From the Guidelines
Mobitz Type 2 heart block, even when asymptomatic, typically requires prompt cardiology consultation and often permanent pacemaker implantation. This recommendation is based on the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay, which suggests that permanent pacing is recommended for patients with acquired second-degree Mobitz type II atrioventricular block, regardless of symptoms 1. The guideline assigns a Class I recommendation with a Level of Evidence B-NR for this indication, highlighting the importance of prompt intervention to prevent potential complications.
Key Considerations
- The underlying pathophysiology of Mobitz Type 2 block involves disease in the His-Purkinje system, which carries a high risk of progression to complete heart block with minimal warning.
- Patients with Mobitz Type 2 block should be monitored closely, potentially with telemetry in an inpatient setting depending on the clinical context.
- Temporary pacing may be needed if the patient develops symptoms or hemodynamic instability.
- Medications that slow conduction through the AV node (beta-blockers, calcium channel blockers, digoxin) should be avoided or discontinued if possible, as they can exacerbate the condition.
Patient Education
- Patients should be educated about symptoms that warrant immediate medical attention, including syncope, pre-syncope, severe dizziness, or chest pain.
- The importance of prompt cardiology consultation and potential permanent pacemaker implantation should be emphasized to ensure timely intervention and prevent potential complications, as recommended by the 2019 ACC/AHA/HRS guideline 1.
From the Research
Mobitz Type 2 Asymptomatic
- Mobitz type II second-degree atrioventricular block is a form of "incomplete" heart block, in which some, but not all, atrial beats are blocked before reaching the ventricles 2.
- The site of the block in Mobitz type II is almost always below the AV node, and it is more likely to progress to complete heart block and Stokes-Adams arrest 2.
- The diagnosis of Mobitz type II block requires a stable sinus rate, and an unchanged PR interval after the block is a key characteristic 3.
- A 2:1 AVB cannot be classified in terms of type I or type II AVB, and atypical forms of Wenckebach AVB may be misinterpreted as Mobitz type II AVB 3.
- Correctly identified Mobitz type II AVB is invariably at the level of the His-Purkinje system and is an indication for a pacemaker 3.
- Mobitz type II second-degree atrioventricular block must be distinguished from other "causes of pauses," such as nonconducted premature atrial contractions and atrial tachycardia with block 2.