Can HSV Cause Chronic Myocarditis?
Yes, herpes simplex virus (HSV) can cause chronic myocarditis, though it is less commonly identified than other viral pathogens in Western populations, and the progression from acute to chronic disease appears to occur through viral persistence in myocardial tissue.
Viral Etiology of Chronic Myocarditis
The American Heart Association identifies viral persistence after acute infection as the most common pathway to chronic myocarditis in developed countries, with viral genomes remaining detectable in myocardial tissue despite clearance of active viremia 1, 2. While HSV is recognized among the approximately two dozen viruses linked to myocarditis, it is not among the most frequently identified pathogens in chronic cases 1.
Most Common Viral Causes in Chronic Disease
- Parvovirus B19 and human herpes virus 6 (HHV-6) are the most frequently identified viruses in chronic myocarditis cases in Western Europe 1, 2
- Coxsackie B and other enteroviruses remain important pathogens, particularly in acute and fulminant presentations that can progress to chronic disease 1, 2
- Coinfection with two or more viruses occurs in a substantial minority and may predispose to chronicity 1, 2
Evidence for HSV-Associated Myocarditis
Acute HSV Myocarditis
The European Society of Cardiology lists herpes simplex virus among the various viruses that cause pericarditis and myocarditis 1. Case reports document HSV causing acute myocarditis with multi-organ involvement:
- A 20-year-old woman developed acute myocarditis with cardiogenic shock, diffuse ST-segment elevation, and dilated ventricle with reduced systolic function, confirmed by endomyocardial biopsy showing lymphocytic infiltration and positive HSV antibodies 3
- A 46-year-old woman developed disseminated HSV-1 infection causing hepatitis, encephalitis, and myocarditis after corticosteroid treatment, diagnosed via serum PCR 4
- Fulminant HSV-1 myocarditis in a 3-year-old boy demonstrated CD8+ T-lymphocyte infiltration of the myocardium, suggesting immune-mediated myocardial damage 5
Progression to Chronic Disease
The critical mechanism for chronicity is viral persistence. The American College of Cardiology notes that viral persistence after acute disease can be detected from heart biopsy samples in the setting of chronic dilated cardiomyopathy 1. This sustained viral presence serves as a continuous source of antigen to stimulate immune responses, with deposits of IgM, IgG, and occasionally IgA found in the pericardium and myocardium for years 1.
Pathophysiologic Features of Chronic Myocarditis
When acute HSV myocarditis progresses to chronic disease, the following pathologic changes occur:
- Progressive collagen deposition with mean collagen volume fraction of 14% in chronic myocarditis patients 2
- Late gadolinium enhancement on cardiac MRI in up to 70% of patients with biopsy-proven chronic inflammation and heart failure 1, 2
- Irreversible myocardial fibrosis representing sustained inflammatory damage 2
Clinical Implications and Management Considerations
Diagnostic Approach
For suspected chronic HSV myocarditis, the European Society of Cardiology recommends evaluation of pericardial effusion and/or pericardial/epicardial tissue, preferably by PCR or in-situ hybridization (Level of Evidence B, Class IIa indication) 1. Serum antibody testing showing four-fold rise is suggestive but not diagnostic (Level of Evidence B, Class IIb indication) 1.
Treatment Considerations
A critical pitfall is inappropriate corticosteroid use in viral myocarditis. The American College of Cardiology definitively showed no beneficial effect of prednisone with either azathioprine or cyclosporine in lymphocytic myocarditis, the typical viral pattern 6. Corticosteroids can reactivate viral infections and lead to ongoing inflammation 7.
For confirmed HSV myocarditis, the European Society of Cardiology suggests antiviral treatment under investigation, though evidence remains limited 1, 7. Standard guideline-directed medical therapy for heart failure with reduced ejection fraction is recommended 1, 6.
Special Risk Populations
Immunocompromised patients face higher risk. HHV-6 (a related herpesvirus) caused fatal myocarditis in two immunosuppressed children, suggesting early antiviral treatment could improve outcomes 8. HSV-associated myocarditis has increased incidence in immunocompromised and HIV-infected hosts 1.