Incidence of subclinical atrial fibrillation in a South Asian population

BACKGROUND: South Asians have a lower prevalence of atrial fibrillation (AF) compared with Caucasians despite higher rates of conventional risk factors and a higher incidence of stroke. It is not clear whether South Asians truly experience less AF or whether this is due to underdetection of the arrhythmia. Therefore, we aimed to determine whether South Asian patients with pacemakers have a lower incidence of device-detected subclinical episodes of AF compared with Caucasian controls. METHODS: We performed a retrospective cohort study of South Asian and Caucasian patients who underwent pacemaker implantation between 2006 and 2016. Subclinical AF episodes, detected during subsequent device clinic follow-up visits, were identified and the occurrence of clinical AF, cerebrovascular events, and all-cause mortality was recorded. RESULTS: A total of 5 648 patients underwent pacemaker implantation at the Yorkshire Heart Centre, UK, during the study period. Of these, 169 were South Asian and 72 met the eligibility criteria. The cumulative incidence of subclinical AF was significantly lower in South Asians compared with Caucasians (logrank P = 0.002) with an annual event rate of 6.9% versus 13.9%, and South Asian ethnicity was an independent predictor of a lower incidence of subclinical AF (odds ratio = 0.43; 95% confidence interval = 1.01-5.38). CONCLUSIONS: South Asians with an implanted pacemaker have a lower rate of subclinical AF compared with Caucasians.