His-bundle pacing versus cardiac resynchronisation therapy: Effect on ECG parameters of repolarization.

INTRODUCTION

Cardiac resynchronization therapy (CRT) by biventricular pacing (BiV) may worsen indices of ventricular repolarization. The impact of His bundle pacing (HBP) on repolarization is not well studied in patients with left ventricular systolic dysfunction. The aim of the study is to compare the repolarization parameters in ECG between these two pacing modalities.

METHODS

Baseline and post implant parameters of 20 patients who had undergone HBP were compared with 18 patients who underwent CRT (BiV) implantation. Repolarization parameters were monitored before implantation, within 24  hours and after 6 weeks of implantation. Patients were followed up till 6 months with clinical and echocardiographic parameters.

RESULT

Baseline clinical, electrocardiographic and echocardiographic parameters were similar in both groups. Significant differences were noted in QT T and T/QT between HBP and CRT groups both on immediate post implant and after 6 weeks of implantation. Compared to pre-implantation,significant shortening of T and T/QT was observed immediately (90.54 ± 24.35 vs 69.62 ± 12.92, p < 0.05 and 0.20 ± 0.05 vs 0.15 ± 0.03, p < 0.05) and after 6 weeks (90.54 ± 24.35 vs 66.08 ± 14.95, p < 0.05 and 0.20 ± 0.05 vs 0.15 ± 0.02, p < 0.05) in HBP implant (group A). However, these changes were not present in CRT cohort (group B). During a follow up of 6 months, NYHA class and LV function between two groups remain comparable.

CONCLUSION

HBP is associated with significant reduction of T and T/QT compared to CRT. Further evaluation is needed to determine whether this improvement in indices of repolarization is associated with reduction in clinical arrhythmic events or not.