Background: Nowadays, many patients with cardiovascular diseases require pacemaker implantation that is associated with few complications such as cardiac and valvular insufficiency. This study aims to compare the development of tricuspid and mitral regurgitation in right ventricular outflow tract (RVOT) and right ventricular apex (RVA) pacing.

Materials and Methods: In this single-blind clinical trial, 164 candidates for permanent pacemaker (PPM) implantation due to sick sinus syndrome or atrioventricular block were randomly divided into 2 equal groups to receive either RVOT or RVA pacing. Patients with heart failure or valvular diseases were excluded from the study. Pre and post-procedural echocardiography after 6 months were performed and the results were compared for the development of mitral and tricuspid regurgitation and probable changes in the ejection fraction (EF).

Results: Age, gender, pacing mode, and baseline cardiac rhythm did not significantly differ between RVOT and RVA pacing groups. The incidence of mitral regurgitation was significantly higher in the RVA group (p=0.033), whereas the incidence of tricuspid regurgitation was similar in both groups (p>0.05). There was a trend toward less tricuspid regurgitation in the RVOT group however, it was not statistically significant. Ejection fraction was not significantly different between the study groups.

Conclusion: It seems that the incidence of mitral regurgitation in RVA pacing is significantly higher than RVOT although this needs further investigation in future studies.