Toxoplasmic infection in cardiac disease.

In 18 patients who presented in less than 2 years with heart disease characterized by arrhythmias (including atrial fibrillation, ventricular arrhythmias and heart block), atypical chest pain, pericarditis and cardiac failure, extensive investigation revealed no cause for the disease except for evidence of toxoplasmic infection. One patient had acute toxoplasmosis; the other 17 patients had chronically increased titers, higher than the expected level in the community and also higher than in a control series of patients with well defined heart disease. Toxoplasmosis is probably a fairly common cause of heart disease in this community. The source of infection appeared to be cats, uncooked meat and congenital infection. Patients received chemotherapy with either pyrimethamine and sulfadiazine or tetracycline. Serious relapse occurrred in three patients and embolic complications in two. Experimental myocarditis occurs when toxoplasmic cysts rupture within the heart; therefore clinical symptoms may occur sporadically during a chronic infection.