M-mode echocardiographic abnormalities in Rocky Mountain spotted fever.

Rocky Mountain spotted fever is a serious acute systemic illness frequently complicated by cardiac involvement. To evaluate the spectrum of myocardial dysfunction, we obtained M-mode echocardiograms on nine consecutive patients with Rocky Mountain spotted fever within 72 hours of admission. Seven of the nine patients had echocardiographic evidence of impaired left ventricular function; two of the seven had no other evidence of cardiac involvement. The extent of impairment of left ventricular function reflected the clinical severity of the illness. Left ventricular myocardial dysfunction is a frequent complication of Rocky Mountain spotted fever. Echocardiography may provide the only clinical evidence of cardiac involvement in these patients.