1. Introduction
The global pandemic caused by coronavirus disease 2019 (COVID-19) continues to evolve and exerts tremendous strain on healthcare systems. Pathomechanisms differentiating patients at high risk for adverse outcomes from those displaying minor symptoms and a mild course of disease are insufficiently understood. Cardiovascular involvement and myocardial injury are commonly observed and associated prognostic implications have been suggested by early reports [1,2,3,4]. Impairment of ventricular function and inflammatory myocardial processes have been detected in COVID-19 patients [5,6]. However, evidence regarding prevalence and prognostic effects of cardiac arrhythmias in COVID-19 is sparse and mainly limited to single center observations. Early studies among the first patient cohorts analyzed in China reported an incidence of cardiac arrhythmia of 17%, with rates of up to 44% in patients admitted to ICU [7]. However, there was no information on the respective types of arrhythmia diagnosed. Another monocentric study from Pennsylvania reported similar rates of arrhythmia events during hospitalization for COVID-19, in particular in patients treated in an intensive care setting. AF was identified as the most common arrhythmic event [8]. In a cohort of 30 patients from Italy, a possible association of cardiac arrhythmias and increased inflammatory markers as well as mortality in COVID-19 was pointed out, however, with limited reliability of results due to the small sample size [9]. Insight into the role of arrhythmias in COVID-19 is of particular importance as widely used pharmacological therapies attempting to mitigate the course of disease may be associated with proarrhythmic effects [10]. This study aims to systematically investigate the prevalence of cardiac arrhythmias in patients hospitalized for COVID-19 at multiple centers, to identify risk factors for the occurrence of cardiac arrhythmias, and to assess their role regarding clinical course and patient prognosis.