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)     

Cardiac Resynchronization Therapy in Patients With Heart Failure and Narrow QRS Complexes

Background

Cross correlation analysis (CCA) using tissue Doppler imaging has been shown to be associated with outcome after cardiac resynchronization therapy (CRT) in patients with heart failure (HF) with wide QRS. However, its significance in patients with narrow QRS treated with CRT is unknown.

Dyssynchrony and Response to Cardiac Resynchronization Therapy in Heart Failure Patients With Unfavorable Electrical Characteristics

BackgroundAmong heart failure (HF) patients undergoing cardiac resynchronization therapy (CRT), those with unfavorable electrical characteristics (UEC) are less frequently CRT responders.ObjectivesIn this study, the authors sought to evaluate the relationship between preprocedural echocardiographic parameters of electromechanical dyssynchrony (EMD) and outcome following CRT.MethodsAmong 551 patients receiving CRT, 121 with UEC, defined as atypical left bundle branch, presence of right bundle branch block, or unspecified intraventricular conduction disturbance, were enrolled. Indices of EMD were presence of septal flash, apical rocking, septal deformation patterns, and global wasted work (GWW), determined with the use of speckle-tracking strain echocardiography. Endpoints were response to CRT, defined as a relative decrease in left ventricular end-systolic volume ≥15% at 9-month postoperative follow-up, and all-cause death or HF hospitalization during follow-up.ResultsAmong the 121 patients, 68 (56%) were CRT responders. In multivariate analysis, GWW ≥200 mm Hg% (adjusted odds ratio [aOR]: 4.17 [95% CI: 1.33-14.56]; P = 0.0182) and longitudinal strain septal contraction patterns 1 and 2 (aOR: 10.05 [95% CI: 2.82-43.97]; P < 0.001) were associated with CRT response. During a 46-month follow-up (IQR: 42-55 months), survival free from death or HF hospitalization increased with the number of positive criteria (87% for 2, 59% for 1, and 27% for 0). After adjustment for established predictors of outcome in patients receiving CRT, absence of either of the 2 criteria remained associated with a considerable increased risk of death and/or HF hospitalization (adjusted HR: 4.83 [95% CI: 1.84-12.68]; P = 0.001).ConclusionsIn patients with UEC, echocardiographic assessment of EMD may help to select patients who will derive benefit from CRT. (Echocardiography in Cardiac Resynchronization Therapy [Echo-CRT]; NCT02986633)