Assessment of ventricular mechanics by means of myocardial work in patients undergoing physiologic versus right ventricular apical stimulation:a prospective study

Abstract Introduction Left bundle branch area (LBBA) pacing has recently gained widespread acceptance in patients that need pacemaker (PM) stimulation. This type of physiologic pacing may improve ventricular mechanical contraction and reduce the risk of PM-induced left ventricular (LV) dysfunction. Myocardial work (MW), a new tool, based on the analysis of pressure-strain loops, combines the information from speckle tracking strain imaging and non-invasive estimate of LV pressure. It provides a better characterization of LV performance and detection of LV myocardial dysfunction. The aim of this study was to compare MW after PM implantation in LBBA pacing patients (group 1) vs right ventricular apical (RVA, group 2) pacing patients. A control group (group 3) was also enrolled for establishing MW normal values. Methods We studied 30 patients (56% females, age 80 y, IQR 75-84) who underwent PM implantation and had a high probability of a high % of stimulation and 21 controls (57% females, age 79 y, IQR 73-85, p=0.46 and p=0.73 respectively) Patients were prospectively included at two large university hospitals from March 23 until February 24. The mode of stimulation was chosen at their physician’s discretion. Exclusion criteria included LVEF <50% or significant structural or valvular disease. We compared MW parameters between group 1 and group 2 before PM implantation, and 24 hours and 3 months post PM implantation by Kruskal Wallis test. Additionally, we compared MW parameters between group 3 and PM patients after 24 hours using U Mann-Whitney test. Results The % of stimulation was 93%±12. There were no differences in baseline characteristics between group 1 (n=21, 71%) and group 2. At baseline, global work index (GWI), global constructive work (GCW), global wasted work (GWW) or global work efficiency (GWE) did not differ significantly between Group 1 and 2. At 24 hours, all the components of MW significantly improved in Group 1 and 2 and were maintained at 3 months, but the improvement was notably greater in Group 1 (see Table 1). Group 3 and PM patients were similar at baseline (HTN, 86% vs 80%, p=0.7197; DM, 29% vs 30%, p=0.91; coronary artery disease, 14% vs 10%, p=0.68; sinus rhythm, 76% vs 83%, p=0.68). Comparing group 3 and PM at 24 h, GWI, GCW, GWE was significantly higher in group 3 (p=0.0023, p=0.009, p=<0.0001) and GWW was significantly lower (p=<0.0001). Regarding the type of stimulation, MW parameters values in Group 1 were still lower than in Group 3 but clearly better than Group 2 values (see Figure 1). Discussion Our results showed that MW parameters improved to a greater extent in LBBA compared to RVA pacing immediately and after 3 months of PM implantation. Compared to our control group, LBBA pacing group achieved better performance than RVA pacing patients, yielding a more coordinated LV contraction. Nevertheless, more studies are needed to clarify if LBBA pacing causes less PM induced LV dysfunction compared to RVA pacing.