Role of hepatitis C virus in myocarditis and cardiomyopathies

Recent nationwide clinico-epidemiological surveys in Japan showed that the occurrence of cardiomyopathies was most frequently seen in the age of sixties, and that cardiomyopathies are important causes of heart failure in the elderly. Viral infection was conventionally considered to cause myocarditis, which resulted in the development of dilated cardiomyopathy. Recent studies suggest that hepatitis C virus (HCV) is involved in the development of dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy in addition to myocarditis. Furthermore, left ventricular aneurysm represents the same morbid state not only after myocardial infarction but also after myocarditis. There were wide variations in the frequency of detection of HCV genomes in cardiomyopathy in different regions and in different populations. Major histocompatibility complex class Ⅱ genes may play a role in the susceptibility to HCV infection, and may influence the development of different phenotypes of cardiomyopathy. If in fact the myocardial damage is caused by HCV, it might be expected that interferon (IFN) administration would be useful for its treatment. Hepatitis patients receiving IFN treatment for hepatitis were screened by thallium myocardial scintigraphy, and an abnormality was discovered in half of the patients. Treatment with IFN resulted in a disappearance of the image abnormality. It has thus been suggested that mild myocarditis and myocardial damage may be cured with IFN. We have recently found that high concentrations of circulating cardiac troponin T are a specific marker of cardiac involvement in HCV infection. By measuring cardiac troponin T in patients with HCV infection, the prevalence of cardiac involvement in HCV infection will be clarified. We are proposing a collaborative work on a global network on myocarditis/cardiomyopathies due to HCV infection. (J Geriatr Cardiol 2004;1(2):83-89. )