Left bundle branch block and right axis deviation: a report of 36 cases.

Right axis deviation (RAD) with left bundle branch block (LBBB) is a rare combination. From a database of 636,000 electrocardiograms we report a series of 36 patients with this disorder. The majority of subjects had dilated cardiomyopathy with biventricular enlargement. LBBB was fixed in 21 of 36 cases. It was freshly acquired, episodic, intermittent, or physiologic in 15 of 36. The RAD was episodic in 30 of 36; it was fixed and concurrent with LBBB in only 2 cases, and never episodically concurrent. Reported for the first time here were 4 of 36 cases in which the combination of LBBB and RAD was elicited with atrial premature impulses as a rare form of QRS aberration. In one case where the combination was intermittent, a clear relationship with freshly acquired intermittent posterior fascicular block was demonstrated. The possible relationship of the deviation with variable degrees of right ventricular overload is discussed.