Left bundle branch block natural history, complications and prognosis
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Differentiating Left Bundle Branch Block from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]
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Complications
- Pulmonary arterial line placement [1] in a patient with LBBB can result in a complete heart block if the right bundle branch is traumatized during the process.
- Progression to higher degree AV block: It was shown in the Swedish study that the risk of progression was more pronounced in left block than in right bundle branch block.
- Bradycardia
- Delay in the diagnosis of MI: Presence of LBBB can delay the diagnosis of an acute MI.
- Sudden cardiac death is a potential complication when associated with a heart attack.
Prognosis
Age Under 50 Years
In asymptomatic patients under the age of 50, LBBB does not appear to be associated with an adverse prognosis.
Age Over 50 Years
It is notable that when LBBB is the presenting feature of an acute MI, the patient will not present with any chest pain half the time. Unfortunately, patients whose only manifestation of an acute MI is a left bundle branch block are less frequently treated with reperfusion therapy, and they have a worse prognosis.[2] A large Swedish study in men more than 45 years old with LBBB who were followed-up for over 25 years, showed both a much higher risk for developing high degree atrioventricular block and a markedly higher hazard ratio for all-cause mortality than individuals with right bundle branch block.[3]
Several clinical studies have shown that LBBB is associated with a grave prognosis in the presence of the following:
- Coronary artery disease: In patients with known or suspected CAD, LBBB is an independent predictor of all-cause mortality. As compared with diabetics without LBBB and patients with isolated LBBB, patients with LBBB and type II diabetes have more severe and extensive CAD and advanced LV dysfunction.
- Acute MI: Presence of LBBB in the setting of an acute MI can delay and complicate the diagnosis. Both short-term and long-term mortality have been shown to be higher in this association.
- Heart failure: LBBB results in left ventricular dys-synchrony, which compromises the left ventricular function leading to heart failure. Studies have shown LBBB as an independent risk factor for an increase in all-cause mortality and sudden death at one year. These patients could be treated with cardiac resychronization therapy with biventricular pacing.
Exercise-induced LBBB is a transient finding seen in approximately 0.5% of patients undergoing an exercise stress test. In one study of 17,277 exercise stress tests it was found that all-cause mortality and major cardiac events were significantly higher in patients with exercise-induced LBBB.[4]
References
- ↑ Morris D, Mulvihill D, Lew WY (1987). "Risk of developing complete heart block during bedside pulmonary artery catheterization in patients with left bundle-branch block". Archives of Internal Medicine. 147 (11): 2005–10. PMID 3675104. Retrieved 2012-10-17. Unknown parameter
|month=ignored (help) - ↑ Shlipak M, Go A, Frederick P, Malmgren J, Barron H, Canto J. Treatment and outcomes of left bundle-branch block patients with myocardial infarction who present without chest pain. J Am Coll Cardiol. 2000;36(3):706-712.
- ↑ Eriksson P, Wilhelmsen L, Rosengren A (2005). "Bundle-branch block in middle-aged men: risk of complications and death over 28 years. The Primary Prevention Study in Göteborg, Sweden". European Heart Journal. 26 (21): 2300–6. doi:10.1093/eurheartj/ehi580. PMID 16214833. Unknown parameter
|month=ignored (help) - ↑ Stein R, Ho M, Oliveira CM; et al. (2011). "Exercise-induced left bundle branch block: prevalence and prognosis". Arquivos Brasileiros De Cardiologia. 97 (1): 26–32. PMID 21552647. Unknown parameter
|month=ignored (help)