Objectives Ventricular conduction block (VCB) identified on a 12-lead electrocardiogram are associated with poor outcomes in patients with known cardiac diseases. The prognostic implications of VCB patters in dilated cardiomyopathy (DCM) patients, however, need to be evaluated. The purpose of this study was to determine all-cause mortality in DCM with VCB.
Methods An observational cohort study was undertaken of patients from 2003 to 2011, 1119 patients were enrolled with median follow-up of 3.5 years. Standard demographics, echocardiography and routine blood tests were obtained shortly after admission. All patients were then divided into LBBB, RBBB, intraventricular conduction delays (IVCD) and narrow QRS groups. Outcome was assessed with all-cause mortality.
Results Of the 1119 patients, 19.8% (n = 221) had LBBB, 7.3% (n = 82) had RBBB, 6.0% (n = 67) had IVCD, 66.9% (n = 749) had narrow QRS. All-cause mortality rates were highest in patients with IVCD (47.8%, n = 32), intermediate in those with RBBB (32.9%, n = 27) and LBBB (27.1%, n = 60), and lowest in those with narrow QRS (19.9%, n = 149), a significant difference in all-cause mortality risk among the VCB groups and narrow QRS group (log-rank χ2 = 51.564, P < 0.001). In addition, significant mortality differences were also demonstrated between the DCM patients with VCBs and pulmonary hypertension (PH) compared with those without PH (37.9% vs. 20.9%, log-rank χ2 = 27.087, P < 0.001). Presence of RBBB, IVCD, PH, left atrium diameter and NYHA functional class were the independent predictors of all-cause mortality in DCM patients.
Conclusions VCB, in particular IVCD, predicts mortality in DCM, and that RBBB and IVCD but not LBBB are independent predictors of mortality.