Left bundle branch block without a typical contraction pattern is associated with increased risk of ventricular...

Area of Science:

• Cardiology
• Electrophysiology
• Medical Imaging

Background:

• Cardiac resynchronization therapy (CRT) is effective in reducing ventricular arrhythmias (VA) for heart failure (HF) patients with left bundle branch block (LBBB).
• The efficacy of CRT in non-LBBB patients or those with less defined LBBB is less clear.
• Identifying patients at risk for VA despite meeting conventional LBBB criteria is crucial for optimizing CRT outcomes.

Purpose of the Study:

• To determine if the absence of specific LBBB features, assessed by echocardiography (longitudinal strain) or strict ECG criteria, identifies CRT candidates at increased risk of developing VA.
• To refine patient selection for CRT by identifying subgroups who may not benefit as expected or are at higher risk for arrhythmias.

Main Methods:

• Prospective study of 206 CRT candidates from two centers.
• Pre-CRT assessment included echocardiographic assessment of LBBB contraction pattern using longitudinal strain and ECG categorization based on strict Strauss criteria.
• Primary endpoint was the occurrence of any appropriate antitachycardia pacing or shock therapy within two years post-CRT implantation.

Main Results:

• 45 patients (22%) experienced VA within two years.
• Absence of a typical LBBB contraction pattern on echocardiography was independently associated with a higher risk of VA (HR 1.89).
• Patients meeting neither strict ECG nor echocardiographic LBBB criteria had a 3.3-fold increased risk of VA (HR 3.34).

Conclusions:

• The absence of typical LBBB contraction patterns, identified via echocardiography, is an independent predictor of increased VA risk in CRT candidates.
• Strict ECG criteria for LBBB alone were not independently associated with VA occurrence.
• Combining echocardiographic and strict ECG assessments can better identify CRT candidates at risk for developing ventricular arrhythmias, even within a cohort initially selected for LBBB.