Lead-Site Myocardial Scar Predicts Echocardiographic Response to Left Bundle Branch Area Pacing

As a novel technique, left bundle branch area pacing (LBBAP) can achieve excellent resynchronization in heart failure (HF) patients with left bundle branch block (LBBB). This study used cardiovascular magnetic resonance (CMR) to evaluate the scar burden at the lead deployment site and its ability to predict the echocardiographic response.

Eighty-seven HF patients with LBBB and a left ventricular ejection fraction (LVEF)≤ 35% who underwent CMR examination and successful LBBAP implantation were retrospectively enrolled. Based on the results of the 6-month echocardiographic assessment after LBBAP, a response was defined as a reduction in the left ventricular end-systolic volume (LVESV) of ≥ 15%, and a super-response was defined as an improvement in the LVEF of ≥ 20% or greater than 50%. The myocardial scar, including global, septum, free wall, lateral and scar around lead deployment sites, was assessed by CMR. LBBAP achieved an 86.2% response rate and a 50.6% super-response rate. Compared with other LGE parameters, a superior negative linear correlation was found between the scar load around lead deployment site and LVESV reduction and improvement in LVEF, indicating that for every 1% increase in the scar burden of the lead deployment site, the delta LVESV decreased by 0.94%, and the delta LVEF decreased by 0.43%. The scar around lead deployment site can strongly predict responders and super-responders [area under the receiver operating characteristic curve (AUC: 0.87 and 0.76), respectively]. In patients with scars around deployment sites > 12.3% (cut-off values based on the Youden's index), the rates of response and super-response decreased substantially to 56.0% and 16.0%, respectively.

The scar burden around lead deployment site as assessed by CMR, which is commonly located around the mid anteroseptum, can predict the echocardiographic response. Assessment of myocardial late gadolinium enhancement in the lead deployment site is recommended.