[Development at 5 years of chronic branchial blocks in 164 patients fitted with pacemakers without documented spontaneous atrioventricular block. Study of predictive criteria].

When no complete atrioventricular block (CAVB), paroxysmal and spontaneous, is recorded, implanting a pacemaker in patients with chronic bundle branch block (CBB) has an arbitrary aspect which must be reduced as much as possible. In order to determine more precisely the criteria predicting an evolution towards CAVB, we studied the electrocardiographic changes observed in 164 patients with various types of CBB. 110 patients had a right bundle branch block which was isolated (RBB) in 16 cases, associated with a left anterior hemiblock (RBB + LAH) in 74 cases and associated with a left posterior hemiblock (RBB + LPH) in 20 cases; 54 patients had a left bundle branch block with a normal axis in 26 cases (LBB - NA) and with a strongly left axis in 28 cases (LBB - LA). All patients had been fitted with a pacemaker. Patients were followed up for a mean period of 5 years (59.1 +/- 25.3 months), the minimum being 2 years. 49.4 p. 100 of them had experienced one ore serveral syncopes. The basal HV interval, studied in 90.2 p. 100 of the patients, was 60 ms or more in 64.9 p. 100 of those who were explored. An ajmaline test, performed in 60 of the 85 patients whose basal HV was less than 70 ms, demonstrated at least a 100 ms or more prolongation of HV in 41 cases (68.3 p. 100).(ABSTRACT TRUNCATED AT 250 WORDS)