Abstract
This communication is a report on the clinicopathologic study that was conducted to clarify the characteristics of left axis deviation seen in elderly people. This series dealed with 1, 000 cases of consecutive autopsies performed on elderly patients. In this study -30°or greater angles of the mean frontal plane electric axis were classified under left axis deviation. According to this criterion left axis deviation was found in 147 cases (14.7%), and 189 controls (normal axis+left axis quasi-deviation) were chosen at random among the remaining 853. The incidence of left axis deviation was age-related in the patients of either sex over 80 years. The main complications consisted of myocardial infarction in 17.0%, bundle branch block in 13.0%, and both in 4.0%. Isolated LAD that supervenes on heart disease other than myocar-dial infarction or bundle branch block was present in 30.6%. Left ventricular hypertrophy, hypertrophy of the heart and coronary sclerosis were more advanced in patients with myocardial infarction than in controls, while there was no difference between patients with other complication and controls. Histologically, the involvement of the septum was the characteristic finding of myocardial infarction or myocardial infarction with bundle branch block that complicated in the cases with left axis deviation and the finding was noted in 43.8 and 50.0% respectively. When the frontal plane initial and terminal vectors (0.04 second) were compared in cases of left axis deviation, it was found that the terminal vector had a greater effect on the determination of the frontal plane mean electric axis than the initial one regardless of the presence of myocardial infarction. Myocardial necrosis as in myocardial infarction provides a partial explannation of the etiology of left axis deviation, but our experience suggests that cases of left axis deviation for the most part have nothing to do with hypertrophy of the heart or coronary sclerosis and that it is ascribable to conduction defects and myocardial fibrosis as bundle branch block is.
