ABSTRACT
OBJECTIVE: The impact of right ventricular (RV) apical pacing on very long-term cardiac prognosis is little known. In this study, we retrospectively evaluated the relationship between RV apical pacing and cardiovascular events (CEs) in patients with sick sinus syndrome (SSS) and left ventricular ejection fraction (LVEF) >35%. METHODS: Total of 532 consecutive pacemaker recipients with SSS and LVEF >35% were divided into two groups according to the mean cumulative per cent RV apical ventricular pacing (mean %VP) (<50%; non-VP group vs ≥50%; VP group) and occurrence of CE was compared using Kaplan-Meier analysis between two groups. Cox hazard model was used to assess predictors of CE after adjusting explanatory variables such as age, atrial fibrillation (AF) and structural heart disease (SHD). RESULTS: Mean %VP was 86.0% and 8.2% in VP and non-VP groups, respectively (p<0.001). During mean follow-up of 13.4±7.0 years, CE occurred in 131 patients and more frequently in VP than non-VP group (p<0.001). However, the VP group was no longer associated with CE after taking into account other variables in multivariate analysis, which revealed AF (HR (HR)=2.08), SHD (HR=4.97), low LVEF (HR=0.98 for every 1% increase) and high age (HR=1.03 for every year of age) were independent predictors for CE. Regarding patients with SHD and/or AF and those aged ≥75 years, Kaplan-Meier curves showed both groups had similar prognosis. CONCLUSIONS: Cardiac prognosis of patients with RV apical pacing was poor, but after adjusting for other predictors of CE, RV apical pacing was not a prognostic factor in patients with SSS with LVEF >35%.