Association between HV interval and electrocardiographic findings in individuals with syncope and left bundle branch block

Funding Acknowledgements

Type of funding sources: None.

Introduction

The occurrence of syncope is associated with increased mortality in patients with left bundle branch block (LBBB). Among syncope risk scores, it is consensual that electrocardiographic (ECG) abnormalities and the presence of underlying cardiac disease are prominent factors. However, there is no further investigation directed towards this population and there is few that could add to clinical judgement in such cases, until electrophysiological study (EPS) is performed. The method’s modest sensitivity limits its practical usage in spite of current literature recommendation. Therefore, identifying those patients more prone to serious events is of clinical significance.

Objectives and methods

This was a cross-sectional study of patients with syncope and LBBB undergoing EP study in a tertiary hospital, which aimed to assess the relation between ECG parameters and prolonged HV interval on EPS.

Results

Ninety-four consecutive patients were eligible for the final analysis. Mean age was 63.1 ± 11.9 years (68.1% male). As for main comorbidities, the prevalence of smoking was 39.3%, hypertension 84%, diabetes mellitus 29.7%, coronary artery disease 28.7% and reduced left ventricle ejection fraction (LVEF) (≤ 40%) 48.9%. In the univariable analysis, LVEF ≤ 40% appeared to be somewhat important but this was not confirmed upon logistic regression. QRS duration ≥ 165 ms (OR 7.79; p = 0.0005) and PR interval ≥ 220 ms (OR 7.10; p = 0.003) were independent predictors for HV interval ≥ 70 ms. For each 10 ms increase in QRS and PR duration, the odds of HV interval ≥ 70 ms enhanced by 39.8% and 27.1%, respectively. For the subgroup presented with such outcome, mean QRS was 170.88 ± 26.81 ms, significantly larger than the patients with HV interval < 70 ms. When combined, QRS ≥ 165 ms and PR interval ≥ 220 ms had an accuracy of 80% to predict an HV interval ≥ 70 ms in the EPS. Other analyzed data were not systematically associated with the evaluated outcome.

Conclusion

In patients with syncope and LBBB, prolonged QRS and PR interval were independent predictors of increased HV interval on EP study. Larger studies are needed to confirm these findings.