A PROSPECTIVE CASE-CONTROL STUDY OF ANTIBODIES TO COXSACKIE-B VIRUS IN IDIOPATHIC DILATED CARDIOMYOPATHY

Objectives. This study was conducted to determine the frequency and si gnificance of Coxsackie B virus-specific immunoglobulin-M (IgM) in pat ients with idiopathic dilated cardiomyopathy and compare them with the frequency in both unmatched and matched control subjects. Background. The principal evidence supporting a pathoetiologic role for Coxsackie B viruses in human dilated cardiomyopathy is derived from retrospecti ve serologic studies. These studies have evaluated patients with end s tage disease and have failed to recognize the importance of assessing both matched and unmatched control subjects. Methods. In this prospect ive case control study, we assessed sera for Coxsackie B virus specifi c IgM (serotypes B1 to B5) from 114 patients with dilated cardiomyopat hy at diagnosis or referral to our center, 94 healthy unmatched contro l subjects, 41 healthy matched control subjects from the same general practitioner and 32 members of the patients' own households. Results. A higher frequency of positive Coxsackie B virus IgM was observed in p atients with dilated cardiomyopathy than in unmatched control subjects (33% vs. 5%; p = 3 x 10(-7)). In patients with dilated cardiomyopathy , the response was monotypic (84%), commonly against serotypes B2 and B5, and was not associated with any clinical or histologic feature. Th e frequency of positive virus specific IgM was similar in patients wit h dilated cardiomyopathy and their 41 matched community control subjec ts (46% vs. 27%; p = 0.11) and 32 household contacts (37% vs. 28%; p = 0.59). Control subjects who tested positive for virus specific IgM te nded more commonly to be seropositive than did control seronegative su bjects (community control subjects 37% vs. 18%, p = 0.32; household co ntacts 42% vs. 20%; p = 0.36) and had an identical serotypic response in 4 (33%) of 12 cases. Conclusions. The frequency of Coxsackie B viru s IgM was higher in patients with dilated cardiomyopathy than in unmat ched control subjects but was similar in patients and control subjects who shared the same environment, indicating local spread of infection . The reason for the association between Coxsackie B virus IgM and dil ated cardiomyopathy and its relevance to pathogenesis remain to be est ablished.