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Background: Right ventricular apical pacing can cause dyssynchronous activation of the ventricles, increase sympathetic activation, cause abnormalities in myocardial perfusion, worsen cardiac output and endothelial function, and may be associated with adverse cardiovascular effects. The use of rennin-angiotensin system blockers (RASBs) may be beneficial in counteracting these potentially harmful effects of right ventricular pacing. Objective: To explore the impact of RASB use on the outcome in patients with right ventricular pacemakers implanted for complete atrioventricular (AV) block. Methods: Patients implanted with right ventricular pacemakers for complete AV block between 1994 and 2009 were identified from the Tayside Pacing Registry. Cox proportional hazards model was used to assess differences in all-cause mortality and congestive heart failure hospitalizations for those receiving RASB during follow-up, adjusted for confounding variables. We also performed 2 sensitivity analyses--a propensity score-matched analysis and time-dependent analyses--to minimize bias. Results: Eight hundred twenty patients (57% men; median age 73 years; range 22-103 years) received pacemakers for complete AV block between 1994 and 2008 (54% dual-chamber pacemaker and 46% ventricular demand pacemaker). Two hundred seventy-eight (34%) patients had received RASBs. Mean follow-up was 4.9 ± 4.6 years, with 540 (65%) deaths. RASB use was independently associated with significantly reduced mortality (adjusted hazard ratio 0.67; 95% confidence interval 0.47-0.94; P = .017) and reduced heart failure hospitalization (adjusted hazard ratio 0.42; 95% confidence interval 0.17-0.92; P <.001). Conclusions: This study suggests that RASBs may confer outcome benefits in patients with right ventricular pacemakers implanted for complete AV block. [ABSTRACT FROM AUTHOR]