MYOCARDITIS Flashcards
What is myocarditis?
Inflammatory disease of the myocardium caused by external triggers (viruses, bacteria, etc.) or internal triggers (autoimmune activation).
Cardiac manifestations include acute heart failure, arrhythmias, and chronic dilated cardiomyopathy.
What are the four clinicopathologic forms of myocarditis?
- Fulminant myocarditis
- Acute myocarditis
- Chronic active myocarditis
- Chronic persistent myocarditis
What was the estimated incidence of myocarditis in 2019?
820,000 cases in males and 608,000 cases in females.
Estimated 32,449 deaths or 0.42 deaths per 100,000 in 2019.
What percentage of unexplained nonischemic dilated cardiomyopathy (DCM) cases is caused by myocarditis?
9% to 16%
In young athletes, what percentage of sudden deaths is attributed to myocarditis?
4% to 12%
What demographic factors influence the prevalence of myocarditis?
Higher prevalence and severity in men; peaks in the first year of life and between puberty and age 40.
What primary causes are associated with myocarditis?
- Viral infections
- Toxic triggers
- Noninfectious triggers
Which viruses are commonly associated with myocarditis?
- Coxsackievirus
- Adenovirus
- Parvovirus B19
- Human herpes virus 6
What is the role of COVID-19 in myocarditis cases?
20% to 35% of hospitalized COVID-19 patients showed evidence of myocardial injury.
What are some primary bacteria associated with myocarditis?
- Corynebacterium diphtheriae
- Streptococcus viridans
- Mycobacterium tuberculosis
What is hypersensitivity myocarditis?
An uncommon form of myocarditis due to adverse drug reactions, often resolving after medication withdrawal.
What is giant cell myocarditis (GCM)?
A rare autoimmune heart disease associated with poor prognosis and ventricular arrhythmias.
What are the three phases of viral myocarditis pathogenesis?
- Phase 1: Acute viral injury
- Phase 2: Subacute immune response
- Phase 3: Chronic myopathic
What are common clinical presentations of myocarditis?
- Viral prodrome
- Chest pain
- Palpitations
- Dyspnea
- Ventricular arrhythmias
What are the clinical phenotypes of myocarditis?
- Acute coronary syndrome mimic
- Myopericarditis
- New onset or worsening heart failure
- Life-threatening arrhythmias
What is the classification based on the level of diagnostic certainty?
- Possible subclinical acute myocarditis
- Probable acute myocarditis
- Definite myocarditis
What blood tests can guide the diagnosis of myocarditis?
- Inflammatory markers (ESR, CRP)
- Cardiac biomarkers (CK-MB, troponin I)
What noninvasive diagnostic tests are useful in myocarditis?
- ECG
- Echocardiography
- Cardiac magnetic resonance imaging (MRI)
What is the sensitivity of ECG in diagnosing myocarditis?
47%
What is the importance of cardiac MRI in myocarditis diagnosis?
Distinguishes ischemic from nonischemic cardiomyopathies and correlates with histological areas of viral myocarditis.
What is cardiac magnetic resonance imaging (MRI) used for?
To distinguish ischemic from nonischemic cardiomyopathies
Patterns of T1 postgadolinium delayed gadolinium enhancement (DGE) signal abnormality correlate with histological areas of viral myocarditis.
What do the Lake Louise Criteria recommend for diagnosing myocarditis?
Both T1- and T2-weighted sequences should be performed
These sequences also predict the risk of cardiovascular death and ventricular arrhythmias following myocarditis.
Is viral serology useful in diagnosing myocarditis?
No, it is limited due to low specificity
Antibody levels may wane over time and do not correlate with myocardial viral genomes determined by PCR.
What is giant cell myocarditis (GCM)?
A rare and progressive cause of acute heart failure that primarily affects young and otherwise healthy patients
It is associated with thymoma or autoimmune diseases in approximately 20% of cases.
How is GCM diagnosed?
By endomyocardial biopsy (EMB) demonstrating diffuse inflammation and necrosis with T-cell predominance
Associated with eosinophils, histiocytes, and multinucleated giant cells.
What is the role of endomyocardial biopsy (EMB) in myocarditis?
EMB remains the gold standard for diagnosis but is not indicated in all patients
High specificity but lower sensitivity due to sampling error.
How is an endomyocardial biopsy performed?
Access the right ventricle through the right internal jugular vein or right femoral vein
Fluoroscopy and/or echocardiography guidance are required to localize the site of biopsy.
What are the risks associated with an endomyocardial biopsy?
Complications reported in 1% to 6% of procedures
Serious complications such as ventricular perforation are less than 1%.
When is it appropriate to proceed with an endomyocardial biopsy?
In disorders that cannot be diagnosed by less invasive methods
AHA/ACC/ESC guidelines outline specific clinical scenarios for EMB consideration.
What are the limitations of the endomyocardial biopsy (EMB)?
Limited availability and low sensitivity
More than 17 samples may be required for 80% sensitivity.
What is the first-line therapy for myocarditis?
Supportive care and guideline-directed medical therapy for heart failure
Standard doses of beta-blockers, ACE inhibitors, and diuretics are recommended.
Should physical exercise be avoided in myocarditis?
Yes, continuous aerobic exercise increases mortality
Sustained aerobic physical activity should be avoided for a minimum of 3 months.
What are the predictors of mortality in myocarditis?
Syncope at presentation, greater ventricular systolic dysfunction, greater pulmonary hypertension, QRS >120 milliseconds, and Q waves in the ECG
Normal ventricular function is a predictor of good outcome.
Fill in the blank: The survival time for giant cell myocarditis (GCM) is typically less than ______.
4 months
True or False: Immunosuppressive therapy is routinely recommended for acute lymphocytic myocarditis.
False
