Is there an increased prevalence of cardiovascular disease with the presence of left bundle branch block (LBBB)?

From the Guidelines

Yes, there is an increased prevalence of cardiovascular disease associated with left bundle branch block (LBBB). LBBB is often a marker of underlying structural heart disease rather than a primary electrical abnormality. Patients with LBBB have a higher likelihood of having coronary artery disease, hypertension, cardiomyopathy, valvular heart disease, or heart failure compared to those without LBBB.

Key Points

• The presence of LBBB on an electrocardiogram (ECG) in asymptomatic individuals should prompt consideration for further cardiac evaluation, as it may represent the first sign of otherwise undetected cardiovascular disease 1.
• This association exists because LBBB typically develops when there is damage to the conduction system from processes that affect the left ventricle or interventricular septum.
• The mechanical dyssynchrony caused by LBBB can also lead to progressive left ventricular dysfunction over time, potentially worsening heart failure in those with pre-existing cardiac disease.
• A study found that LBBB was associated with significantly worse mortality (HR: 1.17; 95% CI: 1.00–1.36) and a decrease in LVEF to #35% (HR: 1.34; 95% CI: 1.09–1.63) in patients with an LVEF of 36% to 50% 1.

Recommendations

• When LBBB is discovered, especially in patients with cardiovascular risk factors, a comprehensive cardiac assessment is often warranted to identify any underlying cardiovascular pathology.
• This assessment may include echocardiography, cardiac MRI, or other imaging tests to evaluate left ventricular function and identify potential underlying structural heart disease 1.
• Patients with LBBB and symptoms of heart failure may benefit from cardiac resynchronization therapy (CRT) to improve symptoms and reduce mortality 1.

From the Research

Association between Left Bundle Branch Block and Cardiovascular Disease

• The presence of left bundle branch block (LBBB) has been associated with an increased risk of cardiovascular morbidity and mortality 2, 3, 4, 5, 6.
• Studies have shown that LBBB is a predictor of poor left ventricular function in coronary artery disease 6.
• The prevalence of LBBB varies across different populations, ranging from 2.5% in a community-based cohort study 2 to 16% in patients with acute heart failure syndrome 5.
• LBBB has been linked to an increased risk of congestive heart failure, cardiovascular death, and sudden cardiac death 2, 3, 4, 5.

Clinical Significance of Left Bundle Branch Block

• LBBB is associated with a higher incidence of congestive heart failure and cardiovascular death, even in the absence of clinically detectable heart disease 2.
• The presence of LBBB is an independent predictor of death or heart failure hospitalization in patients with permanent pacemakers 4.
• LBBB is also a predictor of poor long-term outcome in patients surviving a severe episode of de novo acute heart failure or acute heart failure complicating a mild chronic heart failure 5.
• The severity of coronary artery disease and left ventricular dysfunction is greater in patients with LBBB compared to those without LBBB 6.

Prognostic Implications of Left Bundle Branch Block

• LBBB is a significant predictor of cardiovascular mortality and heart failure, and its presence should be considered when assessing a patient's risk profile 2, 3, 4, 5.
• The detection of LBBB may warrant further diagnostic testing or earlier treatment to decrease cardiovascular morbidity or mortality 2.
• The prognostic significance of LBBB highlights the importance of careful evaluation and management of patients with this condition 4, 5, 6.