What virus is most commonly associated with cardiomyopathy (heart muscle disease)?

Viruses Most Commonly Associated with Cardiomyopathy

Enteroviruses (particularly Coxsackievirus B) and adenoviruses are the most commonly associated viruses with cardiomyopathy, though in recent years parvovirus B19 has emerged as a predominant pathogen in Western countries. 1

Viral Etiology of Cardiomyopathy

Common Viral Pathogens

• Historical predominance: Coxsackievirus B and other enteroviruses were the most common causes in the 1980s-1990s 1
• Current predominance:
  • Parvovirus B19 and human herpes virus 6 are now most frequent in Western Europe 1
  • Adenoviruses became predominant in the 1990s 1
  • Parvovirus B19 has more recently emerged as a leading cause 1

Regional Variations

• In North America and Western Europe: viral infections are the most commonly identified causes 1
• In specific world regions: Chagas disease, post-streptococcal rheumatic heart disease, and HIV are important causes 1
• In Asia: Diphtheria, typhoid fever, rubella, and even scorpion bite have been reported 1

Viral Detection in Cardiomyopathy

Multiple studies have identified various cardiotropic viruses in patients with myocarditis or dilated cardiomyopathy:

• Enteroviruses (especially Coxsackievirus B)
• Adenoviruses
• Parvovirus B19
• Human herpes virus 6
• Cytomegalovirus
• Epstein-Barr virus
• Influenza and respiratory syncytial virus
• Hepatitis C
• HIV 1, 2

Pathophysiology of Viral Cardiomyopathy

Mechanisms of Myocardial Damage

• Direct viral cytotoxicity: Viruses directly damage myocytes during replication 3
• Immune-mediated damage: Host immune response causes inflammation and myocardial injury 3
• Autoimmune response: Molecular mimicry between viral and cardiac antigens leads to ongoing damage 3

Disease Progression

1. Acute phase: Direct viral invasion and replication
2. Subacute phase: Immune-mediated inflammation
3. Chronic phase: Potential progression to dilated cardiomyopathy with or without persistent viral genome 2

Diagnosis of Viral Cardiomyopathy

Diagnostic Approach

• Endomyocardial biopsy (EMB) remains the gold standard for diagnosis of viral myocarditis and cardiomyopathy 1, 4
• PCR techniques on biopsy specimens can identify specific viral genomes 2
• Cardiac MRI is the most sensitive non-invasive test, showing edema and late gadolinium enhancement 4

When to Consider EMB

EMB is reasonable in:

• Unexplained cardiomyopathy in children 1
• New-onset heart failure of 2 weeks' to 3 months' duration with dilated left ventricle 1
• Suspected cardiac tumor or unexplained arrhythmias 1

Clinical Implications and Management

Prognostic Factors

• In children, viral etiology affects prognosis:
  • Adenovirus infections historically had worse outcomes (5-year survival rate of 66%) 1
  • Enterovirus-associated myocarditis may have better outcomes than other viral causes 1

Treatment Approaches

• Standard guideline-directed heart failure therapy for reduced ejection fraction 4
• Potential antiviral strategies (still investigational):
  • Pleconaril (inhibits virus uptake) 5
  • Interferons (antiviral and immunomodulating activities) 5
  • Soluble receptor analogues 5
  • RNA interference technologies 5

Special Considerations

Pediatric Population

• Viral myocarditis is a frequent cause of new-onset DCM in children 1
• Most common causes: enteroviruses, adenoviruses, and parvovirus B19 1
• Children with viral cardiomyopathy may have better survival than those with idiopathic DCM 1

Coinfection

Coinfection with ≥2 viruses occurs in a substantial minority of cases, potentially complicating diagnosis and treatment 1

Emerging Pathogens

SARS-CoV-2 (COVID-19) has emerged as a cause of myocarditis-like cardiac injury, with a hyperinflammatory response that can lead to myocardial damage 1

Pitfalls and Caveats

• Sampling error is common in EMB due to the focal nature of viral myocarditis 6
• Viral genome detection by PCR is highly sensitive but may not always correlate with active disease
• The absence of viral genome on EMB does not exclude viral etiology due to potential sampling error 1
• Viral prevalence has changed over time, so older literature may not reflect current epidemiology 1