Virological study of idiopathic cardiomyopathy: serological study of virus antibodies and immunofluorescent study of myocardial biopsies.

In 113 patients with idiopathic cardiomyopathy paired sera obtained 2--4 weeks apart were examined for neutralizing antibody to coxsackie B 1--6, and echo 4, 6, 7, 9 and 11 viruses. Only eight cases (6.9 per cent) showed a significant change in titer, indicating a virus infection during or shortly before the study. Complement-fixing antibody titers were measured in 126 patients and neutralizing antibodies in 116 patients with idiopathic cardiomyopathy. More patients had complement-fixing antibody titers greater than or equal to 1 : 4 to coxsackie B and herpes simplex virus than did controls (p less than 0.05). Neutralizing antibody titers to coxsackie B 1 and B 3 virus were also higher in patients (p less than 0.01 for titers greater than or equal to 1 : 4 and p less than 0.05 for titers greater than or equal to 1 : 16). Complement-fixing antibody titers greater than or equal to 1 : 4 to herpes simplex virus were more frequent (p less than 0.05) in hypertrophic cardiomyopathy and those to coxsackie B, herpes simplex and influenza A virus were more frequent in congestive cardiomyopathy. Neutralizing antibody titers were more common to coxsackie B 3 (p less than 0.05 for titers of greater than or equal to 1:4) in hypertrophic cardiomyopathy, while in congestive cardiomyopathy they were more common to B 1 (p less than 0.01 for titers greater than or equal to 1 : 4 and p less than 0.05 for titers greater than or equal to 1 : 16), to coxsackie B 3 virus (p less than 0.001 for titers greater than or equal to 1 : 4 and p less than 0.04 for titers greater than or equal to 1 : 16) and to coxsackie B 5 (p less than 0.05 for titers greater than or equal to 1 : 4 or more) and to echo 6 virus (p less than 0.05 for titers greater than or equal to 1 : 4 and greater than or equal to 1 : 128). Immunofluorescent study of 61 cases showed no virus antigens in the biopsied myocardium even in patients who had significant changes in neutralizing antibody titers in paired sera. These results suggest a relationship between virus infection and idiopathic cardiomyopathy not only of the congestive type but also of the hypertrophic type. However, they do not provide definite proof of the virus infection theory of the disease.