Myocardial work by speckle-tracking echocardiography in pacemaker patients according to pacing site: a prospective study

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The optimal lead position for right ventricle (RV) pacing is still a matter of debate. Several studies compared 2D-echocardiography left ventricle ejection fraction (LVEF) and LV global longitudinal strain (LVGLS) by speckle-tracking imaging (STI). However, these parameters present limitations, such as load dependency. Recently, myocardial work (MW) has emerged as an alternative tool for myocardial systolic function assessment. Purpose To compare LV MW and LVGLS between patients with RV outflow tract/septum pacing (Group1) and RV apical pacing (Group2). Methods Prospective single-center study of patients with permanent pacemaker (PMK) followed at our cardiac device’s outpatient clinic between july and november of 2022. Patients were divided into two groups according to RV pacing site. Moderate/severe valvular disease, LVEF<50%, segmental wall-motion abnormalities, pulmonary hypertension, cardiomyopathies, or RV dysfunction were exclusion criteria. STI-based LVGLS analysis and MW parameters were obtained (GWI:Global Work Index; GCW:Global Constructive Work; GWW:Global Wasted Work; GWE:Global Work Efficiency). RV pacing was required at the moment of imaging. A 12-lead ECG was also performed. Blood pressure (BP) was simultaneously measured. Results Our cohort comprised 30 patients in group 1 and 25 patients in group 2. The 2 groups were well-matched, except for the median time since PMK implantation, which was significantly higher in Group2 (5.3years vs 0.9years, p<0.001). The QRS was significantly narrower in Group1 (Group1:129ms±9 vs Group2:165ms±15, p<0.001). LVEF was similar in both groups (Group1:58%±7.5 vs Group2:60%±7.5, p = NS). Likewise, both systolic and diastolic BP were comparable (p = NS), but LVGLS was significantly higher in Group1 (15±3.3 vs 13±3.7, p = 0.043). Except for GWI which was also significantly higher in Group1 (1553mmHg%±581 vs 1238mmHg%±516, p = 0.040), no significant differences were found in the other parameters of MW among the groups (all p = NS). Conclusion Our results point to LVGLS being significantly lower in the group of RV apical pacing. Despite most parameters of MW didn’t differ between groups, GWI also showed significant impairment. These findings should be regarded as preliminary and further larger studies are needed to ascertain the value of this new tool in understanding the impact of pacing depolarization site on LV mechanics.