Changes in left ventricular synchrony and systolic function in dilated cardiomyopathy patients with fragmented QRS complexes

AIMS: Fragmented QRS (f-QRS) complexes are associated with adverse cardiovascular events in patients with coronary heart disease; however, the effects on patients with dilated cardiomyopathy (DCM) remain elusive. This study is to investigate the changes of left ventricular (LV) synchrony and systolic function in DCM patients with f-QRS complexes. METHODS AND RESULTS: Twenty DCM patients with f-QRS complexes and 29 DCM patients without f-QRS (n-QRS) complexes were enrolled. The LV segmental longitudinal, radial and circumferential time to peak strain and general longitudinal systolic strain, radial strain, circumferential strain were measured, respectively, by speckle tracking imaging. The LV segmental standard deviations and maximal differences were also calculated. The LV dyssynchrony was defined as the time in peak anteroseptal wall to posterior wall strain >130 ms or longitudinal strain delay index >25%. The mean QRS durations in f-QRS and n-QRS groups were not different (P = ns). The incidence of LV dyssynchrony was 15/20 (75%) vs. 5/29 (17%) in two groups (P < 0.01). Two patients died of sudden death in f-QRS group during 2 years follow-up; however, no death in n-QRS group (P < 0.05). Patients in f-QRS group showed worsening LV dyssynchrony in f-QRS group after 2 years follow-up (P < 0.05). Overall, LV function was comparable at baseline (P = ns), but had significantly worsened only in the f-QRS group (P < 0.05). CONCLUSION: The f-QRS complex is significantly associated with LV dyssynchrony in DCM patients and can be used as a reliable index to evaluate ventricular synchrony and predict the prognosis in DCM patients with narrow QRS complexes.