Abstract
BACKGROUND: Right bundle branch block (RBBB) is not commonly associated with structural heart
disease and left ventricular (LV) systolic dysfunction. The purpose of the present
study was to determine whether the QRS duration and degree of right axis deviation
(RAD) or left axis deviation (LAD) in patients with RBBB predicted a subset of patients
with significant LV systolic dysfunction.
METHODS: In the present prospective study, 75 of 200 consecutive patients with RBBB had their
ejection fraction (EF) evaluated by echocardiography. The relationship among QRS duration,
axis and EF was derived.
RESULTS: There were no significant differences in sex and EF among the patients with a normal
axis, RAD or LAD. The EFs of patients with a normal axis (n=27), RAD (n=15) and LAD
(n=33) were 52±15%, 49±14% and 46±17%, respectively (P=0.35). The mean EF (46±16%)
of patients with a QRS duration of 150 ms or greater (n=53) was not significantly
different from the mean EF (49±18%) of patients with a QRS duration of less than 150
ms (n=22) (P=0.54). For patients with a QRS of 120 ms or greater and less than 150
ms (n=22), QRS of 150 ms or greater and 180 ms or less (n=48), and QRS of greater
than 180 ms (n=5), the mean EFs were 49±18%, 47±16% and 44±7%, respectively (P=0.78).
There was no significant correlation between QRS duration and EF in all patients (r=0.03,
P=0.83), EF and RAD (r=0.38, P=0.16), or EF and LAD (r=0.26, P=0.14).
CONCLUSIONS: In patients with RBBB, the QRS duration and axis do not have a significant relationship
with EF. Furthermore, prolongation of the QRS duration (150 ms or greater) in the
presence of RBBB is not a marker of significant LV systolic dysfunction.
