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Background: COVID-19 is a multiorgan disease. We previously identified COVID-19 as a risk factor for myocardial infarction, stroke (1), venous thromboembolism and bleeding (2). Less evidence exists on the risk of arrhythmias after COVID-19. Previous studies included mainly hospitalized patients with severe COVID-19, and there are no nationwide studies published.

Purpose: The aim of this study was to estimate the risk of atrial tachycardias (atrial fibrillation and atrial flutter) following COVID-19, including all individuals tested positive for SARS-CoV-2 in Sweden, regardless of disease severity.

Method: COVID-19 has been a notifiable disease in Sweden. All individuals in Sweden who were tested positive for SARS-CoV-2 between February 1, 2020 and May 25, 2021 were included in the study. We identified four control individuals for each COVID-19 individual matched on age, sex, and county of residence. Using Personal Identification Numbers, we cross-linked data from national registries: COVID-19 registry; Inpatient and Outpatient Registry; Cause of Death Registry; Prescribed Pharmaceutical Registry and Intensive Care Registry. Outcomes are cardiovascular events, defined using ICD-10 diagnosis codes for atrial fibrillation and atrial flutter in the registries. We performed a ‘’first-ever event’’ analysis, i.e., we excluded individuals with events before the study period. The self-controlled case series (SCCS) method was used to determine the incidence rate ratio (IRR) of a first atrial tachycardia during the risk periods 1-7, 8-14, 15-30, 31-60, 61-90, and 91-180 days after COVID-19. In the matched cohort study (MCS), Poisson regression was performed to calculate the risk ratio (RR) of a first arrhythmia event in the risk period 1-30 days following COVID-19, after adjusting for the effect of confounders, such as cardiac disease, treatment with antiarrhythmics, comorbidities and vaccination status.

Results: 1 057 174 cases and 4 074 844 controls were included in the study. In the SCCS, the risk of first atrial tachycardia was significantly increased up to 60 days following COVID-19. Specifically, during days 1-7 and 8-14 post-COVID-19 the IRRs were approximately 12 and 10 respectively. Similarly, in the MCS the RR for the first atrial tachycardia during day 1-30 post-COVID-19 was approximately 11. The risks were higher in patients with more severe COVID-19; and during the first pandemic wave compared to the second and third wave.

Conclusions: This study suggests that COVID-19 is a risk factor for atrial tachycardias, based on information obtained on all people who tested positive for SARS-CoV-2 in Sweden, regardless of disease severity. These results could impact recommendations on diagnostic and prophylactic strategies against atrial tachycardias after COVID-19. The importance of preventive strategies, such as risk factor control; vaccination to prevent severe COVID-19; and early review of high-risk individuals after COVID-19, is indicated.