Mechanism of syncope in patients with bundle branch block and negative electrophysiological test
Abstract
BACKGROUND: In patients with syncope and bundle branch block (BBB), syncope is suspected to be attributable to a paroxysmal atrioventricular (AV) block, but little is known of its mechanism when electrophysiological study is negative. METHODS AND RESULTS: We applied an implantable loop recorder in 52 patients with BBB and negative conventional workup. During a follow-up of 3 to 15 months, syncope recurred in 22 patients (42%), the event being documented in 19 patients after a median of 48 days. The most frequent finding, recorded in 17 patients, was one or more prolonged asystolic pause mainly attributable to AV block; the remaining 2 patients had normal sinus rhythm or sinus tachycardia. The onset of the bradycardic episodes was always sudden but was sometimes preceded by ventricular premature beats. The median duration of the arrhythmic event was 47 seconds. An additional 3 patients developed nonsyncopal persistent III-degree AV block, and 2 patients had presyncope attributable to AV block with asystole. No patients suffered injury attributable to syncopal relapse. CONCLUSIONS: In patients with BBB and negative electrophysiological study, most syncopal recurrences have a homogeneous mechanism that is characterized by prolonged asystolic pauses, mainly attributable to sudden-onset paroxysmal AV block.
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The traditional paradigm attributes syncope in bifascicular block primarily to progression to intermittent high-grade atrioventricular block.
“The traditional paradigm attributes syncope in BFB primarily to progression to intermittent high-grade AVB [12].”
From Empiric pacing in unexplained syncope and bifascicular block: A systematic review and meta-analysis (2026) · cites this paper as [12]
In patients with bundle branch block in whom paroxysmal AV block is likely despite negative complete EPS, an arrhythmia was observed in 41% under ILR observation, being paroxysmal AV block in 70%.
“Patients with bundle branch block (BBB) in whom paroxysmal atrioventricular (AV) block is likely despite negative complete EPS: an arrhythmia was observed in 41% of these patients (being paroxysmal AV block in 70%) under ILR observation, based on pooled data from three studies 174,187,188”
From 2018 ESC Guidelines for the diagnosis and management of syncope (2018) · cites this paper as [187]
Approximately one-third of patients with a negative EPS in whom an ILR was implanted developed intermittent or permanent AV block on follow-up.
“Conversely, approximately one-third of patients with a negative EPS in whomanILR was implanted developed intermittent or permanent AV block on follow-up. 187”
From 2018 ESC Guidelines for the diagnosis and management of syncope (2018) · cites this paper as [187]
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References 13 · Cited by 328
- Authors
- Brignole, M., Menozzi, C., Moya, A., Garcia-Civera, R., Mont, L., Alvarez, M., Errazquin, F., Beiras, J., Bottoni, N., Donateo, P., & on behalf of the International Study on Syncope of Uncertain Etiology (ISSUE) Investigators
- Affiliations
- Hospital Clínico Universitario de Valencia (ES)
- From the Departments of Cardiology, Ospedali Riuniti (M.B., P.D.), Lavagna, Italy; Ospedale S. Maria Nuova (C.M., N.B.), Reggio Emilia, Italy; Hospital Vall d’Hebron (A.M.), Barcelona, Spain; Hospital Clinico Universitario (R.G.-C.), Valencia, Spain; Hospital Clinico (L.M.), Barcelona, Spain; Hospital Virgen de las Nives (M.A.), Granada, Spain; Hospital Virgen del Rocio (F.E.), Sevilla, Spain; and Hospital Xeral de Vigo (J.B.), Vigo, Spain.
- Venue
- Circulation
- Published
- 2001-10-23
- Volume
- 104
- Issue
- 17
- Pages
- 2045-2050
- ISSN
- 0009-7322 (ISSN-L)
- 1524-4539
- OpenAlex
- W2108007677
- Cited by
- 328
- References
- 13
- Citations by year
- 2026: 9 · 2025: 3 · 2024: 3 · 2023: 4 · 2022: 16 · 2021: 15 · 2020: 15 · 2019: 6 · 2018: 17 · 2017: 18 · 2016: 8 · 2015: 11 · 2014: 17 · 2013: 24 · 2012: 14
- FWCI
- 10.23
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Circulation (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Surgery › Cardiovascular Syncope and Autonomic Disorders
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac electrophysiology and arrhythmias
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac pacing and defibrillation studies
- Keywords
- syncope, bundle branch block, paroxysmal atrioventricular block, implantable loop recorder, complete heart block, premature ventricular contractions, syncope recurrence
- MeSH terms
- Aged, Bundle-Branch Block, Female, Follow-Up Studies, Heart Block, Heart Conduction System, Humans, Male, Predictive Value of Tests, Prospective Studies, Syncope, Electrocardiography, Ambulatory, Defibrillators, Implantable, Disease-Free Survival, Tilt-Table Test, Electrophysiologic Techniques, Cardiac
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