Abstract 18337: Myocardial Work - A Novel Approach to Investigate the Effects of Right Ventricular Apical Pacing on Left Ventricular Regional Work and Function

Abstract

Background: Right ventricular pacing (RVp) is the most common method of delivering bradycardia pacing, but it is associated with left ventricular (LV) systolic dysfunction (LVSD) in 40% of patients. Animal models have shown that RVp-induced electrical conduction delay leads to dyssynchronous LV activation, resulting in uneven myocardial work (MW) distribution. This work redistribution is believed to trigger adaptive structural remodelling, aiming to achieve a more uniform LV load distribution. Cardiac resynchronisation therapy (CRT) responders demonstrate normalised MW distribution and baseline constructive MW measurements may predict CRT response. However, there is limited evidence on MW in patients with pacemakers. Hypothesis: Long-term RVp in atrioventricular block (AVB) patients with pacemakers may influence MW. Method and Results: One hundred and eighteen patients (mean age 75±10 years; 69% male) with AVB receiving pacemaker therapy were included. Echocardiographic assessment and MW calculations were performed pre- and post-implant. LVSD was defined as LVEF <50%. Among patients, 33 (28%) had LVSD at follow-up (mean time 26±19 months). RVp significantly influenced LVEF (F (1, 18) = 1193, p <0.001), while MW changes were evaluated using repeated measures ANOVA. Constructive work showed a significant interaction effect at the septal wall (F (1, 21) = 8.57, p = 0.008), with no changes observed at the lateral wall (F (1, 51) = 0.93, p = 0.35). However, wasted work exhibited significant interaction effects at both the septal and lateral walls (F (1, 21) = 16.30, p <0.001 vs. F (1, 51) = 7.10, p = 0.014, respectively) (Figure 1). Conclusion: Constructive and wasted work measures at septal and lateral walls are associated with LVSD in patients receiving a pacemaker for AVB. MW may add additional predictive value in identifying people at risk of developing RVp-associated LVSD who may benefit from more complex device therapy such as conduction system pacing, or CRT.