What would most likely happen if the av bundle were damaged?

The action of ventricles will get affected.

Explanation:

In our heart, the proper pumping of blood relies on coordination between the atria and ventricles. AV bundle provides the only electrical connection between the atria and ventricles which ensures the activation of the ventricles after the contraction of atria. If the bundle is damaged, the ventricles will fail to contract and thus pumping of blood in major arteries will be affected. The QRS complex that is seen in the ECG will be either absent or in a changed shape than the normal.