From the Guidelines
Management of a patient with 2:1 heart block requires immediate intervention with permanent pacemaker implantation, especially if the block is below the AV node (infranodal), as recommended by the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Key Considerations
- The presence of symptoms such as dizziness, syncope, chest pain, or hypotension necessitates immediate intervention.
- Asymptomatic patients with stable vital signs may be closely monitored with continuous cardiac telemetry.
- Underlying causes such as medication effects, electrolyte abnormalities, or myocardial ischemia should be identified and addressed.
- The decision to implant a pacemaker depends on the presence of symptoms related to bradycardia or ventricular arrhythmias and their prognostic implications, as stated in the 2007 European Society of Cardiology guidelines for cardiac pacing and cardiac resynchronization therapy 1.
Recommendations
- Permanent pacemaker implantation is recommended for patients with acquired second-degree Mobitz type II atrioventricular block, high-grade atrioventricular block, or third-degree atrioventricular block not caused by reversible or physiologic causes, as per the 2019 ACC/AHA/HRS guideline 1.
- For patients with 2:1 heart block, permanent pacemaker implantation is often indicated, especially if the block is below the AV node (infranodal), as suggested by the 2013 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
- The urgency of pacemaker placement depends on symptoms, with immediate placement needed for symptomatic patients and elective placement possible for stable patients.
Important Considerations
- The site of AV block, whether intra- or infra-Hisian, should be determined to guide management decisions, as discussed in the 2013 ACCF/AHA/HRS focused update 1.
- Reversible causes of AV block, such as electrolyte abnormalities, should be corrected before considering permanent pacemaker implantation, as recommended by the 2013 ACCF/AHA/HRS focused update 1.
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.
Treatment of 2:1 heart block may involve the use of atropine, as it may lessen the degree of partial heart block when vagal activity is the cause. However, the effect of atropine on complete heart block is variable, and it may accelerate the idioventricular rate in some patients or stabilize the rate in others 2.
- Key points:
- Atropine may be used to treat 2:1 heart block
- Effect of atropine on complete heart block is variable
- Atropine may accelerate or stabilize the idioventricular rate in complete heart block 2
From the Research
Management of 2:1 Heart Block
- The management of 2:1 heart block depends on the underlying cause and the patient's symptoms 3.
- In patients with 2:1 heart block, a temporary transvenous pacemaker (TTVP) may be used as a bridge to permanent pacemaker implantation, especially in cases where permanent pacemaker implantation is temporarily contraindicated, such as in patients with sepsis 4.
- However, the use of TTVP in patients with new left bundle branch block during transcatheter aortic valve implantation is rarely necessary and may carry additional risks, such as inappropriate pacing and ventricular fibrillation 5.
Temporary Transvenous Pacing
- Temporary transvenous pacing can be performed safely and effectively in the intensive care unit (ICU) or in the catheterization laboratory, with no significant difference in complication rates between the two settings 6.
- The choice of location for temporary transvenous pacing depends on the patient's condition and the availability of resources, and should be made on a case-by-case basis.
Risk Factors for Disease Progression
- Patients with 2:1 heart block are at increased risk for progressing to complete heart block or requiring a pacemaker if they have second-degree block at maximum sinus rate, a below normal average heart rate, or 2:1 block on initial ECG 7.
- These patients should be closely monitored and managed accordingly to prevent disease progression and improve outcomes.