Download The case of chronic bifascicular block: still a worrying

EDITORIAL
Europace (2009) 11, 1140–1141
doi:10.1093/europace/eup245
The case of chronic bifascicular block: still a
worrying ECG finding?
Riccardo Cappato*
Arrhythmias and Electrophysiology Center, IRCCS, Policlinico San Donato, Via Morandi 30, 20097 San Donato Milanese, Milan, Italy
This editorial refers to ‘Long-term mortality predictors in
patients with chronic bifascicular block’ by J. Marti-Almor
et al., on page 1201
The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.
* Corresponding author. Tel: þ39 02 5277 4337, Fax: þ39 02 5560 3125, Email: [email protected]
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2009. For permissions please email: [email protected].
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Diagnosing a chronic bifascicular block commonly raises an
uncomfortable feeling in the cardiologist’s decision process. This
holds especially true when this diagnosis is associated with symptoms such as syncope or pre-syncope. These symptoms are commonly believed to be caused by intermittent or complete AV block
as an evolutional condition in these patients. Although pace-maker
therapy can prevent symptoms recurrence, concerns have been
raised with regard to the ability of anti-bradycardia pacing to
prevent the risk of death.
The ease of recognizing bifascicular block using well-defined
12-lead ECG criteria makes such diagnosis easily doable during
routine clinical evaluation. Once bifascicular block is diagnosed,
maintenance of AV conduction hinges on the continuing integrity
of the remaining third fascicle.1 In early studies, investigators
focused on the capacity to identify predictors of incumbent
failure of the remaining fascicle and its prognostic implication.
The rationale for such a research was based on the assumption
that prophylactic anti-bradycardia pacing would prevent syncope
and death in patients at high risk of evolutional complete AV
block. Several studies conducted to address this question
showed that the risk of complete heart block and death from a
brady-arrhythmia was low.2 – 5 Other studies provided some evidence that, although similar in age to patients with bifascicular
block and concomitant heart disease, patients had lower probability of developing complete AV block or experiencing sudden
or cardiac death if their bifascicular block was ‘idiopathic’.6
Among clinical and electrophysiological indicators of evolutional
complete AV block in patients with chronic bifascicular block,
syncope and HV interval have been investigated with special interest. Despite the intuitive relationship between occurrence of this
symptom and transient or permanent complete AV block,
several studies have shown that other causes may be responsible
of syncope in these patients, including sinus exit block, orthostatic
hypotension, seizure disorders, and ventricular arrhythmias.7 In
patients with bifascicular block, death does not appear to be
higher in patients with than in patients without syncope.7 In
these same patients, a very prolonged HV interval indicates a
higher risk of death; however, increased mortality does not
appear to be associated with evolutional complete AV block, but
with the degree of heart disease.8 Most data concerning the prognostic significance of bifascicular block were collected in the 1970s
and 1980s when co-morbidity was more prevalent than in recent
times.
In this issue, Marti-Almor et al. 9 investigate those parameter that,
when identified at the time of diagnosis, are independently associated with intermediate to long-term mortality of patients with
in-hospital diagnosis of bifascicular block. Between 1998 and
2006, 259 consecutive patients admitted to their institution and
in whom chronic bifascicular block was diagnosed at the time of
hospitalization were prospectively followed for a median of
4.5 years. Their mean age was 73 years, 47% presented with a
structural heart disease, 66% had hypertension, 30% had diabetes,
and another 30% had dyslipaemia. Co-morbidity affected left ventricular ejection fraction to a degree 35% in 12% of patients,
whereas 42% of them presented with impaired renal function.
Finally, there was a high prevalence of prior syncope/pre-syncope
(82% of the whole population). During follow-up, death occurred
in 20% of patients, with cardiac death accounting for only about
one-third (7%) of all deaths. Among several clinical, ECG, and electrophysiologic parameters, only NYHA class 2 and evidence of
renal failure were found to be independent predictors of cardiac
death, whereas no predictor of arrhythmic death was found.
Data from the study by Marti-Almor et al. 9 provide an up-to-date
picture of the prognosis in patients with in-hospital diagnosis of
chronic bifascicular block. Not surprisingly, deaths in this study
occurred at a much lower rate than in previous reports.1 – 7
Although, as mentioned by the authors, differences in co-morbidity
and drug therapies between patients investigated in previous studies
vs. patients in the present study may have contributed to differences
in outcome, other causes may also have played a role. For example,
causes of hospitalization cannot be retrieved in the different studies.
Comparing the role of causes of hospitalization and severity of the
disease causing hospitalization in this study vs. previous studies
may have helped to further comprehend the different outcomes.
Editorial
The selected nature of the patient population, the relatively limited
patient collective and follow-up duration do not allow to expand
the observation of the study by Marti-Almor et al. 9 to all patients
presenting with chronic bifascicular block. The overall risk of
death that patients with chronic bifascicular block and no history
of syncope or hospitalization are running in the present era
remains to be established.
Conflict of interest: none declared.
References
1. Kastor JA. Cardiac electrophysiology hemiblocks and stopped hearts. N Engl J Med
1978;299:249.
2. McAnulty JH, Rahimtoola SH, Murphy E, De Mots H, Ritzmann L, Kanarek PE et al.
Natural history of ‘high-risk’ bundle branch block. N Engl J Med 1982;307:138 –43.
1141
3. Fahy GJ, Pinski SL, Miller DP, McCabe N, Pye C, Walsh MJ. Natural history of
isolated bundle branch block. Am J Cardiol 1996;77:1185 – 90.
4. Smith S, Hayes WL. The prognosis of complete left bundle branch block. Am Heart
J 1965;70:157 –9.
5. McAnulty JH, Rahimtoola SH, Murphy ES, Kauffman S, Ritzmann LW, Kanarek P
et al. A prospective study of sudden death in ‘high-risk’ bundle-branch block. N
Engl J Med 1978;299:209 –15.
6. Dhingra RC, Wyndham C, Bauernfeind R, Denes P, Wu D, Swiryn S et al. Significance of chronic bifascicular block without apparent organic heart disease. Circulation 1979;60:33 –9.
7. Dhingra RC, Denes P, Wu D, Chuquimia R, Amat-Y-Leon F, Wyndham C et al.
Syncope in patients with chronic bifascicular block: Significance, causative mechanisms, and clinical implications. Ann Intern Med 1974;81:302 –6.
8. Delise P. Aritmie: diagnosi, prognosi e terapia. Casa Editrice Scientifica Internazionale, 2004.
9. Marti-Almor J, Cladellas M, Bazan V, Altaba C, Guijo M, Delclos J et al. Long-term
mortality predictors in patients with chronic bifascicular block. Europace 2009;11:
1201–7.
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