Myocardial disease in Rocky Mountain spotted fever: clinical, functional, and pathologic findings.

Rocky Mountain spotted fever is an acute febrile illness with a significant mortality rate. Cardiac involvement has been sporadically reported, but is more common than appreciated from pathologic studies. The lesion is one of vasculitis, with secondary thrombosis and tissue necrosis. Cardiac function abnormalities may be detected by echocardiography and may persist after resolution of other manifestations of disease. Myocardial involvement is frequently present in Rocky Mountain spotted fever; close monitoring and an aggressive therapeutic approach are essential if the high case fatality rate (7%-11%) is to be reduced. Pathophysiologic consequences of damage to other organ systems may affect circulatory function and should be carefully evaluated.