**LBBB** stands for **Left Bundle Branch Block**, and **ECG** stands for **Electrocardiogram**. An LBBB on an ECG indicates a delay or blockage in the electrical impulses traveling through the left bundle branch of the heart's conduction system. This disruption affects how the left ventricle contracts, often causing the heart's electrical pattern to become abnormal. LBBB can be a sign of underlying heart disease, such as cardiomyopathy, hypertension, or coronary artery disease. It may also occur in otherwise healthy individuals. Diagnosis is typically confirmed by specific ECG findings, and further evaluation may be necessary to determine the underlying cause and appropriate treatment.