Clinical significance of abnormal Q wave disappearance in acute transmural myocardial infarction.

The clinical features of acute myocardial infarction patients in whom abnormal Q wave disappeared were analyzed. Of 201 patients, 40 (20%) (Group A) showed disappearance of Q wave in serial electrocardiograms. Regional ejection fraction of the infarcted portion improved significantly (from 24 +/- 2 to 34 +/- 4%, p less than 0.001) during chronic phase in Group A, but no such improvement was present in Group B patients who showed no change in the Q wave. Global ejection fraction was greater and percent akinetic segment was smaller in Group A than in Group B at chronic phase. Coronary occlusion occurred more often at segment 7 in Group A; in Group B, occlusion occurred more frequently upstream at segment 6, suggesting Group A had a smaller area of risk. Spontaneous recanalization was more often (57%) and complete occlusion was less frequent in Group A. These indicate that Group A is characterized by a smaller area of risk, smaller infarct size, earlier reperfusion, and greater improvement in wall motion. Twenty-eight patients (70%) of Group A lost Q wave within one month and 12 patients (30%), after 3 months or more. Electrical stunning of the myocardium may be a possible mechanism for the early disappearance of Q waves, and anatomical healing for the late disappearance of Q waves.