Myocarditis endomyocardial biopsy


 * Varun Kumar, M.B.B.S.

Overview
Endomyocardial biopsy remains the gold standard test to evaluate for the presence of and to subclassify the type of myocarditis. A small tissue sample of the endocardium and myocardium is obtained via right sided cardiac catheterization. The sample is then evaluated by a pathologist using immunochemistry and special staining techniques as necessary. Histopathological features include abundant edema in the myocardial interstitium and an inflammatory infiltrate which is rich in lymphocytes and macrophages. Focal destruction of myocytes as a result of the inflammatory process results in left ventricular dysfunction. Endomyocardial biopsy is recommended when the results would identify an underlying disease that is amenable to therapy. Routine performance of endomyocardial biopsy is not recommended in all patients with myocarditis.

Endomyocardial biopsy

 * The Heart Failure Society of America recommends that performance of endomyocardial biopsy should be considered when cardiac function deteriorates acutely with an unknown etiology that is unresponsive to medical therapy (Strength of Evidence = B).


 * Non-specific findings such as hypertrophy, cell loss and fibrosis may be noted on biopsy. However, biopsy findings that significantly impact patient management have not been conclusively established . For example, although inflammatory changes in the myocardium may be detected in viral myocarditis, the majority of patients with biopsy proven myocarditis improve with supportive therapy alone without the need for antiviral or anti-inflammatory treatment . Endomyocardial biopsy has a low sensitivity and specificity which could be explained by the focal and transient nature of the inflammatory infiltrates.

Standardizing the Interpretation of Endomyocardial Biopsies: The Dallas Criteria
Histologically, both active inflammatory infiltrate within the myocardium and associated myocyte necrosis (the Dallas pathologic criteria) are present in myocarditis. Despite its limitations, the Dallas criteria have established uniform histologic criteria diagnosing myocarditis and have substantially reduced the variability in diagnosing the disease. Some of the criteria are as follows: {{cquote|

Active myocarditis:

 * The presence of an inflammatory infiltrate of the myocardium with necrosis and/or degeneration of adjacent myocytes not typical of the ischaemic damage associated with coronary artery disease.

Borderline myocarditis:

 * The presence of an inflammatory infiltrate of the myocardium without necrosis or degeneration of adjacent myocytes.}}

Scenarios in Which Endomyocardial Biopsy May Be Useful

 * Subacute or acute symptoms of heart failure refractory to standard management
 * Rapid worsening of ejection fraction despite standard pharmacological therapy
 * Development of cardiac arrhythmias such as ventricular tachycardia and/or heart block
 * Heart failure with concomitant rash, fever, or peripheral eosinophilia
 * Cardiac dysfunction thought to be secondary to the following conditions as the results of endomyocardial biopsy may alter the therapy:
 * Collagen vascular disease:
 * Systemic lupus erythematosus
 * Scleroderma
 * Polyarteritis nodosum
 * Infiltrative diseases:
 * Amyloidosis: These patients are not eligible for cardiac transplantation
 * Sarcoidosis
 * Hemachromatosis
 * Giant cell myocarditisThese patients generally progress rapidly to either cardiac transplantation or death and are poorly responsive to treatment. Myocardial biopsy may optimize the management of these patients by identifying patients who may benefit from early heart transplantation ..

2009 ACC/AHA Guidelines- Endomyocardial Biopsy for Patients presenting with Heart Failure
{{cquote|

Class IIa
1. Endomyocardial biopsy can be useful in patients presenting with heart failure when a speciﬁc diagnosis is suspected that would inﬂuence therapy. (Level of Evidence: C)

Class III
1. Endomyocardial biopsy should not be performed in the routine evaluation of patients with heart failure. (Level of Evidence: C)}}

The AHA/ACCF/ESC Scientific Statement: The role of Endomyocardial Biopsy in fourteen clinical scenarios
{{cquote|

Class I
1. New-onset heart failure of less than 2 weeks’ duration associated with a normal-sized or dilated left ventricle and hemodynamic compromise. (Level of Evidence: B)

2. New-onset heart failure of 2 weeks’ to 3 months’ duration associated with a dilated left ventricle and new ventricular arrhythmias, second- or third-degree heart block, or failure to respond to usual care within 1 to 2 weeks. (Level of Evidence: B)

Class IIa
1. Heart failure of more than 3 months’ duration associated with a dilated left ventricle and new ventricular arrhythmias, second- or third-degree heart block, or failure to respond to usual care within 1 to 2 weeks. (Level of Evidence: C)

2. Heart failure associated with a dilated cardiomyopathy (DCM) of any duration associated with suspected allergic reaction and/or eosinophilia. (Level of Evidence: C)

3. Heart failure associated with suspected anthracycline cardiomyopathy. (Level of Evidence: C)

4. Heart failure associated with unexplained restrictive cardiomyopathy. (Level of Evidence: C)

5. Suspected cardiac tumors. (Level of Evidence: C)

6. Unexplained cardiomyopathy in children. (Level of Evidence: C)

Class IIb
1. New-onset heart failure of 2 weeks’ to 3 months’ duration associated with a dilated left ventricle, without new ventricular arrhythmias or second- or third-degree heart block, that responds to usual care within 1 to 2 weeks. (Level of Evidence: B)

2. Heart failure of more than 3 months’ duration associated with a dilated left ventricle, without new ventricular arrhythmias or second- or third-degree heart block, that responds to usual care within 1 to 2 weeks. (Level of Evidence: C)

3. Heart failure associated with unexplained hypertrophic cardiomyopathy (HCM). (Level of Evidence: C)

4. Suspected arrhythmogenic right ventricular dysplasia (ARVD/C). (Level of Evidence: C)

5. Unexplained ventricular arrhythmias. (Level of Evidence: C)

Class III
1. Unexplained atrial fibrillation. (Level of Evidence: C)}}

Complications of Endomyocardial Biopsy

 * Complications may be as high as 6% as observed in a series where 546 patients with cardiomyopathy underwent right ventricular endomyocardial biopsy . Several other studies reported the incidence of complications to be 0.5 to 1.5%.


 * Complications include:
 * Myocardial perforation leading to pericardial tamponade
 * Heart block
 * Pulmonary embolization
 * Pneumothorax
 * Nerve injury
 * Hematoma
 * Tricuspid valve damage
 * Arteriovenous fistula
 * Deep venous thrombosis
 * Bleeding at the puncture site (venous/arterial due to accidental arterial puncture)
 * Arrhythmias (supraventricular tachycardia/ventricular tachycardia/complete heart block)
 * Tricuspid valve damage
 * Coronary artery to right ventricle fistula

Guidelines Resources

 * 2009 focused update: ACCF/AHA Guidelines for the Diagnosis and Management of Heart Failure in Adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines: developed in collaboration with the International Society for Heart and Lung Transplantation


 * AHA/ACCF/ESC Scientific Statement: The Role of Endomyocardial Biopsy in the Management of Cardiovascular Disease