The Clinical Value of Vectorcardiography in Old Myocardial Infarction With Particular Emphasis on Its Usefulness in Cases Without Significant Q Waves

Serial observations on the electrocardiograms in 278 cases of definite acute myocardial infarction revealed the disappearance of diagnostic Q waves in 34 (12.2%) of them during a mean follow-up of 12.1 months. A vectorcardiographic diagnosis of old myocardial infarction was possible in 14 of these 34 cases without Q waves on the basis of abnormal distortion and/or indentation of the QRS loop. The cases with old myocardial infarction were divided into three groups, namely those without abnormal Q waves and without any obvious evidence of myocardial infarction in vectorcardiography (group I), those without abnormal Q waves but with diagnostic vectorcardiographic abnormalities (group II) and those with persistent abnormal Q waves (group III). The severity of coronary atherosclerosis did not differ among the three groups. On the other hand, the involvement of myocardial contraction was the least extensive in group I, more extensive in group II and the most extensive in group III. Thus, vectorcardiography was more sensitive in the diagnosis of old myocardial infarction than routine 12-lead electrocardiogram. The present results also indicate that serial observations on electrocardiograms are of considerable value in myocardial infarction for assessment of the extent of myocardial lesions.