102 Different mechanics of septal and lateral walls and their effects on left ventricular ejection fraction in patients with left bundle-branch block

Abstract

Abstract Funding Acknowledgements Karolina Kupczynska was supported by research grant awarded by the Club 30 of the Polish Cardiac Society Background Left bundle branch block (LBBB) impairs left ventricular (LV) mechanics and can lead to systolic dysfunction. However, LV mechanical changes that differentiate LBBB patients with preserved and reduced LV ejection fraction (LVEF) remain to be clarified. Purpose To measure myocardial work (MWI) and myocardial work efficiency (MWE) of the septal and LV lateral wall in patients with LBBB and various degrees of LV dysfunction using non-invasive strain-derived method. Methods Fifty-eight LBBB patients without coronary artery disease (mean age 65 ± 13 years, 60% male) were divided into 4 groups based on their LVEF according to current recommendations for cardiac chamber quantification (figure A): normal (n= 25), mildly (n= 16), moderately (n= 11), and severely (n= 6) reduced LVEF. Septal and lateral wall MWI and MWE were estimated by LV pressure-strain loop obtained by echocardiography. Results Both MWI (787 mmHg%, 95% CI 651-924 vs 1956 mmHg%, 95% CI 1758-2154; p < 0.0001) and MWE (71%, 95% CI 66-76 vs 85%, 95% CI 82-87; p = 0.0001) were lower in the septum than in the lateral wall. There was a progressive decrease in septal MWI and MWE with the worsening of LVEF (figure B). Conversely, MWI and MWE of the lateral wall were preserved in patients with normal, mildly and moderately reduced LVEF groups. A significant reduction of MWI and MWE in the lateral wall was detected only in patients with severely reduced LVEF (figure C). Conclusion In patients with LBBB, impairment in septal myocardial work escalates according to LVEF loss. Septal dysfunction was compensated by the effective myocardial work of the lateral wall in patients with normal, mildly and moderately reduced LVEF. Mechanical dysfunction of the lateral wall was associated with severe reduction of LVEF. Abstract 102 Figure.