A patient with anterior wall MI develops bifascicular block. What complication should be closely monitored for?

In cases of anterior wall myocardial infarction (MI), the development of bifascicular block indicates a significant involvement of the conduction system. The heart's electrical conduction pathways include the atrioventricular (AV) node and the bundle branches. Bifascicular block typically refers to a blockage in two of the three major conduction pathways, often the right bundle branch and one of the left bundle branches. This can increase the risk of progresses to complete heart block (third-degree AV block) because there’s a higher likelihood that the conduction system is compromised due to ischemia or infarction affecting the areas that control heart rhythm.

The presence of bifascicular block is concerning as it may lead to further conduction disturbances. In the setting of anterior wall MI, which usually implies damage to the left anterior descending artery, the risk of complete heart block is heightened, necessitating close monitoring. Complete heart block can lead to severe bradycardia or asystole, resulting in decreased cardiac output, hypotension, and potential syncope.

Other choices, such as prolonged QTc interval, first-degree AV block, and sinus tachycardia, while they may occur in various contexts of cardiac injury or stress, do not carry the same immediate and life-threatening risk