The role of fragmented QRS complexes in cardiovascular diseases: Pathophysiology, prognosis, and clinical applications

Fragmented QRS (fQRS) is an electrocardiographic marker that reflects conduction abnormalities caused by myocardial scarring, fibrosis, or structural remodeling. Over the past two decades, fQRS has gained increasing attention for its diagnostic and prognostic implications in cardiovascular diseases (CVDs). In ischemic heart disease, fQRS is strongly associated with myocardial infarction, scar burden, and adverse cardiac outcomes, including ventricular arrhythmias and sudden cardiac death. Beyond coronary artery disease, fQRS has also been linked to poor prognosis in non-ischemic cardiomyopathies and heart failure, where it correlates with impaired ventricular function, arrhythmic events, and limited response to cardiac resynchronization therapy. Moreover, fQRS is observed in arrhythmogenic conditions such as Brugada syndrome and in structural disorders including congenital heart disease, myocarditis, and infiltrative cardiomyopathies, serving as a marker of myocardial fibrosis and a predictor of arrhythmogenic risk. The clinical utility of fQRS lies in its simplicity, availability, and low cost, as standard 12-lead electrocardiography is universally accessible. Its incremental prognostic value beyond conventional parameters such as left ventricular ejection fraction highlights its potential to refine risk stratification and guide therapeutic strategies, particularly in identifying candidates for implantable cardioverter-defibrillators. However, widespread clinical adoption is limited by inconsistent definitions, lack of standardization, and variability in interpretation. Future directions include large-scale validation studies, integration with multimodality risk assessment, and the application of artificial intelligence to improve automated detection and predictive accuracy. Overall, fQRS represents a promising, non-invasive tool that could enhance the management of patients across the spectrum of CVDs.