Value of q waves in lateral and left precordial leads in patients with left bundle branch block to predict the response to cardiac resynchronization therapy

Abstract Background The cardiac resynchronization therapy (CRT) non‐response rate can reach 30% in heart failure (HF) patients with left bundle branch block (LBBB). This study aimed to evaluate the value of baseline q waves in leads I, V5, or V6 in predicting response to CRT in patients with HF and LBBB. Methods Patients with HF (left ventricular ejection fraction ≤35%) and LBBB receiving CRT implantation were retrospectively enrolled. Baseline characteristics and electrocardiogram parameters, including lateral and left precordial q waves were evaluated. Non‐response to CRT was defined as the improvement of left ventricular ejection fraction (LVEF) < 5% at a 6‐month follow‐up. Results A total of 132 patients (mean age 63.0 ± 10.4 years, 94 [71.2%] male) were included. Among them, 32 patients with q waves in leads I, V5, or V6 were classified into the qLBBB (+) group, and the rest without q waves in these leads were defined as the qLBBB (‐) group. The CRT non‐response rate in the qLBBB (+) group was markedly higher than that in the qLBBB (‐) group (68.8% vs. 33.3%, p < .001). Multivariable logistic regression analysis revealed that the presence of baseline q waves in leads I, V5, or V6 remained significantly associated with a higher rate of CRT non‐response in patients with HF and LBBB (odds ratio: 4.8, 95% confidence interval: 1.5–15.0, p = .007). Conclusion Any q wave in leads I, V5, or V6 was an independent predictive factor for CRT non‐response in patients with HF and LBBB.