Objective The South Asian population has a lower burden of arrhythmia compared with Caucasians despite a higher prevalence of traditional cardiovascular risk factors. We aimed to determine whether this was due to differences in the electrophysiological properties of the South Asian heart.
Methods We performed a retrospective cohort study of South Asian and Caucasian patients who underwent an electrophysiology study for supraventricular tachycardia between 2005 and 2017. Surface ECG, intracardiac ECG and intracardiac conduction intervals were measured and a comparison between the two ethnic cohorts was performed.
Results A total of 5908 patients underwent an electrophysiology study at the Yorkshire Heart Centre, UK, during the study period. Of these 262 were South Asian and 113 met the eligibility criteria. South Asians had a significantly higher resting heart rate (p=0.024), shorter QRS duration (p=0.012) and a shorter atrioventricular (AV; p=0.001)) and ventriculoatrial (VA; p=0.013) effective refractory period (ERP). There was no difference in atrial or ventricular ERP. On linear regression analysis, South Asian ethnicity was independently predictive of a higher resting heart rate, narrower QRS and shorter AV-ERP and VA-ERP.
Conclusions South Asians have significant differences in their resting heart rate, QRS duration and AV nodal function compared with Caucasians. These differences may reflect variations in autonomic function and may also be influenced by genetic factors. Electrophysiological differences such as these may help to explain why South Asians have a lower burden of arrhythmia.
- atrial fibrillation
- intracardiac electrogram
- intracardiac conduction intervals
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Contributors JO'N was involved in trial design, data acquisition, data analysis and drafting of the manuscript. MHT was involved in trial concept, data interpretation and critical revision of the manuscript.
Funding JO’N has received a fellowship from Abbott. MHT has received research/travelgrants from Abbott, Biosense Webster, Medtronic and Boehringer Ingelheim.
Competing interests None declared.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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