ECG diagnostic pearls and pitfalls. 1. Acute myocardial infarction and pseudoinfarction.

An accumulation of valuable empirical data supports the clinical usefulness of the ECG in diagnosis of cardiac disorders and electrolyte disturbances. Although the patterns in some conditions are sufficiently characteristic to be diagnostic, many ECG abnormalities fit several conditions and many mimic the findings in myocardial infarction. Thus, interpretation presents many pitfalls, and each ECG must be carefully scrutinized in light of the complete clinical picture and laboratory data. ECGs may be used to diagnose, date, and locate the site of myocardial ischemia or infarction and many afford clues to pseudoinfarction patterns as described here. The ECG is also valuable in assessment of fascicle block and ventricular hypertrophy (part 2, page 136) and in diagnosis of drug-induced and electrolyte disturbances (part 3, page 145).