A 4-year-old girl with giant left atrial diverticulum resulting in severe mitral regurgitation.

Left atrial diverticulum is rare in a pediatric patient. A 4-year-old girl underwent a left atrial plication concomitant with mitral valve replacement, and early postoperative course was uneventful. This patient has remained asymptomatic with no evidence of recurrent diverticular formation after 9 months of follow-up.