What is the treatment for Left Bundle Branch Block (LBBB)?

From the Guidelines

Left bundle branch block (LBBB) treatment primarily involves identifying and treating underlying cardiac conditions, with cardiac resynchronization therapy (CRT) being beneficial for patients with LBBB and heart failure with reduced ejection fraction, especially when the QRS duration is ≥150 ms, as shown in the 2015 ESC guidelines 1. The primary approach to treating LBBB is to identify and treat any underlying cardiac conditions. If LBBB is newly diagnosed, a thorough cardiac evaluation is recommended, including echocardiography to assess for structural heart disease and cardiac function.

• For patients with LBBB and heart failure with reduced ejection fraction, CRT with a biventricular pacemaker may be beneficial, especially when the QRS duration is ≥150 ms 1.
• Medications are directed at treating the underlying heart condition rather than the LBBB itself - this might include beta-blockers, ACE inhibitors, ARBs, or SGLT2 inhibitors for heart failure.
• For patients with LBBB and symptomatic bradycardia, a permanent pacemaker may be necessary.
• Regular cardiac follow-up is important to monitor for progression of conduction disease or development of heart block. LBBB is significant because it indicates electrical conduction abnormality in the heart and can worsen cardiac efficiency by causing dyssynchronous ventricular contraction, potentially contributing to heart failure symptoms even with preserved ejection fraction. The 2015 ESC guidelines provide strong evidence favoring the use of CRT in patients with LBBB and heart failure with reduced ejection fraction, especially in those with a QRS duration ≥150 ms 1.
• The guidelines also suggest that CRT may be beneficial in patients with non-LBBB QRS morphology with a QRS ≥160 ms, but this requires further exploration.
• The success of CRT in patients with atrial fibrillation is determined by the degree of biventricular pacing, which can be achieved by means of AV junction ablation in many patients. Overall, the treatment of LBBB should be individualized based on the underlying cardiac condition and the presence of symptoms or heart failure.

From the Research

Treatment Options for Left Bundle Branch Block (LBBB)

• Cardiac resynchronization therapy (CRT) is a treatment option for patients with heart failure and LBBB, particularly those with reduced ejection fraction 2, 3, 4.
• Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT, with studies showing significant improvements in clinical and echocardiographic outcomes 3, 5.
• Lead placement via the coronary sinus is the mainstay approach of CRT, but other options such as physiological pacing are being explored 2.
• Left bundle branch pacing (LBBP) has also been shown to be effective and safe in heart failure patients with LBBB, with improvements in QRS duration, left ventricular ejection fraction, and clinical outcomes 5.

Patient Selection and Response to Treatment

• Patients with true LBBB morphology may have a better clinical and instrumental response to CRT, with studies showing a higher event-free survival rate and greater increase in left ventricular ejection fraction 6.
• Baseline LBBB and left ventricular end-diastolic diameter have been identified as independent predictors of echocardiographic response to LBBAP 3.
• The success rate of LBBP has been reported to be around 93.2%, with significant improvements in clinical and echocardiographic outcomes 5.

Alternative Therapies

• Baroreflex activation therapy (BAT) and cardiac contractility modulation (CCM) may be considered as alternative electrical therapies for patients with heart failure and reduced ejection fraction who are not candidates for CRT 4.
• These therapies aim to modulate vegetative dysregulation and improve contractility, functional capacity, and symptoms, but more data are needed to establish their mortality benefits 4.