Delta Increment in Pacing QRS Duration Predicts Cardiovascular Mortality in Patients with Pre-Existing Bundle Branch Block Receiving Permanent Pacemakers.

Abstract

The clinical implication of pre-existing intraventricular conduction disturbance (IVCD) in permanent pacemaker (PPM) recipients is unknown. To explore the clinical outcomes in patients with pre-existing IVCD after implantation of PPMs. A total of 1424 patients who received PPMs were categorized into three groups by pre-procedural electrocardiography: patients without IVCD (n = 1045), patients with right bundle branch block (RBBB) (n = 309), and patients with left bundle branch block (LBBB) (n = 70). The primary outcome was cardiovascular (CV) mortality. Receiver operating characteristic curve analysis was performed to determine the optimal cut-off values of variable in predicting CV mortality. During follow-up, there was no significant difference in CV mortality between patients with and without IVCD. In multivariate analysis, independent predictors of CV mortality were age [hazard ratio (HR): 1.03; 95% confidence interval (95% CI): 1.00-1.05; p = 0.026], history of heart failure [HR: 1.98; 95% CI: 1.19-3.29; p = 0.009], chronic kidney disease [HR: 1.75; 95% CI: 1.11-2.74; p = 0.015] and increment in pacing QRS duration [HR: 1.01; 95% CI: 1.00-1.04; p = 0.038]. Delta increments in pacing QRS duration ≥ 43 msec [HR: 2.91; 95% CI: 1.23-6.83; p = 0.014] in patients with pre-existing RBBB, and ≥ 33 msec [HR: 11.44; 95% CI: 2.03-64.30; p = 0.006] in patients with pre-existing LBBB were independent determinants of CV mortality. There was no difference in CV mortality between patients with or without IVCD. However, wider pacing QRS duration increased the risk of CV mortality in PPM recipients, and delta increment in pacing QRS duration increased the risk of CV mortality in patients with pre-existing IVCD.