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.

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. [ABSTRACT FROM AUTHOR]