RELATIONSHIP BETWEEN MYOCARDIAL FIBROSIS AND EPICARDIAL AND SURFACE ELECTROCARDIOGRAM Q-WAVES IN MAN

The extent of transmural loss of myocardium in man which results in both the development and duration of Q waves on local electrocardiograms (ECGs) and the surface ECG is incompletely understood. Accordingly, at the time of open heart surgery, epicardial electrograms and transmural biopsies from the same site were obtained in 18 patients (19 sites). Of nine areas with epicardial R waves, eight were histologically normal while one had only <10% epicardial muscle loss. Initial Q waves were recorded from the epicardial electrogram in ten areas. Of six areas with epicardial Q waves ≥.04 second, four had 75-100% fibrosis associated with a QS pattern. Two of the six had 50-74% fibrosis distributed transmurally which were associated with a qR pattern with initial Q waves of 0.04 second and 0.05 second respectively. Of the remaining four zones and epicardial qR complexes with Q waves of .03 second in duration, two showed 35% muscle loss in the endocardial half and one exhibited 35% loss distributed transmurally, while one had a normal biopsy. Biopsies obtained from twelve areas were reflected by a normal QRS on the corresponding leads of the surface ECG. Eight biopsies were normal while three demonstrated less than 50% involvement. Only one had more than 50% transmural muscle loss in the zone corresponding to the ECG localization. Of seven biopsies obtained from areas with associated pathologic surface ECG Q waves, five had greater than 50% transmural loss. Thus, a quantitative relationship appears to exist between the amount and location of myocardial fibrosis and both the presence and duration of Q waves on epicardial electrograms. This relationship also appears to hold to a somewhat lesser degree with Q waves exhibited on the surface ECG. © 1978 Research in Electrocardiology, Inc.