Left anterior hemiblock is an abnormality of the electrical conduction system that in general has no long-term effects.
For some insight, there is a two groups (bundles) if conducting pathways to activate the left ventricle contraction (pumping phase). One group that moves down the septum wall (wall separating left and right side of the heart) and the electrical impulse activate the posterior side of the left ventricle and the other group the anterior (front side of tge ventricle). The right side for ventricle activation has its own electrical impulses.
Left Anterior Hemiblock occurs when a cardiac electrical impulse spreads first through the left posterior (group) causing a delay in activation of the anterior and lateral walls of the left ventricle which are normally activated via the left anterior group. Although there is a delay or block in activation of the left anterior fascicle there is still preservation of initial left to right septal activation as well as preservation of the inferior activation.
In general, finding a hemiblock should trigger a search for underlying heart disease. Often none is found, in which case the hemiblock can be ignored. If condition warrants and there a few conditions in which people with bundle branch block require pacemakers.
The discoordination causes a loss of the heart's efficiency, but a person with a normal heart, the condition is of little medical significance. But for instance a person with a dilated cardiomyopathy this loss of efficiency can be critical, and can contribute greatly to symptoms of heart failure. Worst case scenario.
Hope this helps, and if you have any further questions or comments you are welcome to respond. Thanks for sharing, take care.