Fragmented QRS and other depolarization abnormalities as a predictor of mortality and sudden cardiac death

PURPOSE OF REVIEWSeveral invasive and noninvasive tests for risk stratification of sudden cardiac death (SCD) have been studied. Tests such as microwave T wave alternans (repolarization abnormality) and signal-averaged ECG (depolarization abnormality) have high negative predictive values but low positive predictive values in patients with heart disease. The presence of a fragmented QRS (fQRS) complex on a routine 12-lead ECG is another marker of depolarization abnormality. The purpose of this review is to discuss the potential utility of tests to detect depolarization abnormalities of the heart for the risk stratification of mortality and SCD with main emphasis on fQRS. RECENT FINDINGSfQRS is associated with increased mortality and arrhythmic events in patients with coronary artery disease. fQRS has also been defined as a marker of arrhythmogenic right ventricular cardiomyopathy and Brugada syndrome. In Brugada syndrome, the presence of fQRS predicts episodes of ventricular fibrillation during follow-up. SUMMARYfQRS may be of value in determining the risk for SCD and guiding selection for device therapy in patients with structural heart disease and Brugada syndrome. It is possible that the predictive value of fQRS for SCD can be enhanced further by combining a marker of repolarization abnormality such as microwave T wave alternans.