New-onset atrial fibrillation: incidence, characteristics, and related events following a national COVID-19 lockdown of 5.6 million people

Abstract

Aim: To determine the incidence, patient characteristics, and related events associated with new-onset atrial fibrillation (AF) during a national COVID-19 lockdown.

Methods and results: Using nationwide Danish registries, we included all patients, aged 18-90 years, receiving a new-onset AF diagnosis during the first 3 months of 2019 and 2020. The main comparison was between patients diagnosed during lockdown (12 March 12-1 April 2020) and patients diagnosed in the corresponding period 1 year previously. We found a lower incidence of new-onset AF during the 3 weeks of lockdown compared with the corresponding weeks in 2019 [incidence rate ratios with 95% confidence intervals (CIs) for the 3 weeks: 0.66 (0.56-0.78), 0.53 (0.45-0.64), and 0.41 (0.34-0.50)]. There was a 47% drop in total numbers (562 vs. 1053). Patients diagnosed during lockdown were younger and with a lower CHA2DS2-VASc score, while history of cancer, heart failure, and vascular disease were more prevalent. During lockdown, 30 (5.3%) patients with new-onset AF suffered an ischaemic stroke and 15 (2.7%) died, compared with 45 (4.3%) and 14 (1.3%) patients during the corresponding 2019 period, respectively. The adjusted odds ratio of a related event (ischaemic stroke or all-cause death) during lock-down compared with the corresponding weeks was 1.41 (95% CI 0.93-2.12).

Conclusions: Following a national lockdown in Denmark, a 47% drop in registered new-onset AF cases was observed. In the event of prolonged or subsequent lockdowns, the risk of undiagnosed AF patients developing complications could potentially translate into poorer outcomes in patients with AF during the COVID-19 pandemic.

Keywords: Atrial fibrillation; COVID-19 pandemic; Collateral damage; National lockdown.

Graphical Abstract

Take home figure

Incidence of new-onset atrial fibrillation and related ischaemic stroke and death during the first 3 months of 2019 and 2020. (A and B) Incidence rates of new-onset atrial fibrillation (AF) within the first 3 months of 2019 and 2020 including hospitalizations. Incidence rates per 1000 person-years are read on the left y-axis. The black line shows the proportion of AF diagnoses with a related event (ischaemic stroke or all-cause death within 7 days of AF diagnosis); the dotted line shows the proportion among hospitalized patients with new-onset AF. Proportions in % are read on the right y-axis.

Figure 1

Weekly incidence rate ratios comparing the first 3 months of 2020 and 2019. IRR, incidence rate ratio; CI, confidence interval. As of 1 January 2019, 5.26 million persons contributed to the analysis. As of 2 January 2020, 5.30 million persons contributed to the analysis. Period refers to the exact dates of 2020 and 2019 which are compared. The 1-day gap the first nine periods was due to 2020 being a leap year. The grey area indicates lockdown compared with corresponding weeks. Incidence rate ratios are unadjusted and were calculated using a Poisson regression.

Figure 2

Odds ratios of related stroke or all cause death to atrial fibrillation diagnosis. CI = confidence intervals. A multivariable logistic regression, including the variables shown, was fitted to calculate odds of a related event comparing patients diagnosed with atrial fibrillation during lockdown with the patients diagnosed during the corresponding weeks in 2019. Scores for gender and age have been removed from the CHA₂DS₂-VASc score, since those factors are independent variables in the model.