Is right ventricular outflow tract pacing superior to right ventricular apex pacing? A long-term follow-up study

Background: We report the long-term results of our follow-up study, which compared right ventricular outflow tract (RVOT) pacing and right ventricular apex (RVA) pacing in terms of left and right ventricular function, synchrony, cardiac remodeling, the degree of valve regurgitation and clinical outcomes. Methods: Ninety-six patients with completed or high-degree atrio-ventricular block were prospectively enrolled and randomized to receive RVOT (group A, n=48) or RVA (group B, n=48) pacing.The follow-up were performed every 6 months in the first year, then every 1-2 years till the next implantation or for 8 years if the pacemaker was in normal condition. 2D, color Doppler, Tissue Doppler Imaging (TDI), and real-time three-dimensional echocardiography (RT3DE) were performed. Heart failure hospitalization and all-cause death rate were calculated. Results: Eighty-seven patients had extended follow-up, including 43 in group A and 44 in group B, with a mean duration of 7.0±1.0 years (3.1-8.3 years). LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV) in Group B were larger than those of group A (both P<0.05). There were no statistical differences of LVEF between the two groups. However, the mean myocardial systolic (Sm) and global longitudinal strain (GLS) of Group B were significantly lower than those of group A (both P<0.05). There were no statistical differences in the risk of hospitalization for heart failure and all-cause death rate. Conclusions: RVOT pacing had advantages in the protection of left ventricular systolic function and remodeling but was not superior to RVA pacing in valve regurgitation and clinical outcomes. Sm and GLS were sensitive in detecting early systolic dysfunction.