Transient but recurrent complete heart block in a patient after COVID-19 vaccination - A case report.

Introduction: Cardiovascular disorders have been extensively reported during COVID-19 illness, including arrhythmias such as atrioventricular conduction disturbances. To date, one case of transient heart block has been reported after COVID-19 vaccine. Case presentation: A 73 years-old woman presented with shortness of breath and fatigue 2 weeks after receiving her second dose of BNT162b2 SARS-CoV-2 mRNA vaccine. ECG showed complete AV block with normal narrow QRS complexes. Chronic treatment with Bisoprolol for hypertension was stopped but complete AV block persisted 48 hours thereafter. Therefore, a permanent pacemaker was implanted. Three months later, pacemaker follow-up revealed no ventricular stimulation, suggesting complete recovery of AV conduction, even after resumption of bisoprolol. Five months after the second dose, she received a third dose of the same vaccine. Three weeks later, she once again complained of dyspnea on exertion. ECG showed sinus rhythm with permanent ventricular stimulation. After device inhibition, complete AV block was confirmed and, 2 weeks later, conduction was restored once more. Clinical discussion: It is known that vaccines can induce AV conduction disturbances, mostly reversible. The underlying mechanisms leading to high-degree AV block remain unclear and are probably multiple. Although being exceptional after COVID-19 vaccine, our case illustrates the fact that the latter can induce such a disturbance which may be transient and recurrent even in the absence of underlying conduction disorder. Conclusion: COVID-19 vaccination may transitorily interfere with cardiac conduction system even in subjects without known underlying heart disease.