Determining whether LV filling time contributes to HF symptoms in different widths of QRS in LBBB patients: a clinical study

Objectives: Accurate assessment of left ventricular (LV) function is essential for managing patients with left bundle branch block (LBBB). This study aimed to evaluate the relationship between LV systolic function, left ventricular diastolic filling time (LVFT), QRS duration, and heart failure symptoms in patients with LBBB. Methods: This study was conducted between June 2021 and June 2022. Patients with LBBB and sinus rhythm who were referred to the echocardiography department were included in the study. All the patients underwent electrocardiogram-gated echocardiography using the same machine. In this study, the LVFT value was measured in absolute terms and as a ratio to the R-R interval (LVFT/RR). Results: A total of sixty-five patients were included, forty-two (64.6%) were women, and the mean age was 60.71 ± 8.72. We performed three one-way ANOVA tests that showed that LV filling time/RR ratio, QRS duration, and ejection fraction were significantly different between heart failure classes (p=0.008, p=0.001, and p<0.001, respectively). A weak correlation was observed between LVEF and LVFT/RR (r= 0.349, p=0.004). Additionally, QRS duration was negatively correlated with LVEF (r = -0.395, p=0.004) and LVFT/RR (r = -0.350, p=0.004), although these correlations were weak. Conclusion: We showed that LVFT/RR ratio differed significantly between HF functional classes and was lower in patients with more severe HF symptoms. Additionally, QRS duration was negatively correlated with LVEF and LVFT/RR, and patients with more severe HF symptoms had longer QRS durations.