Background: After its approval in December 2020, COVID-19 vaccines have reduced the risk of severe illness and death from infections with COVID-19. Although the vaccines are normally well tolerated, temporary flu-like symptoms like fever are common in the first days after vaccination. Furthermore, rare cases of vaccine-associated myocarditis have been observed in the first weeks after vaccination. It is unclear whether COVID-19 vaccines could be a potential trigger for arrhythmias, especially in patients who are highly vulnerable to arrhythmias like patients with an implantable cardioverter defibrillator. The current study investigated the change in the arrhythmia burden after COVID-19 vaccinations in ICD patients with remote patient monitoring. 

Methods: Data were obtained from a local ICD registry. 84 Patients who received ICD implantation at our department and had remote patient monitoring were included. The time interval of 28 days before and after each COVID-19 vaccination was investigated. Only COVID-19 vaccinations that had no overlap with a time interval of previous COVID-19 vaccination were included in the analysis. The IEGM of each arrhythmia episode was evaluated by a physician. The number of patients and the total amount of arrhythmias and appropriate ICD therapy before and after COVID-19 vaccinations were analyzed. 

Results: In 84 ICD patients with remote patient monitoring 171 vaccinations against COVID-19 were analyzed. Data from the first (n=67), the second (n=17), the third (n=66) and the fourth (n=21) vaccination were evaluated. The number of second vaccinations was lower because in many cases there was an overlap with the time interval after the first vaccination, which was an exclusion criterion. 146 patients received a vaccine based on mRNA technology and 25 patients got a vaccine based on viral vector technology. 58 patients had any kind of arrhythmia 28 days before the vaccination and 57 patients had any kind of arrhythmia 28 days after the vaccination (p=n.s.). Regarding the number of patients, no significant difference could be found looking at the different types of arrhythmias. Analyzing the number of arrhythmias, there were significantly more arrhythmias in the 28 days before the vaccination (mean M=16.73, standard deviation SD=111.62) than in the 28 days after the vaccination (M=14.57, SD=110.10) (p=0.03). This difference was mainly driven by a non-significant trend towards more atrial arrhythmias in the time interval before the vaccination (before vaccination M=4.16, SD=39.78; after vaccination M=2.06, SD 10.87; p=n.s.). No differences were found regarding the number of ventricular arrhythmias before and after the vaccination (p=n.s.). 6 patients before and 7 patients after vaccination received appropriate ICD therapy to treat ventricular arrhythmias (p=n.s.). No cases of myocarditis occurred during the analyzed time interval after vaccination. 

Conclusion: In ICD patients, which are highly vulnerable to arrhythmias, the COVID-19 vaccination did not lead to an increase in arrhythmias and ICD therapies. The amount of all arrhythmias was even lower before than after the vaccination, which might be a result of a change in the patient's behavior, e.g. reduced physical activity or reduced alcohol consumption, during the days after the vaccine was administered. In sum, COVID-19 vaccination was no trigger for arrhythmias in ICD patients.