There have been many studies that have been conducted so far in order to unravel the systematic relationship between hydroxychloroquine use and the new-onset atrial fibrillation. This was mostly studied in patients who were already suffering from systematic lupus erythematosus. It was revealed that a retrospective cohort of adult SLE patients from Dec 1, 2014 and May 30, 2017 was specifically conducted where the patients were categorized in various categories of either being HCQ users or the non-users of the same drug. The primary outcome of the incident was that in the population of 4500 patients, nearly 75 percent were the ones who had already consumed HCQ while the remaining proportion of the population was non-existent. Results remained significant and hence,  it was discovered that the use of HCQ helped in an approximate 88 percent decrease in the risk of incidents of atrial fibrillation in SLE patients.

Ref art: https://onlinelibrary.wiley.com/doi/abs/10.1002/acr.24494