Complete left bundle branch block with marked left axis deviation of qrs clinical and anatomical study.

In a series of 840 cases of unselected complete LBBB, 2 groups were compared with each other, one of 174 cases of complete LBBB with a QRS axis markedly deviated leftward, from minus50 to minus 90 degree (group A), the other 434 complete LBBB with a normal QRS axis included between minus20 and plus30 degree (group B). Group A differed from group B by the etiological predominance of primary cardiomyopathies, the lesser frequency of hypertensive and/or coronary heart disease, the rarity of idiopathic complete LBBB. It was commonly combined with marked enlargement of the X-ray heart shadow, with marked widening of QRS complex and had a definitely more severe prognosis. The anatomical study performed in 88 cases (52 group A, 36 group B) showed on thw whole a slightly more enlarged heart and a more marked left ventricular dilatation in group A. There were no differences in the state of the coronary arteries and in the frequency of myocardial infarction. Microscopical examination of the left bundle branch, performed in 42 cases (25 group A, 17 group B), showed the habitual and intense changes of the bundle branch, but without obvious difference between the 2 groups concerning the topographical distribution of the lesions.