Disappearance of Q waves following thrombolysis for acute myocardial infarction

The development of Q waves on the surface electrocardiogram generally is considered indicative of myocardial infarction. Such Q waves are usually permanent, though may regress and disappear over months to years. Transient Q waves have been described during myocardial ischemia without evidence of infarction. More recently, Q waves have been noted to develop transiently during the acute phases of infarction, possibly representing stunned myocardium. In this case report, a patient with an evolving anterior myocardial infarction and new septal Q waves was treated with intravenous thrombolytic therapy. Three hours following treatment the patient was clinically improved, and the septal Q waves had been replaced by small but obvious R waves. Despite a large area of myocardium at risk of infarction on the initial electrocardiogram, the resultant infarction was enzymatically and echocardiographically small. Early Q waves in acutely evolving myocardial infarction may represent severely ischemic, rather than irreversibly damaged, myocardium which may still be salvaged with thrombolytic therapy.