Fragmented QRS: A simple electrocardiographic prognostic marker in cardiovascular disease

Fragmented QRS is defined as the presence of R′ wave or notching of R or S wave in the presence of narrow QRS. It indicates heterogeneous depolarization of the ventricular myocardium that can occur due to ischemia, fibrosis, or scar. It may also be a marker of coronary microvascular dysfunction. In the context of epicardial coronary artery disease, it is associated with multivessel disease and greater incidence of cardiac events. It has been shown to be an indicator of higher incidence of arrhythmias and sudden death in arrhythmic right ventricular dysplasia, Brugada syndrome, and acquired long QT syndrome. Its regression following cardiac resynchronization therapy suggests electrical reverse remodeling. It has also been shown to be a marker of myocardial involvement in congenital heart diseases and is helpful in diagnosing subclinical cardiac involvement in various systemic diseases.