Left ventricular hypertrophy in presence of complete left bundle-branch block.

Electrocardiograms of 2500 consecutive patients who died in hospital were reviewed in order to study the relation ofcomplete left bundle-branch block to pathological determinants ofanatomical left ventricular hypertrophy. Of these, 43 patients demonstrated complete left bundle-branch block and all but two had anatomical left ventricular hypertrophy at necropsy. -Mean values of total heart weight and percentage total heart weight of normal were significantly higher in this group of 43 patients with complete left bundle-branch block than in a control necropsy group of 300 patients with anatomical left ventricular hypertrophy but without complete left bundle-branch block. Left ventricular wall thickness did not correlate with other measures of left ventricular muscle mass. Commonly used electrocardiographic voltage criteria for left ventricular hypertrophy identified approximately one-half of the 41 patients with left bundle-branch block and anatomical left ventricular hypertrophy. The degree of electrocardiographic voltage abnormality correlated modestly with total heart weight and percentage total heart weight of normal. A group of25 patients was studied in whom electrocardiograms were available before and after complete left bundle-branch block. Normal voltage before left bundlebranch block tended to remain normal, while abnormally high voltage tended to fall after complete left bundle-branch block developed. Complete left bundle-branch block in a necropsy population characterised a group with extreme anatomical left ventricular hypertrophy. The sensitivity of the usual electrocardiographic left ventricular hypertrophy voltage criteria in the presence of complete left bundlebranch block is only slightly less than in patients with left ventricular hypertrophy alone. The degree of electrocardiographic voltage abnormality with complete left bundle-branch block shows modest correlation with degree of anatomical left ventricular hypertrophy.