[Upgrading to biventricular pacing for dilated cardiomyopathy following right ventricular pacing in a young patient].

A 2-day-old male infant required a conventional VVI pacemaker for congenital atrioventricular block. Three years later, he developed progressive heart failure due to left ventricular (LV) dysfunction and mitral regurgitation despite optimized medical treatment, and a cardiac resynchronization therapy (CRT) device was implanted. This is the first Portuguese report of CRT in a pediatric patient. One-year echocardiographic follow-up showed that LV shortening fraction had improved and LV end-diastolic dimension and mitral regurgitation had decreased. New York Heart Association class had improved from III-IV to I at 1-year follow-up.