Natural history of congenital complete atrioventricular block.

An update of studies on the natural history of congenital complete AV block is presented. A risk for heart failure, syncope, and sudden death is present at any age including fetal life. Unfavorable prognostic signs in utero are low and decreasing ventricular rate (VR), hydrops, AV valve regurgitation, and low aortic flow velocity. Indications for pacing in infancy are congestive heart failure, ventricular rate < 55 beats/min in isolated block and < 65 beats/min with associated disease, prolonged OTc, syncope attacks, frequent ventricular ectopic beats, and alternating ventricular pacemakers. Indications for immediate pacing in childhood and adult life are syncope, presyncope, VR rates lower than median for age, periods of junctional exit block, prolongation of QTc and mitral regurgitation, and change of ventricular pacemaker. Pacing is recommended to all patients older than 15 years.