Right ventricular conduction delay by itself cannot cause a heart attack. Right ventricular conduction delay can occur with and without a heart attack. In most instances, right ventricular conduction delay is an isolated abnormality. It can be complete (complete right bundle branch block) or incomplete (incomplete right bundle branch block). Right bundle branch block (RBBB) can occur in a heart attack when the blood supply to right bundle branch is lost due to occlusion of the blood vessel supplying that region. This usually occurs in anterior wall myocardial infarction (heart attack involving the front region of the left ventricle). If a heart attack is associated with right bundle branch block, it may mean more extensive damage to the heart muscle. Rarely, it could be a pre-existing RBBB along with a less extensive heart attack as well.