From the Guidelines
Bifascicular block patients who are asymptomatic do not require specific treatment, but regular cardiac monitoring is recommended to detect progression to complete heart block, whereas symptomatic patients or those with intermittent high-degree AV block may require permanent pacemaker implantation, as indicated by the most recent guidelines 1.
Key Considerations
- Bifascicular block refers to ECG evidence of impaired conduction below the AV node in the right and left bundles, and it can be associated with an increased risk of progression to complete heart block.
- The decision for pacemaker placement should be based on symptoms and risk assessment rather than the presence of bifascicular block alone, as stated in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
- Patients with bifascicular block who experience syncope, presyncope, or documented progression to higher-degree block should be evaluated promptly, and permanent pacing may be indicated in these cases.
- Regular ECG monitoring and ambulatory monitoring, if symptoms suggest intermittent conduction problems, are essential for managing patients with bifascicular block.
Management Approach
- Asymptomatic patients with bifascicular block should undergo regular cardiac monitoring to detect progression to complete heart block.
- Symptomatic patients or those with intermittent high-degree AV block should be evaluated for permanent pacemaker implantation, considering the latest guidelines and recommendations 1.
- The use of electrophysiological studies may be helpful in evaluating and directing the treatment of inducible ventricular arrhythmias in patients with bifascicular block, as mentioned in the 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
Important Factors
- The PR and HV intervals have been identified as possible predictors of third-degree AV block and sudden death in patients with bifascicular block, although their predictive value is limited, as discussed in the ACC/aha/hrs 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
- The presence of bifascicular block itself does not necessarily determine the need for pacemaker placement, but rather the presence of symptoms and risk assessment, as emphasized in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
From the Research
Bifascicular Block Overview
- Bifascicular block (BFB) is a condition where there is a blockage in two of the three fascicles of the heart's electrical conduction system.
- Studies have shown that patients with BFB and syncope (fainting spells) may benefit from permanent cardiac pacing 2, 3, 4, 5, 6.
Management of Bifascicular Block
- Empiric pacemaker implantation has been shown to reduce the risk of syncope recurrence in patients with BFB and unexplained syncope 2, 3, 5.
- Implantable loop recorder (ILR) monitoring is an alternative management strategy, but it may not be as effective in reducing syncope recurrence 2, 3.
- The type of bundle branch block morphology does not seem to affect the outcome of patients with syncope and BFB who receive pacemaker implantation 6.
Outcomes of Patients with Bifascicular Block
- Studies have reported a significant reduction in major adverse events, including syncope, bradycardia, and device complications, in patients with BFB who receive pacemaker implantation compared to those who receive ILR monitoring 2, 3, 6.
- The annual incidence of rhythm disease development in patients with BFB has been reported to be around 7.4% 4.
- Progression to high-degree atrioventricular block (AVB) is a common occurrence in patients with BFB, with a reported incidence of around 37% 5.