Abstract
BackgroundSouth Asians have a low prevalence of atrial fibrillation (AF) in comparison with White Europeans despite a higher burden of hypertension, diabetes mellitus and coronary artery disease. The reason for this disparity is unclear but may relate to electrophysiological or structural differences within the atria or variations in autonomic function. We aimed to assess these areas using a range of non-invasive cardiac investigations.MethodsA prospective cohort study was performed on 200 South Asian and 200 Caucasian healthy volunteers aged 18–40 years. All subjects underwent electrocardiography (ECG), echocardiography and anthropometric measurements. Eighty subjects in each cohort underwent 24 hour ambulatory ECG and fifty subjects in each cohort underwent exercise testing.ResultsCompared with White Europeans, South Asians were of a smaller height with lower lean body mass and smaller left atrial size. They had reduced P wave dispersion and P wave terminal force in lead V1. South Asians had a lower burden of supraventricular ectopy. They had a higher mean heart rate and South Asian males had lower heart rate variability, suggestive of sympathetic predominance. Exercise capacity was lower in South Asians.ConclusionsSouth Asians have differences in left atrial size, P wave indices, burden of supraventricular ectopy, heart rate, heart rate variability and anthropometric measurements. These differences may relate to variations in atrial morphology, atrial electrophysiology and autonomic function and might help to explain why South Asians are less susceptible to developing AF.
Highlights
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia[1] with an estimated prevalence of around 3% in adults aged 20 years or older[2]
Compared with White Europeans, South Asians were of a smaller height with lower lean body mass and smaller left atrial size
South Asians had a lower burden of supraventricular ectopy
Summary
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia[1] with an estimated prevalence of around 3% in adults aged 20 years or older[2]. Risk factors for the development of the arrhythmia include hypertension, diabetes mellitus and coronary artery disease[3]. These conditions are prevalent amongst the South Asian population[4,5], a diverse ethnic group which makes up around a fifth of the world’s population, is the largest minority group in the United Kingdom[6] and represents one of the fastest growing immigrant populations in North America[7]. Alterations in autonomic tone are recognised as playing an important role in the genesis of AF through the creation of ectopic foci and the effects on atrial refractoriness[10]
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