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Published on: December 11, 2017
Prevalence and prognostic impact of bundle branch block in patients with heart failure: evidence from the CHARM
Nathaniel M Hawkins1, Duolao Wang, John J V McMurray
1Stobhill Hospital, Glasgow, UK. nathawkins@hotmail.com
Insights
Bundle branch block (BBB) predicts worse outcomes in heart failure with reduced ejection fraction. While less common and with a weaker association in heart failure with preserved ejection fraction, BBB still indicates increased cardiovascular risk.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Bundle branch block (BBB) is a known predictor of cardiovascular mortality in heart failure with reduced left ventricular ejection fraction (HFrEF).
- Prognostic implications of BBB in heart failure with preserved ejection fraction (HFpEF) are less understood.
Purpose of the Study:
- To investigate the prognostic significance of BBB in patients with HFpEF compared to HFrEF.
- To assess the association between BBB and cardiovascular outcomes within the CHARM program.
Main Methods:
- Analysis of data from the Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) programme.
- Examined the relative risk of cardiovascular death or HF hospitalization associated with BBB compared to a normal electrocardiogram.
Main Results:
- BBB prevalence was lower in HFpEF (14.4%) versus HFrEF (29.6-30.5%).
- Overall, BBB increased the risk of adverse outcomes (adjusted hazard ratio 1.48).
- In HFrEF, BBB significantly increased risk (adjusted HR 1.72), while the association in HFpEF was not statistically significant in adjusted analysis (HR 1.16).
Conclusions:
- BBB is a strong predictor of adverse outcomes in HFrEF.
- BBB is less frequent and has a more modest predictive effect in HFpEF.
Background:
Bundle branch block (BBB) is a powerful independent predictor of cardiovascular mortality in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). The prognostic implications in HF with preserved systolic function (HF-PSF) are less well understood.
Methods:
The Candesartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) programme randomised 7599 patients with symptomatic HF to receive candesartan or placebo. The primary outcome comprised cardiovascular death or HF hospitalisation. The relative risk conveyed by BBB relative to a normal electrocardiogram was examined.
Results:
The prevalence of BBB was significantly lower in patients with preserved compared with reduced systolic function (CHARM-Preserved 14.4%, Alternative 29.6%, Added 30.5%), p<0.0001. Overall, the adjusted hazard ratio for the primary outcome was 1.48 (95% confidence interval 1.22-1.78), p<0.0001, reflecting increased risk in patients with reduced LVEF (1.72 [1.28-2.31], p=0.0003). The apparently more modest risk among patients with HF-PSF was significant in unadjusted (1.80 [1.37-2.37], p<0.0001) but not adjusted analysis (1.16 [0.88-1.54], p=0.2897). However, no formal statistical difference was observed between the two cohorts, and interpretation is limited by the unknown prevalence of left and right BBB morphologies in each. Comparing BBB presence with absence yielded qualitatively similar results.
Conclusion:
The simple clinical finding of BBB is a powerful independent predictor of worse clinical outcomes in patients with HF and reduced LVEF. It is less frequent, with a more modest predictive effect, in patients with preserved systolic function.
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