A female is on prophylactic penicillin therapy for rheumatic hea disease. She often gets attacks of rheumatic fever in the past. Which valve is least involved in chronic rheumatic fever?

Chronic rheumatic hea disease results from single or repeated attacks of rheumatic fever that produce rigidity and deformity of valve cusps, fusion of the commissures, or shoening and fusion of the chordae tendineae. The mitral valve alone is affected in 50-60% of cases; combined lesions of the aoic and mitral valves occur in 20%; pure aoic lesions are less common. Tricuspid involvement occurs in about 10% of cases but only in association with mitral or aoic disease and is thought to be more common when recurrent infections have occurred. The pulmonary valve is rarely affected long term. Ref: Bashore T.M., Granger C.B., Hranitzky P., Patel M.R. (2013). Chapter 10. Hea Disease. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds), CURRENT Medical Diagnosis & Treatment 2013.