Hemiblock in acute myocardial infarction.

The incidence of the left bundle-branch hemiblocks in a series of 250 consecutive acute myocardial infarctions is reported and correlated with the site of the infarction. Hemiblock was found in 40 patients (16 percent)—left anterior hemiblock in 38, left posterior hemiblock in only two. Left anterior hemiblock is apparently the most common intraventricular conduction disturbance encountered in acute myocardial infarction.