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Clinical significance of the pattern of incomplete left bundle branch block with bifascicular block
Insights
Patients with trifascicular block, identified by specific ECG patterns like RBBB with ILBBB, face a significantly higher risk of complete heart block and sudden cardiac death, warranting consideration for prophylactic pacemaker implantation.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Bundle branch blocks (BBB) are common ECG findings.
- Bifascicular blocks, combining RBBB with LAFB or LPFB, are frequently encountered.
- The clinical significance of coexisting ILBBB with bifascicular blocks requires further elucidation.
Purpose of the Study:
- To compare clinical characteristics and long-term outcomes of patients with bifascicular blocks.
- To investigate the prognostic implications of incomplete left bundle branch block (ILBBB) in conjunction with bifascicular blocks.
- To identify patient subgroups at high risk for complete heart block (CHB) and sudden cardiac death (SCD).
Main Methods:
- Comparative analysis of 126 patients (Group I) with RBBB and LAFB/LPFB versus 44 patients (Group II) with RBBB, LAFB/LPFB, and ILBBB.
- Clinical data collection and ECG analysis.
- Long-term follow-up for the development of CHB and SCD.
Main Results:
- Group II patients exhibited significantly higher incidences of heart failure, arrhythmia, and first-degree atrioventricular block.
- CHB developed in 22.7% of Group II patients compared to 3.2% in Group I (p<0.01).
- SCD occurred in 15.9% of Group II patients versus 3.9% in Group I (p<0.01).
Conclusions:
- The presence of ILBBB in patients with bifascicular blocks (trifascicular block) is associated with a poorer prognosis.
- Patients with trifascicular block demonstrate a substantially elevated risk of developing CHB and experiencing SCD.
- Prophylactic pacemaker implantation should be strongly considered for patients identified with trifascicular block due to their high risk profile.
Abstract:
A comparative analysis was carried out of 126 patients (group I) with chronic right bundle branch block (RBBB) and left anterior (LAFB) or left posterior fascicle block (LPFB), and of 44 patients (group II) with the same bifascicular block associated with an ECG pattern of incomplete left bundle branch block (ILBBB). The two groups were found to be clinically different. In group II, heart failure, arrhythmia and first-degree atrioventricular block occurred significantly more frequently. During a mean follow-up period of 1581 +/- 118 days (85-6260 days), complete heart block (CHB) developed in 3.2% of patients in group I and in 22.7% in group II (p less than 0.01). In the same period, sudden cardiac death (SCD) occurred in 3.9% in group I and in 15.9 in group II (p less than 0.01). These results were analysed assuming a quadrifascicular character of the intraventricular conduction system. This made it possible to isolate on the basis of standard ECG findings patients with trifascicular block (group II--RBBB and LAFB or LPFB and septal LBBB) in whom prophylactic pacemaker implantation should be considered in view of high risk of CHB and SCD.