Mean electrical QRS axis on the frontal plane in electrocardiograms of middle-aged and elderly hospital patients.

The mean electrical QRS axis (AQRS) on the frontal plane was determined on electrocardiograms recorded shortly before death in 1249 patients. Cardiopulmonary diseases were sought at autopsy. Cases with CRBBE, CLBBB, WPW or idioventricular rhythm were excluded. In 171 patients without cardiopulmonary diseases, the AQRS tended to deviate to the left with age. In patients aged 30--49 the median AQRS was +55 degrees ranging between -30 degrees--90. In 99% of older patients, it stayed between -45 degrees--75 degrees. No sex difference was found. A large AQRS deviation was characteristic of patients with cardiopulmonary diseases. In one third of male pulmonary patients aged 50 or over, the AQRS pointed outside -45 degrees or +75 degrees. Rightward deviation of +90 degrees was found in 20% of younger patients. In patients aged 50 or over with myocardial infarction, rightward AQRS deviation of +75 degrees was observed in 11%, and below -45 degrees in 8% of the patients. Abnormal deviation was most common in association with inferoposterior or lateral wall infarctions. Abnormal deviation of the frontal plane QRS axis seems to coincide only with cardiac or pulmonary diseases. Extreme rightward deviation suggests a condition of right ventricular overload, but leftward deviation occurs in patients with pulmonary and with left ventricular diseases.