[Transient abnormal Q waves under acute myocardial infarction in patients with pneumoconiosis]

Abnormal Q waves have been generally considered to be one of the most reliable indicators of permanent myocardial cell death, namely myocardial infarction. Pathological and experimental studies also support this concept. However, some cases of abnormal Q waves disappearing after myocardial infarction have been reported. Recently, we observed acute myocardial infarction with pneumoconiosis. In this case, a patient with abnormal Q waves appeared within 24 hours after the onset of acute myocardial infarction. But, thirteen days later, these abnormal Q waves disappeared on the surface twelve-lead ECG. The precise mechanism for regression or disappearance of abnormal Q waves is not yet well known. Several studies pointed out a relation of this phenomenon to myocardial collateral circulation under ischemia. And, Nonkin et al reported that, patients with chronic lung disease such like pneumoconiosis, had high incidence of collateral circulation to the myocardium. This was due to chronic hypoxic conditions. In our case, cineangiographic study could not be performed, but disappearance of abnormal Q wave (so called Transient abnormal Q waves), following acute myocardial infarction may be related to the presence of chronic lung disease.