QRS duration and morphology, evaluated via a standard 12-lead electrocardiogram (ECG),
represent an opportunity to derive useful prognostic information regarding the risk of subsequent
cardiac events or therapeutic outcomes. Prolonged QRS duration, and the presence of
intraventricular conduction abnormalities, usually indicate the presence of changes in the
myocardium due to underlying heart disease.
Prolonged QRS duration is often associated with depressed ejection fraction or enlarged left
ventricular volumes, but several studies have demonstrated that this simple ECG measure
provides independent prognostic value, after adjusting for relevant clinical covariates.
Post-infarction patients with prolonged QRS duration have a significantly increased risk of
mortality, although data associating QRS prolongation specifically with sudden death is less
supportive. In non-ischemic cardiomyopathy, there is no evidence that QRS duration has
prognostic significance in predicting mortality or sudden death. Prolonged QRS duration, and
especially presence of left bundle branch block, seems to predict a benefit from cardiac
resynchronization therapy in both ischemic and non-ischemic cardiomyopathy patients.
Therefore, QRS duration and morphology should not only be considered a predictor of death or
sudden death in patients after myocardial infarction, and in those suspected of coronary artery
disease, but also as a predictor of benefit from cardiac resynchronization therapy in patients
with heart failure, whether of an ischemic or non-ischemic origin. (Cardiol J 2011; 18, 1: 8-17
