From the Guidelines
Permanent pacemaker implantation is recommended for patients with 2:1 atrioventricular (AV) block and left bundle branch block (LBBB) due to the high risk of progression to complete heart block and significant conduction system disease. This condition suggests underlying structural heart disease and increased likelihood of left ventricular systolic dysfunction, as indicated by the presence of LBBB on electrocardiogram 1. Initial management may include temporary transvenous pacing if the patient is hemodynamically unstable, with symptoms such as syncope, pre-syncope, or heart failure.
Key Considerations
- Discontinuation of medications that slow AV conduction, such as beta-blockers, calcium channel blockers, and digoxin, is crucial in managing these patients.
- Atropine (0.5-1 mg IV) can be administered as a temporizing measure in bradycardic patients, and isoproterenol infusion (starting at 2-10 mcg/min) may be used in emergency situations to increase heart rate until definitive therapy is available.
- The choice of permanent pacemaker type depends on the patient's underlying rhythm and ventricular function, but typically a dual-chamber pacemaker (DDD) is preferred to maintain AV synchrony.
- In patients with reduced ejection fraction (<35%), a cardiac resynchronization therapy (CRT) device may be considered to improve cardiac output and reduce heart failure symptoms, as techniques that provide more physiologic ventricular activation are preferred to right ventricular pacing to prevent heart failure 1.
Patient-Centered Care
- Shared decision-making and patient-centered care are endorsed in the management of patients with bradycardia who have indications for pacemaker implantation, with treatment decisions based on the best available evidence and on the patient’s goals of care and preferences 1.
- Patients with decision-making capacity or their legally defined surrogate have the right to refuse or request withdrawal of pacemaker therapy, even if the patient is pacemaker dependent, which should be considered palliative, end-of-life care, and not physician-assisted suicide 1.
From the Research
Management of 2:1 AV Block with Left Bundle Branch Block
The management of a patient with 2:1 atrioventricular (AV) block and left bundle branch block (LBBB) is a complex clinical problem.
- The risk of developing high-degree AV block in patients with pre-existing bundle branch block and LBBB is significant, particularly in the setting of acute myocardial infarction 2.
- Prophylactic pacemaker insertion is recommended in high-risk groups, such as patients with pre-existing bifascicular block and anterior wall infarction, or those with LBBB and acute anterior wall infarction 2.
- In patients with bifascicular block and syncope, empiric permanent pacing may reduce major adverse events compared to implantable cardiac monitoring 3.
- However, the risk of progression to high-degree AV block and the need for pacemaker insertion must be carefully evaluated on a case-by-case basis, taking into account the individual patient's clinical characteristics and underlying heart disease 4.
- The use of transcutaneous pacing in the perioperative setting may be safe and effective in patients with chronic bifascicular block or LBBB and additional first-degree AV block, but its routine prophylactic use is not justified 5.
- Close monitoring and follow-up of patients with LBBB and 2:1 AV block are crucial, as they are at increased risk of complete AV block and poor prognosis 6.