Introduction: This study evaluates the correlation between ejection fraction (EF) and many biochemical cardiac markers in patients with left bundle branch block (LBBB). The heart's ability to pump blood can be negatively affected by LBBB, a frequent conduction defect. An essential measure of cardiac function, EF, is the amount of blood pushed out of the left ventricle during each contraction. Aim: This study aims to better understand the relationships between EF and cardiac biochemical markers in individuals with LBBB and the biological implications of these findings. Material and methods: A case-control study was performed with 140 participants (70 LBBB patients and 70 healthy controls).