Mobitz II AV block is characterized by sudden unexpected blocked P waves without variation or prolongation of the PR interval.

Electrophysiological studies have proved that Mobitz II block is due to an infranodal His-Purkinje system conduction delay. It generally is associated with a wide QRS complex, except in some patients whose delays are localized within the bundle of His.

Mobitz II block most commonly is caused by acute MI (anterior or inferior).

Withhold AV nodal agents and initiate anti-ischemic therapy when appropriate.
Apply and test transcutaneous pacing patches, even in asymptomatic patients; patients with Mobitz II block have a propensity for progression to complete heart block.
Urgent cardiology consultation is indicated in patients with symptoms and those in whom transcutaneous pacing is tested unsuccessfully; these patients may require placement of a temporary transvenous pacing wire.

Some experts recommend transvenous pacing in all patients with new type II block, although this practice varies from institution to institution.
Patients with unstable cardiac signs also may be treated with atropine, although this is much less likely to be successful in Mobitz II block. Use caution in administering atropine in the setting of a suspected acute MI.

Patients with unstable cardiac signs for whom cardiology consultation is not available in a timely fashion should undergo temporary transvenous pacing wire placement.