From the Guidelines
The primary treatment for Mobitz type II heart block is permanent pacemaker implantation, as it is considered a Class I indication for pacemaker therapy because Mobitz type II blocks often progress to complete heart block and can cause symptoms like syncope, pre-syncope, or heart failure 1. This recommendation is based on the most recent guidelines from the American College of Cardiology, American Heart Association, and Heart Rhythm Society.
While awaiting pacemaker placement, temporary measures may include:
- Atropine (0.5-1 mg IV) for symptomatic bradycardia
- Isoproterenol infusion (2-10 mcg/min titrated to heart rate)
- Temporary transcutaneous or transvenous pacing for hemodynamic instability
Unlike Mobitz type I (Wenckebach), Mobitz type II blocks typically occur below the AV node in the His-Purkinje system, making them less responsive to medication and more likely to progress suddenly to complete heart block 1. The block represents a structural conduction disease rather than a functional abnormality, which explains why permanent pacing is necessary. Patients with Mobitz type II should be monitored in a setting where emergency pacing is available until definitive treatment can be provided.
It is essential to note that the treatment approach may vary depending on the individual patient's condition, and shared decision-making and patient-centered care are endorsed and emphasized in the guidelines 1. However, permanent pacemaker implantation remains the primary treatment for Mobitz type II heart block, and it is crucial to prioritize this treatment to prevent potential complications and improve patient outcomes.
From the FDA Drug Label
Atropine also may lessen the degree of partial heart block when vagal activity is an etiologic factor In some patients with complete heart block, the idioventricular rate may be accelerated by atropine; in others, the rate is stabilized.
The treatment for Mobitz type two heart block may involve atropine (IV), as it can lessen the degree of partial heart block when vagal activity is an etiologic factor, and may accelerate the idioventricular rate in some patients with complete heart block 2. However, it is essential to note that the FDA drug label does not explicitly state that atropine is a treatment for Mobitz type two heart block.
From the Research
Treatment for Mobitz Type Two Heart Block
- The treatment for Mobitz type two heart block may involve the insertion of a permanent pacemaker in symptomatic patients with recurrent episodes 3.
- Intracardiac pacing is not indicated for patients with transient episodes associated with an acute illness 3.
- Drugs that alter autonomic tone, such as atropine, propranolol, and isoproterenol, may influence abnormal His-Purkinje conduction and modulate the atrial pacing cycle length at which type II AV block occurs 4.
- Correctly identified Mobitz type II AV block is invariably at the level of the His-Purkinje system and is an indication for a pacemaker 5.
Important Considerations
- The diagnosis of Mobitz type II block requires a stable sinus rate, and a vagal surge can cause simultaneous sinus slowing and AV nodal block, which can resemble Mobitz type II AVB 5.
- Atypical forms of Wenckebach AVB may be misinterpreted as Mobitz type II AVB, and concealed His bundle or ventricular extrasystoles may mimic both Wenckebach and/or type II AVB (pseudo-AVB) 5.
- The distinction between type II and type I block is descriptive, and the anatomic site of the block and the prognosis are more important to the clinician 6.
Note: Study 7 is not relevant to the treatment of Mobitz type two heart block.