[Prognosis of isolated atrioventricular block in children. Single center study of 135 cases].

Abstract

Isolated complete atrio-ventricular (AV) block in children occurs in anatomically normal hearts in the absence of any known predisposing factor likely to have caused the block. This study aimed to define the current prognosis of these conduction disorders.
135 patients with isolated complete AV block, diagnosed before the age of 15 years, were included in this monocentric, retrospective study.
52.6% of the cases were diagnosed in the antenatal or neonatal period, demonstrating their congenital nature. The disease was heralded by symptoms in only 6.7% of cases. A search for maternal anti-Ro/La antibodies was performed in 111 of the patients. It was positive in 56 cases, and was associated with an early diagnosis, a short delay in cardiac pacemaker implantation, and the occurrence of cardiomyopathy (16 cases), the latter representing a critical point in the progression of the disease (37.5% mortality at 6 years). Among the 55 cases not associated with antibodies, 2 cases were familial and no etiology was discovered in the others. The diagnosis was therefore made later, and no progression to cardiomyopathy was noted. A cardiac pacemaker was implanted in 122 patients (66 epicardial, 56 endocardial).
Isolated complete AV block in children is not a homogenous entity: 'immunological' blocks are genuinely congenital and their prognosis remains grave, owing to the risk of cardiomyopathy, which is sometimes diagnosed late. The other types of block are diagnosed much later in childhood, and their mechanism is still unknown. They have a good prognosis as long as the indications for pacing the child are respected.