Atrial fibrillation status and associations with adverse clinical outcomes in patients hospitalised with COVID-19: a large unselected statewide population-linkage study.

Background: Atrial fibrillation (AF) is common in COVID-19 patients. The impact of AF on major-adverse-cardiovascular-events (MACE defined as all-cause mortality, myocardial infarction, ischemic stroke, cardiac failure or coronary revascularisation), recurrent AF admission and venous thromboembolism in hospitalised COVID-19 patients is unclear.

Methods: Patients admitted with COVID-19 (1-January-2020 to 30-September-2021) were identified from the New South Wales Admitted-Patient-Data-Collection database, stratified by AF status (no-AF vs prior-AF or new-AF during index COVID-19 admission) and followed-up until 31-Mar-2022. Multivariable Cox regression and competing risk analyses were performed to assess the impact of AF on MACE and non-fatal outcomes respectively.

Results: Our cohort comprised 145293 COVID-19 patients (median age 67.4yo; 49.7% males): new-AF, n=5140 (3.5%); prior-AF, n=23204 (16.0%). During a median follow-up of 9-months, prior-AF and new-AF patients had significantly higher MACE events (44.7% vs 36.2% vs 18.0%) and all-cause mortality (36.0% vs 28.7% vs 15.2%) compared to no-AF patients (both logrank P<0.001). After adjusting for age, gender, intensive-care-unit admission, referral source and comorbidities, compared to no-AF, new-AF and prior-AF groups were independently associated with MACE (adjusted hazard ratio[aHR]=1.15, 95% confidence interval[CI]=1.09-1.20; aHR=1.36, 95%CI=1.33-1.40 respectively). Competing risk analyses showed rehospitalisation rates for ischemic stroke, cardiac failure and AF, but not venous thromboembolism, were significantly higher in these patients. Both new-AF and prior-AF patients had higher rehospitalisation rates for ischemic stroke compared to no-AF patients, independent of CHA2DS2VASc.

Conclusions: COVID-19 patients with AF are at high risk of adverse clinical outcomes. Such patients may need increased surveillance and consideration for early anticoagulation.