Clinical significance of terminal QRS abnormalities in the setting of inferior myocardial infarction

To ascertain the clinical relevance of terminal electrocardiographic (ECG) QRS prolongation in the setting of inferior myocardial infarction, 32 patients were studied by radionuclide ventriculography to evaluate regional left ventricular contractility. Of the 32 patients, 16 had evidence of terminal QRS prolongation and notching associated with inferior myocardial infarction, and 16 had isolated ECG evidence of inferior myocardial infarction without terminal QRS prolongation. The regional ejection fraction in the posterolateral and inferoapical regions of patients with terminal conduction delay was lower than those without this conduction delay. This group also demonstrated a lower global ejection fraction than those patients with ECG evidence of inferior myocardial infarction without terminal QRS changes. Terminal QRS abnormalities are important qualitative predictors of left ventricular dysfunction in the setting of inferior myocardial infarction.