Infranodal conduction time ≥70 msec in chronic bundle branch block predicted higher rates of 2nd or 3rd degree AV block (21% vs 1.3%) and severe heart failure (38% vs 16%) than <70 msec.
Does prolonged infranodal conduction time (H-Q ≥ 70 msec) predict progression to advanced AV block, severe heart failure, or sudden death in patients with chronic bundle branch block?
Prolonged infranodal conduction time (H-Q ≥ 70 msec) identifies patients with chronic bundle branch block at high risk for progression to advanced AV block and severe heart failure.
Absolute Event Rate: 0% vs 0%
His bundle recordings were obtained in 121 patients with chronic bundle branch block and the patients were followed for a mean period of 18 months. Seventy-nine patients had an infranodal conduction time (H-Q) less than 70 msec while 42 had H-Q greater than or equal to 70 msec. There was no significant difference in mean age, smoking history, diabetes, syncope, dizziness, blood pressure, and serum cholesterol or triglyceride levels between the two groups. There was a significantly greater incidence of progresssion to second degree or third degree atrioventricular block (9/42, 21%), and of severe congestive heart failure (16/42, 38%) in patients with H-Q greater than or equal to 70 compared with those with H-Q less than 70 (1/79, 1.3%; and 13/79, 16%, respectively). The risk of sudden death was significantly greater only in the group with H-Q greater than or equal to 70 and severe congestive heart failure. There was no correlation between the presence of first degree atrioventricular block and/or any particular type of bundle branch block pattern with sudden death and/or progression to second degree or third degree atrioventricular block. Analysis of the surface electrocardiogram is only of limited value in predicting high risk patients with chronic bundle branch block. Electrophysiologic studies are of greatest value in patients with bundle branch block with transient neurologic symptoms in whom no cause for the symptoms is evident.
Scheinman et al. (Mon,) reported a other. Infranodal conduction time ≥70 msec in chronic bundle branch block predicted higher rates of 2nd or 3rd degree AV block (21% vs 1.3%) and severe heart failure (38% vs 16%) than <70 msec.