Fragmented QRS Complexes Are Associated with Cardiac Fibrosis and Significant Intraventricular Systolic Dyssynchrony in Nonischemic Dilated Cardiomyopathy Patients with a Narrow QRS Interval

Background: Myocardial scar causes heterogeneous ventricular activation, which results in fragmentation of QRS complexes on ECG. Myocardial fibrosis in patients with nonischemic cardiomyopathy (NDCM) can be identified as late gadolinium enhancement (LGE) areas on cardiac magnetic resonance (CMR) studies. We investigated the association of fragmented QRS (fQRS) complexes with systolic dyssynchrony and myocardial fibrosis in patients with NDCM. Methods: Twenty patients with NDCM and sinus rhythm who had fQRS complexes were evaluated with CMR. The association of fQRS complexes with LGE and systolic dyssynchrony was investigated. Results: Nineteen patients had significant systolic dyssynchrony with echocardiography. Among 19 patients with significant dyssynchrony, 14 (74%) patients had fQRS complexes in the most delayed contracting segment or one of the dyssynchronous segments, whereas five patients (26%) had fQRS complexes in a lead which is discordant with the dyssynchronous segment on echocardiography. Seventeen patients had LGE in their CMR. Among the 17 patients with LGE; 13 patients (76%) had fQRS complexes concordant with LGE present segments. Conclusion: Fragmentation of QRS complexes on ECG is associated with intraventricular systolic dyssynchrony and subendocardial fibrosis in NDCM patients with a narrow QRS interval and sinus rhythm. (Echocardiography 2011;28:62-68).