The influence of low atrial septal pacing on atrial synchrony and function in patients with sick sinus syndrome

Objective To assess the influence of low atrial septal pacing on atrial electrical, mechanical synchrony and function in patients with sick sinus syndrome (SSS) . Methods One hundred patients with sick sinus syndrome and permanent pacing indication were enrolled from June 2015 to September 2016 at the First Affiliated Hospital of University of Science and Technology of China, and divided into non-interatrial block group (P≤120 ms) and interatrial block group (P>120 ms) according to the duration of P wave, then randomly divided into non-interatrial block with right atrial appendage pacing group (A) , non-interatrial block with low atrial septal pacing group (B) , interatrial block with right atrial appendage pacing group (C) , and interatrial block with low atrial septal pacing group (D) . The electrocardiogram and echocardiography were used to evaluate the influence of selective atrial pacing on atrial electrical, mechanical synchrony and function. Results The P wave duration [ (130.4±8.3) ms vs. (118.2±7.8) ms, P<0.01], and dispersion [ (29.8±7.4) ms vs. (26.2±5.1) ms, P<0.01) ], Tmsv-16-SD[ (134.2±35.1) ms vs. (110.9±21.7) ms, P<0.01] Tmsv-16-SD%[ (17.4±4.3) % vs. (14.3±2.7) %, P<0.01], left atrial ejection fraction (LAEF) [ (41.6%±6.6%) vs. (44.7%±7.5%) , P<0.01], strain (mSs) [ (39.9%±9.1%) vs. (41.2%±8.5%) , P<0.01], strain rate (mSRs) [ (3.6±0.7) s-1 vs. (3.9±0.7) s-1, P<0.01] and strain rate (mSRa) [ (-2.8±0.4) s-1 vs. (-3.1±0.5) s-1, P<0.01]were improved by low atrial septal pacing in patients with interatrial block and SSS. The P wave durationand dispersion, Tmsv-16-SD and Tmsv-16-SD% were increased by right atrial appendage pacing in SSS patients (P<0.05) , LAEF, mSs, mSRs, mSRe and mSRa were decreased by right atrial appendage pacing in patients with interatrial block and SSS (all P<0.01) . The P wave duration, dispersion and Tmsv-16-SD, Tmsv-16-SD% were highly correlated (all P<0.01) . Conclusion In patients with SSS and interatrial block, low atrial septal pacing could improve the atrial electrical, mechanical synchrony and function. Key words: Atrial septum; Sick sinus syndrome; Interatrial block; Pacing