[Infranodal chronic auriculo-ventricular block in subjects under 50 years of age].

The aetiology and evolution of chronic infranodal atrioventricular block (AVB) of young patients are not well known: are they the first sign of subclinical myocardial disease which can only be diagnosed by long term follow-up or do they represent isolated degenerative disease of the conduction tissue (Lenegre's disease)? Eighteen patients (15 men, 3 women) aged 25 to 49 years (average 41.5 years) were followed up for periods of 2 to 20 years (average 7.33 years) after pacemaker implantation for syncopal AVB. Follow-up was focused on the evolution of the conduction defects and the cardiovascular status. The patients were divided into two groups at the initial assessment: Group I: 15 patients with documented AVB; Group II: 3 patients in whom all basal recordings showed sinus rhythm (SR). Apart from one patient with an early non-ischaemic dilated cardiomyopathy, there was no previous cardiovascular disease. There was no history of ischaemic heart disease, drug effects, infection or inflammation in favour of an acute AVB. Three patients had permanent AVB, either 2nd degree with bundle branch block (N = 2) or 3rd degree block (N = 1). The other 15 patients were in sinus rhythm with bundle branch block: left bundle branch block (LBBB) in 5 cases, right bundle branch block (RBBB) in 3 cases; RBBB with left anterior hemiblock in 5 cases, RBBB and left posterior hemiblock in 2 cases. Paroxysmal AVB was recorded in 12 of these 15 patients on at least one occasion.(ABSTRACT TRUNCATED AT 250 WORDS)