Mortality in congestive heart failure complicated by atrial fibrillation

Michael Sosin*, Russell C. Davis and Gregory Y.H. Lip

Haemostasis Thrombosis and Vascular Biology Unit, University Department of Medicine, City Hospital, Birmingham B18 7QH, UK

* Correspondence to: Dr M Sosin, Haemostasis Thrombosis and Vascular Biology Unit, University Department of Medicine, City Hospital, Dudley Road, Birmingham B18 7QH, UK. Tel.: +44-121-554-3801; Fax: +44-121-554-4083
E-mail address: mike_sosin{at}doctors.org.uk

Received 21 November 2002; accepted 7 August 2003

We read with great interest the paper by Baldasseroni et al. who report increased mortality in patients with congestive heart failure (CHF) complicated by atrial fibrillation (AF), left bundle-branch block (LBBB) or both.1This observation is interesting, but probably not surprising, as AF and LBBB are associated with a number of factors which may affect mortality and morbidity in CHF patients.

Many cardiovascular (and cerebrovascular) events associated with CHF and AF have thrombosis as the underlying pathophysiological process. AF is associated with a hypercoagulable state, and an increased risk of thromboembolism compared to sinus rhythm.2CHF fulfils the components of Virchow’s triad for thrombogenesis, and epidemiological data support an association between CHF and thromboembolism3although clinical trials to establish the role of antithrombotic therapy in CHF are still ongoing.4However, a recent Cochrane review suggested that the limited data available would support some role for anticoagulation with warfarin in patients with severe CHF,4particularly in patients with AF. The numbers of patients in this study receiving oral anticoagulants was not reported, and this may be an important factor in mortality in the AF groups (C and D).

Furthermore, the incidence and prevalence of AF increases with age. Indeed, in the study by Balderassoni et al.,1patients in groups C and D (with AF) were older than those in groups A and B (no AF). Age itself brings with it an increase in mortality from vascular events.

Are conduction abnormalities (LBBB) relevant in this? Following myocardial infarction (MI), LBBB is suggestive of extensive MI, and is associated with a greater frequency of wall motion abnormality and a greater degree of left ventricular impairment.5Indeed, in the paper by Baldasseroni et al.,1groups B and D (those with LBBB) had a worse left ventricular ejection fraction than those in groups A and C (those with no LBBB). These factors are associated with increased thrombotic tendency,2which is likely to be important in both sudden and non-sudden death in patients with CHF.

It is interesting that the proportion of patients with ischaemic heart disease (IHD) was found to be higher (53.3%) in group A (no LBBB or AF) than in the groups of patients with LBBB, AF or both (33.3–35.4%). This suggests that LBBB and AF are more commonly found in association with non-ischaemic cardiomyopathy, and secondly, patients with non-ischaemic cardiomyopathy have a worse prognosis than their counterparts with IHD. The aetiology of CHF may therefore be a confounding factor in this analysis, and it would be interesting to see the effect of AF and LBBB analysed separately for the ischaemic and non-ischaemic subgroups of patients.

Finally, it is important to note that although a high proportion of all patient groups were receiving angiotensin-converting enzyme inhibitors (79.6–87.6%), the proportion of patients receiving beta-blockers was low throughout, and substantially lower in the groups with LBBB. The overall low use of beta-blockers may reflect the year of the study (1995), but the variation between groups is less easy to explain—it may reflect reluctance to prescribe beta blockers to patients with lower ejection fractions. However, as beta blockade has been shown to improve prognosis in heart failure,6this variation may substantially affect the mortality observed in the study.

Although LBBB and AF are undoubtedly markers of high risk in patients with CHF, due to their association with a prothrombotic state, there seems little evidence to base treatment decisions (other than anticoagulation) on the presence or absence of these factors.

References

  1. Baldasseroni S, De Biase L, Fresco C et al. Cumulative effect of complete left bundle-branch block and chronic atrial fibrillation on 1-year mortality and hospitalisation in patients with congestive heart failure. Eur Heart J. 2002;23:1692–1698.[Abstract/Free Full Text]
  2. Lip GYH. Does atrial fibrillation confer a hypercoagulable state? Lancet. 1995;346:1313–1314.[Medline]
  3. Chin BS, Lip GYH. Thromboembolism in heart failure. Cardiovascular Reviews and Reports (In press)..
  4. Lip GYH, Gibbs CR. Anticoagulation for heart failure in sinus rhythm (Cochrane Review). In: The Cochrane Library, issue 4, 2001.Oxford: Update software..
  5. Sugiura T, Yamasaki F, Hatada K et al. Correlates of bundle-branch block in patients undergoing primary angioplasty for acute myocardial infarction. Clin Cardiol. 2001;24:770–774.[Medline]
  6. CIBIS-II Investigators and Committees. The Cardiac Insufficiency Bisoprolol Study II. Lancet. 1999;353:9–13.[Medline]




This Article
Full Text (PDF)
Alert me when this article is cited
Alert me if a correction is posted
Services
Email this article to a friend
Similar articles in this journal
Similar articles in ISI Web of Science
Similar articles in PubMed
Alert me to new issues of the journal
Add to My Personal Archive
Download to citation manager
Request Permissions
Google Scholar
Articles by Sosin, M.
Articles by Lip, G. Y.H.
PubMed
PubMed Citation
Articles by Sosin, M.
Articles by Lip, G. Y.H.