflammatory heart disease induced by the human heart muscle-specific peptide in hCD4 and HLA-DQ6 double transgenic mice shared functional and phenotypic features with the disease occurring in disease-susceptible nontransgenic mice.

CONCLUSIONS

Our data provide the first genetic and functional evidence that human MHC class II molecules and a human alpha-myosin heavy chain-derived peptide can cause inflammatory heart disease and suggest that human inflammatory cardiomyopathy can be caused by organ-specific autoimmunity. The humanized mice generated in this study will be an ideal animal model to further elucidate the pathogenesis of inflammatory heart disease and facilitate the development of rational treatment strategies.

Improved survival in patients with acute myocarditis using external pulsatile mechanical ventricular assistance

BACKGROUND

Acute myocarditis remains a disease with a variable clinical course, from full ventricular recovery to complete heart failure; to date, few cases have been reported that describe the efficacy of temporary mechanical ventricular assistance for its treatment.

METHODS

We evaluated the voluntary world registry with the use of an external pulsatile ventricular assist device (the ABIOMED BVS 5000 [BVS]) for acute myocarditis to determine the impact of mechanical ventricular assistance on outcome. Variables analyzed included patient demographics, serum chemistries, and overall hemodynamics prior to BVS, while on BVS support, and after BVS explanation. Postoperative parameters included re-operation, bleeding, respiratory failure, renal failure, and infections, neurologic, or embolic events.

RESULTS

Eighteen patients in the ABIOMED world registry underwent BVS implantation for myocarditis; 11 (61.1%) had complete pre-operative and hemodynamic data for analysis. Patients were supported for 13.2 +/- 17.0 days, after which time 7 (63.6%) patients survived to explanation of the device and 2 (18.2%) underwent transplantation. Elevated admission serum chemistries (blood ureanitrogen [BUN], creatinine, transaminases) and hemodynamics (central venous pressure [CVP], mean pulmonary arterial pressure [PAP], pulmonary capillary wedge pressure [PCW], cardiac index [CI], all normalized during the period of device support. Estimated ejection fractions in the 7 explanted patients ranged between 50 to 60% at routine evaluation 3 years after device removal.

CONCLUSIONS

Temporary mechanical ventricular assistance represents an efficacious therapy for acute myocarditis in patients with hemodynamic decompensation despite maximal medical therapy. Failure to achieve full ventricular recovery while on device support still allows for other surgical alternatives, including implantation of a long-term implantable ventricular assist device, or cardiac transplantation.

Pediatric myocardial disease

Cardiomyopathies are diseases of the heart muscles. This article reviews the causes, clinical presentation, diagnosis, management, and long-term outcomes of dilated and hypertrophic cardiomyopathy.

Global biventricular dysfunction in patients with asymptomatic coronary artery disease may be caused by myocarditis

BACKGROUND

The causal role of asymptomatic critical coronary artery obstruction in patients presenting with severe global biventricular dysfunction but no evidence of myocardial infarction is uncertain.

METHODS AND RESULTS

Among 291 patients aged >40 years undergoing a noninvasive (2-dimensional echocardiography) and invasive (catheterization, coronary angiography, and biventricular endomyocardial biopsy, 6 to 8 samples/patient) cardiac study because of progressive heart failure (New York Heart Association functional class III or IV) with global biventricular dysfunction and no history of myocardial ischemic events, 7 patients (2.4%; 7 men; mean age, 49+/-6.9 years) had severe coronary artery disease (3 vessels in 4 patients; 2 vessels in 1 patient, proximal occlusion of left anterior descending coronary artery in 2 patients). Left ventricular end-diastolic diameter and ejection fraction by 2-dimensional echocardiography were 73+/-10.5 mm and 23+/-6.5%, respectively, and right ventricular end-diastolic diameter and ejection fraction were 39+/-7 mm and 29+/-7.2%, respectively. Biopsy specimens showed extensive lymphocytic infiltrates with focal myocytolysis meeting the Dallas criteria for myocarditis in all patients (in 5 patients with and 2 patients without fibrosis). Cardiac autoantibodies were detected with indirect immunofluorescence in the serum of 2 patients with active myocarditis. The 2 patients with active inflammation received prednisone (1 mg. kg-1. d-1 for 4 weeks followed by 0.33 mg. kg-1. d-1 for 5 months) and azathioprine (2 mg. kg-1. d-1 for 5 months) in addition to conventional drug therapy for heart failure. At 8-month overall follow-up, cardiac volume and function improved considerably in immunosuppressed patients but remained unchanged in conventionally treated patients, of whom 1 died.

CONCLUSIONS

Global biventricular dysfunction in patients with severe asymptomatic coronary artery disease and no evidence of previous myocardial infarction may be caused by myocarditis. Histologic findings may influence the treatment.

From myocarditis to cardiomyopathy: mechanisms of inflammation and cell death: learning from the past for the future

A progression from viral myocarditis to dilated cardiomyopathy has long been hypothesized, but the actual extent of this progression has been uncertain. However, a causal link between viral myocarditis and dilated cardiomyopathy has become more evident than before with the tremendous developments in the molecular analyses of autopsy and endomyocardial biopsy specimens, new techniques of viral gene amplification, and modern immunology. The persistence of viral RNA in the myocardium beyond 90 days after inoculation, confirmed by the method of polymerase chain reaction, has given us new insights into the pathogenesis of dilated cardiomyopathy. Moreover, new knowledge of T-cell-mediated immune responses in murine viral myocarditis has contributed a great deal to the understanding of the mechanisms of ongoing disease processes. Apoptotic cell death may provide the third concept to explain the pathogenesis of dilated cardiomyopathy, in addition to persistent viral RNA in the heart tissue and an immune system-mediated mechanism. Beneficial effects of alpha1-adrenergic blocking agents, carteolol, verapamil, and ACE inhibitors have been shown clinically and experimentally in the treatment of viral myocarditis and dilated cardiomyopathy. Antiviral agents should be more extensively investigated for clinical use. The rather discouraging results obtained to date with immunosuppressive agents in the treatment of viral myocarditis indicated the importance of sparing neutralizing antibody production, which may be controlled by B cells, and raised the possibility of promising developments in immunomodulating therapy.

Myocardial inflammatory cell infiltrates in cases of dilated cardiomyopathy: light microscopic, immunohistochemical, and virological analyses of myocardium specimens obtained by partial left ventriculectomy

OBJECTIVE

Partial left ventriculectomy was introduced for the treatment of refractory dilated cardiomyopathy (DCM). To determine the presence and degree of inflammatory cell infiltrates in DCM and the correlation between the underlying myocardial injury and early clinical outcomes after the operation, we performed histopathological, immunohistochemical, and virological studies of the resected myocardium.

METHODS

Posterolateral walls of the left ventricle from 13 idiopathic DCM patients (9 males and 4 females; mean age = 53+/-14 years) were examined. Qualitative and quantitative analyses of the interstitial fibrosis and of the infiltrating inflammatory cells were conducted. For the immunohistochemistry, leukocyte surface markers and antibodies to adhesion molecules and cytokines were used. The histopathological findings were compared with the clinical results, including outcome within 1 year, and pre- and postoperative hemodynamic data. Genomic analysis of the myocardium with polymerase chain reaction was performed for enterovirus, mumps, influenza A, cytomegalovirus, and hepatitis C virus.

RESULTS

(1) The three patients who died of cardiac insufficiency after surgery had a higher count of infiltrating inflammatory cells than the eight survivors (32.1+/-10.4 vs 16.3+/-11.9 cells/mm2, p = 0.07). The severity of interstitial fibrosis (percent fibrosis) did not differ significantly between these two groups (28.3+/-15.0 vs 24.0+/-11.7%). (2) In patients who died of myocardial dysfunction, focal accumulations of lymphocytes were common, in which cytotoxic/suppressor T cells and helper/inducer T cells were observed. (3) Enterovirus genome was detected in the myocardium of two patients, both of them died after surgery.

CONCLUSIONS

Inflammatory cell infiltrates or active myocarditis appear in some cases to play an important role in the etiology and pathophysiology of clinically diagnosed DCM. There is a possibility that those patients with a more severe or ongoing inflammatory process might have poor outcomes after partial left ventriculectomy.

Enteroviral RNA replication in the myocardium of patients with left ventricular dysfunction and clinically suspected myocarditis

BACKGROUND

Previous studies dealing with the detection of enteroviral RNA in human endomyocardial biopsies have not differentiated between latent persistence of the enteroviral genome and active viral replication. Enteroviruses that are considered important factors for the development of myocarditis have a single-strand RNA genome of positive polarity that is transcribed by a virus-encoded RNA polymerase into a minus-strand mRNA during active viral replication. The synthesis of multiple copies of minus-strand enteroviral RNA therefore occurs only at sites of active viral replication but not in tissues with mere persistence of the viral genome.

METHODS AND RESULTS

We investigated enteroviral RNA replication versus enteroviral RNA persistence in endomyocardial biopsies of 45 patients with left ventricular dysfunction and clinically suspected myocarditis. Using reverse-transcriptase polymerase chain reaction in conjunction with Southern blot hybridization, we established a highly sensitive assay to specifically detect plus-strand versus minus-strand enteroviral RNA in the biopsies. Plus-strand enteroviral RNA was detected in endomyocardial biopsies of 18 (40%) of 45 patients, whereas minus-strand RNA as an indication of active enteroviral RNA replication was detected in only 10 (56%) of these 18 plus-strand-positive patients. Enteroviral RNA was not found in biopsies of the control group (n=26).

CONCLUSIONS

These data demonstrate that a significant fraction of patients with left ventricular dysfunction and clinically suspected myocarditis had active enteroviral RNA replication in their myocardium (22%). Differentiation between patients with active viral replication and latent viral persistence should be particularly important in future studies evaluating different therapeutic strategies. In addition, molecular genetic detection of enteroviral genome and differentiation between replicating versus persistent viruses is possible in a single endomyocardial biopsy.

111Indium antimyosin antibody imaging of primary myocardial involvement in systemic diseases

OBJECTIVE

The diagnosis of primary myocardial involvement in systemic diseases is clinically relevant but difficult in the absence of specific criteria. Whatever the underlying disease, myocytes degeneration is observed during the active phase of myocardial damage. The aim of this study was to assess the diagnostic value of scintigraphic imaging with 111Indium antimyosin antibody (AM), a specific marker of the damaged myocyte, for ongoing myocardial damage related to systemic diseases.

METHODS

40 patients with histologically confirmed systemic diseases were studied. They were classified into two groups according to the presence (group 1, n = 30), or the absence (group 2, n = 10) of clinical, electrocardiographic (ECG) or echocardiographic signs suggestive of myocardial involvement. Planar and tomographic acquisitions were obtained 48 hours after injection of AM (90 MBq). Rest 201thallium (T1) scintigraphy was also performed to assess myocardial perfusion and scarring. Clinical, ECG, and echocardiographic +/- scintigraphic evaluations were repeated during follow up (17 +/- 19 months) in 36 of 40 patients.

RESULTS

In group 1, 13 of 30 patients (43%) showed diffuse significant AM uptake throughout the left ventricle (LV), and no or mild T1 abnormality. Two of these were asymptomatic, four had normal ECG, and two had no clinical or echographic LV dysfunction. All patients in group 2 had negative AMA scintigraphy and normal T1 scintigraphy. During follow up of 12 AM positive patients, cardiac status improved after immunosuppressive treatment was intensified in nine cases, worsened in two cases, and remained stable in one. During follow up of 24 AM negative patients, cardiac status remained stable in 23 cases despite treatment not being increased in 20, including two patients with sequellary myocardial involvement. The last patient developed mild LV dysfunction after 36 months.

CONCLUSION

AM scintigraphy allows detection of active myocardial damage related to systemic diseases, with increased specificity compared with conventional methods, and increased sensitivity in some cases. Further studies are needed to assess the potential value of AM scintigraphy as a therapeutic guide.

Discordance between pre and post cardiac transplant diagnosis: implications for pre- and postoperative decision making

A correct clinical diagnosis in end-stage patients undergoing cardiac transplantation may have important prognostic and therapeutic implications. A retrospective clinico-pathologic study was carried out in 257 patients who had undergone cardiac transplantation at the University of Padua. A discrepancy between clinical and pathological diagnosis was found in 20 cases (8%). Among 126 patients with the clinical diagnosis of dilated cardiomyopathy, seven were found eventually to have ischemic heart disease (IHD), five myocarditis, one arrhythmogenic right ventricular cardiomyopathy (ARVC), and one non-compacted myocardium. Among the 87 patients with clinical diagnosis of IHD, three turned out to be dilated cardiomyopathy and one granulomatous myocarditis. Among the 10 patients with the clinical diagnosis of hypertrophic-restrictive cardiomyopathy, one had ARVC and one had cardiac fibroma. Altogether, only 24.5% underwent endomyocardial biopsy (EMB) and 75% coronary angiography before transplantation. Missed diagnosis of myocarditis occurred in patients in whom EMB was not carried out. EMB and coronary angiography might be indicated routinely in patients with apparent dilated cardiomyopathy, before proceeding to cardiectomy.

Low incidence of myocardial recovery after left ventricular assist device implantation in patients with chronic heart failure

BACKGROUND

Mechanical, histological, and biochemical improvement has been described in patients after left ventricular assist device (LVAD) support. Explantation of the LVADs without heart transplantation has been described in selected patients who received this therapy as a bridge to transplantation.

METHODS AND RESULTS

A retrospective review of patients receiving a mechanical bridge to transplantation at Columbia Presbyterian Hospital after July 21, 1991, was performed to determine the incidence of patients in whom the device was successfully explanted. From August 1, 1996, to February 1, 1998, we prospectively attempted to identify potential explant candidates by the use of exercise testing. During this time, we recruited 39 consecutive patients after insertion of the Thermo Cardiosystems vented electric device to participate in the following study. Approximately 3 months after device implantation, a maximal exercise test with hemodynamic monitoring and respiratory gas analysis was performed with the LVAD in the automated mode. The electric device was interfaced with a pneumatic console such that the rate could be decreased to 20 cycles/min. Hemodynamic measurements were recorded as the device rate was decreased. A repeat exercise test was then performed if the patient remained hemodynamically stable. A retrospective chart review of 111 LVAD recipients at our institution identified only 5 successful explant patients. Eighteen of the 39 patients were studied. Fifteen patients exercised with maximal device support. At peak exercise, VO2 averaged 14.5+/-3.6 mL. kg-1. min-1; LVAD flow, 8.0+/-1.3 L/min; Fick cardiac output, 11.4+/-3.3 L/min; and pulmonary capillary wedge pressure, 13+/-4 mm Hg. Seven patients remained normotensive and could exercise at a fixed rate of 20 cycles/min. In these patients, peak VO2 declined from 17.3+/-3.9 to 13.0+/-6.1 mL. kg-1. min-1. In one of these patients, the device was explanted.

CONCLUSIONS

Significant myocardial recovery after LVAD therapy in patients with end-stage congestive heart failure occurs in a small percentage of patients. Most of these patients have dilated cardiomyopathy. Exercise testing may be a useful modality to identify those patients in whom the device can be explanted.

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.

Myocarditis: a review

Myocarditis is the end result of a heterogeneous group of conditions which cause inflammation of the myocardium. The resulting myocardial dysfunction may be responsible for significant morbidity and reduced life expectancy of the survivors. The condition is difficult to diagnose and treatment is on the whole rather unsatisfactory. Further work is undoubtedly required to identify methods for early identification of the condition and to develop better therapies aimed at preventing progression to chronic heart failure.