From the Guidelines
A pacemaker is strongly recommended for individuals with a combination of background RBBB/FD-AVB with alternating LAHB/LPHB due to the high risk of developing complete atrioventricular block and sudden cardiac death. This recommendation is based on the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The presence of alternating LAHB/LPHB indicates unstable conduction in the left bundle branches, which, combined with RBBB, poses a significant risk to the patient's life.
The guideline suggests that patients with conduction disorders, such as BBB or fascicular block with 1:1 AV conduction, should be considered for permanent pacing if they experience syncope or have a high risk of developing complete atrioventricular block 1. Although the provided evidence does not directly address the specific combination of RBBB/FD-AVB with alternating LAHB/LPHB, the general principle of managing conduction disorders with a high risk of progression to complete heart block applies.
Key points to consider in managing these patients include:
- Avoiding medications that slow heart rate, such as beta-blockers, calcium channel blockers, and certain antiarrhythmics
- Staying hydrated
- Seeking immediate medical attention for any symptoms of lightheadedness or syncope
- Close monitoring for signs of worsening conduction disease, such as dizziness, fainting, shortness of breath, or decreased exercise tolerance.
Given the potential for sudden cardiac death, as seen in conditions like Kearns-Sayre syndrome and Anderson Fabry disease, which also involve conduction abnormalities 1, it is prudent to err on the side of caution and recommend a pacemaker for patients with this specific combination of conduction disorders.
From the Research
Combination of Background RBBB/FD-AVB with Alternating LAHB/LPHB
- The combination of background RBBB/FD-AVB with alternating LAHB/LPHB is a complex cardiac condition that may increase the risk of severe symptoms and cardiac complications.
- According to the study 2, patients with trifascicular block, which includes RBBB and LAHB or LPHB, are at high risk of developing severe symptoms such as syncope and Adams-Stokes syndrome, and may require pacemaker implantation.
Risk of Death without Pacemaker
- The study 2 found that patients with trifascicular block who did not receive pacemaker implantation were at higher risk of death due to chronic heart failure.
- However, the study 2 also noted that all patients with trifascicular block and severe symptoms who received pacemaker implantation recovered well, except those with chronic heart failure.
- There is no direct evidence to suggest that someone with a combination of background RBBB/FD-AVB with alternating LAHB/LPHB will definitely die if they do not get a pacemaker, but the risk of severe symptoms and cardiac complications is increased.
Importance of Pacemaker Implantation
- The study 3 found that RBBB with axis deviation is a predictor of pacemaker implantation due to high-degree atrioventricular block or sick sinus syndrome.
- The study 2 also emphasizes the importance of pacemaker implantation in patients with trifascicular block and severe symptoms, as it can significantly improve outcomes and reduce the risk of death.
- However, the decision to implant a pacemaker should be made on a case-by-case basis, taking into account the individual patient's condition and medical history.
Other Relevant Studies
- The studies 4, 5, and 6 provide additional information on the clinical significance of RBBB and its relationship to cardiac disease, but do not directly address the question of mortality without pacemaker implantation in patients with a combination of background RBBB/FD-AVB with alternating LAHB/LPHB.