Lead one ratio in left bundle branch block predicts poor cardiac resynchronization therapy response

Area of Science:

• Cardiology
• Electrophysiology
• Medical Diagnostics

Background:

• A low electrocardiogram (ECG) lead one ratio (LOR) is linked to reduced left ventricular ejection fraction (LVEF) and poorer outcomes in left bundle branch block (LBBB).
• The effect of LOR on cardiac resynchronization therapy (CRT) outcomes in LBBB patients remains unclear.

Purpose of the Study:

• To investigate the association between baseline ECG LOR and clinical outcomes following CRT implantation in LBBB patients.
• To evaluate the impact of LOR on echocardiographic changes, specifically LVEF and LV volumes, after CRT.

Main Methods:

• A cohort of 496 consecutive CRT-defibrillator recipients with LBBB was analyzed.
• Time to heart transplant, left ventricular assist device (LVAD) implantation, or death was compared between LOR groups (<12 vs. ≥12) using Cox-proportional hazard models.
• Changes in LVEF and LV volumes post-CRT were assessed based on LOR.

Main Results:

• A baseline LOR <12 was associated with a 1.69-fold increased risk of heart transplant, LVAD, or death (adjusted HR: 1.69; P=.01).
• Patients with LOR <12 showed less reduction in LV end-diastolic volume (-4% vs. -13%; P=.04) and LV end-systolic volume (-9% vs. -22%; P=.03) after CRT.
• In patients with QRS duration ≥150 ms, LOR <12 significantly increased the risk of adverse events (adjusted HR: 2.01; P=.008).

Conclusions:

• A low baseline ECG LOR (<12) is a predictor of worse outcomes after CRT in LBBB patients.
• The LOR may be particularly useful in identifying high-risk patients with a QRS duration ≥150 ms who may not benefit optimally from CRT.
• This ECG marker could aid in risk stratification for patients undergoing CRT implantation.