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      Time Relation between a Syncopal Event and Documentation of Atrioventricular Block in Patients with Bifascicular Block: Clinical Implications

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          Abstract

          Background: Transient high-degree atrioventricular (AV) block is a common cause of syncope in patients with bifascicular block (BFB) but the intermittent nature of AV block makes ECG documentation a challenge. A sensitive and safe tool to investigate BFB patients with syncope would be a bradycardia-detecting pacemaker, which provides a possibility of studying the time relation between the index syncopal episode and the development of high-degree AV block. Methods: Twenty-seven patients with BFB and syncope were studied prospectively. All patients received a single-chamber ventricular-based pacemaker with bradycardia-detecting ability. A bradycardia episode was defined as a heart rate of <30 beats/min lasting ≧6 s. Results: During a median follow-up of 60 months, a bradycardia event was detected in 14 patients (52%), of whom 13 also had documented high-degree AV block on ECG. The median time between the syncopal episode and the first pacemaker-detected bradycardia event was 5 months and after an additional median time of 6 months, high-degree AV block was documented on the ECG. In 10 of 13 patients (77%) high-degree AV block was documented within 24 months of the syncopal episode corresponding to an annual incidence of 19% during the first 2 years of follow-up in the study population. Conclusion: In this group of BFB patients a syncopal episode was highly predictive of the development of high-degree AV block within 24 months, justifying pacemaker therapy without prior ECG verification.

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          Most cited references 15

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          Mechanism of syncope in patients with bundle branch block and negative electrophysiological test.

           ,  M Brignole,  N Bottoni (2001)
          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. 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. 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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            Natural history of "high-risk" bundle-branch block: final report of a prospective study.

            We conducted a prospective study in which 554 patients with chronic bifascicular and trifascicular conduction abnormalities were followed for an average of 42.4 +/- 8.5 months. Heart block occurred in 19 patients, and 17 were successfully treated. The actuarial five-year mortality from an event that could conceivably have been a bradyarrhythmia was 6 per cent (35 per cent from all causes). Of the 160 deaths 67 (42 per cent) were sudden; most of these were not ascribable to bradyarrhythmia but to tachyarrhythmia and myocardial infarction. Mortality was higher in patients with coronary-artery disease (P less than 0.01) and congestive heart failure (P less than 0.05). Patients in whom syncope developed before or after entry into the study had a 17 per cent incidence of heart block (2 per cent in those without syncope)(P less than 0.05); however, no single variable was predictive of which patients were at high risk of death from a bradyarrhythmia. The predictors of death were increasing age, congestive heart failure, and coronary-artery disease; the predictors of sudden death were coronary-artery disease and increasing age. The risks of heart block and of death from a bradyarrhythmia are low; in most patients, heart block can be recognized and successfully treated with a pacemaker.
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              Value of the H-Q interval in patients with bundle branch block and the role of prophylactic permanent pacing

              His bundle electrograms were obtained in 313 patients with chronic bundle branch block who were followed for a mean period of almost 3 years. The infranodal conduction time (H-Q interval) was less than 55 ms in 97 patients (Group I), 55 to 69 ms in 99 patients (Group II), and greater than or equal to 70 ms in 117 patients (Group III). There was a higher incidence of organic heart disease in patients in Group III, but the groups were otherwise comparable. On follow-up study, mortality and the incidence of sudden death were similar among the groups, but patients in Group III had a greater incidence of progression to high degree atrioventricular block (HDB) than did those in Groups I and II (14 of 117 [12%] versus 4 of 97 [4%] and 2 of 99 [2%], p less than 0.01, respectively). High degree block was found in 4 of 17 (24%) patients with an H-Q interval (H-Q) greater than or equal to 100 ms. Sixty-two patients underwent permanent prophylactic pacemaker insertion at the discretion of the referring physician and were compared with 231 patients who did not. Paced patients had a higher incidence of transient neurologic symptoms and prolonged H-Q, but the groups were otherwise comparable. On follow-up study, mortality and the incidence of sudden death were similar among the groups, but symptom relief was significantly more common among patients with pacemakers. In conclusion, in our population (1) H-Q greater than or equal to 70 ms was an independent risk factor for progression to HDB, (2) H-Q greater than or equal to 100 ms identified a subgroup at particularly high risk, and (3) prophylactic pacemakers relieved neurologic symptoms but did not prolong life.
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                Author and article information

                Journal
                CRD
                Cardiology
                10.1159/issn.0008-6312
                Cardiology
                S. Karger AG
                0008-6312
                1421-9751
                2007
                August 2007
                06 October 2006
                : 108
                : 2
                : 138-143
                Affiliations
                Departments of Cardiology, aKarolinska Institute, South Hospital, Stockholm, bSahlgrenska University Hospital, Gothenburg, and cÖrebro University Hospital, Örebro, Sweden
                Article
                96038 Cardiology 2007;108:138–143
                10.1159/000096038
                17028424
                © 2007 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 3, Tables: 2, References: 27, Pages: 6
                Categories
                Original Research

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