Possible pitfalls in the diagnosis of acute myocardial infarction in acutely psychotic patients.

: The disturbed communication of the acutely psychotic patient with Emergency Room (ER) personnel can occasionally lead to a missed or delayed diagnosis of acute myocardial infarction. Conversely, miscommunication may also lead to a false positive diagnosis of acute myocardial ischemia or infarction. We describe a patient who failed to report lithium ingestion because of his psychotic and toxic state. Moreover, the patient was agitated and was treated with intramuscular haloperidol. These factors produced electrocardiographic changes due to the lithium and a rise in serum creatine kinase due to the intramuscular haloperidol, two criteria which could mislead an inexperienced observer to make the false diagnosis of acute myocardial ischemia or infarction. Lithium related electrocardiographic abnormalities and the causes for elevated creatine kinase isoenzymes are reviewed.