In order for the heart to contract, an action potential must be generated at the sinoatrial node. If this signal fails to reach the Purkinje fibers, what will be the result?

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Just like skeletal and smooth muscle, cardiac muscle must have an electrical signal, or action potential, in order to contract. This means that the heart can contract on its own without the brain telling it to contract. This is possible due to the sinoatrial (SA) node, which can spontaneously initiate an action potential. This action potential is initiated in the right atrium where the SA node is located and disperses throughout the heart allowing muscle contraction to occur.
Purkinje fibers are networks of fibers that are involved in relaying the electrical signal to the ventricles. If an electrical discharge does not reach the Purkinje fibers, they will take over as pacemaker cells to allow the continued contraction of the ventricles. However, the Purkinje fibers are only able to fire between 20-40 beats per minute, while the SA node is capable of firing 60-100 beats per minute.
Note: If the Purkinje fibers were not able to fire, then the ventricles would not contract at all.

In Order for the Heart to Contract, an Action Potential