Relationship between electrical dyssynchrony and left ventricular function in patients with leadless pacemaker; insights from myocardial work analysis
K Akamatsu, Y Kanzaki, N Nakamura, S Fujioka, M Miyamura, T Ito, H MoritaAbstract
Background
Transvenous right ventricular (RV) apical pacing has been associated with electrical and mechanical left ventricular (LV) dyssynchrony, and impaired LV performance compared with mid-septum pacing. Leadless pacemakers (LP) have been developed to overcome lead-related complications and have been reported to be safe and effective. However, LP implantation sites vary according to cardiac anatomy and operator technique. Although electrical parameters such as QRS duration have been evaluated, the impact of LP positioning on myocardial performance remains unclear.
Purpose
To evaluate whether LP implantation site influence cardiac function using conventional echocardiographic parameters, myocardial work indices derived from LV strain–pressure analysis and LV mechanical dyssynchrony.
Methods
We retrospectively analyzed 24 consecutive patients who underwent LP implantation with right ventriculography during the procedure. RV positions were categorized into basal, mid-septum, and apical segments. Post-implantation echocardiography assessed LV ejection fraction (LVEF), global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Mechanical dyssynchrony was evaluated using septal-lateral work difference (SLWD) and time to peak GLS.
Results
The mean age was 85.1 ± 5.7 years; 16 patients (62.5%) were female. Indications for pacing included atrioventricular block (n=20), sick sinus syndrome (n=3), and bradycardic atrial fibrillation (n=1). No devices were implanted in the basal segment; 12 were positioned in the mid-septum and 12 in the apical segment. QRS duration was similar between the two groups (150.8 ± 15.0 vs. 154.3 ± 12.9 ms, p=0.60). There were no significant differences in LVEF, GLS, or myocardial work indices between the mid-septal and apical groups (LVEF: 53.6 ± 8.1 vs. 53.9 ± 11.8%, p=0.82; GLS: −13.8 ± 3.3 vs. −13.6 ± 4.6%, p=1.00; GWI: 1095 ± 332 vs. 1160 ± 535 mmHg%, p=0.47; GCW: 1521 ± 286 vs. 1600 ± 542 mmHg%, p=0.19; GWW: 302 ± 157 vs. 332 ± 251 mmHg%, p=0.98; GWE: 82.9 ± 8.5 vs. 82.2 ± 9.5%, p=1.00). Similarly, SLWD (870 ± 628 vs. 788 ± 612 mmHg%, p=0.75) and time to peak GLS (75.6 ± 117.9 vs. 68.0 ± 75.2 ms, p=0.95) were comparable. Across all patients, QRS duration was significantly associated with GLS (r = 0.45, p=0.03), indicating impaired myocardial deformation with longer QRS duration. In contrast, QRS duration was not significantly associated with GWI (r = 0.32, p=0.14).
Conclusions
LP implantation in the mid-septum versus apical RV showed no significant differences in myocardial performance or mechanical dyssynchrony. In contrast, QRS prolongation was significantly related to impaired LV deformation, suggesting electrical activation rather than pacing position may play a greater role in early LV mechanics. Larger studies are needed to determine long-term clinical implications.figure