Combined Cardiac Arrhythmias Leading to Electrical Chaos Developed in the Convalescent Phase of SARS-CoV-2 Infection: A Case Report and Literature Review

<b>Background</b>: Acute SARS-CoV-2 infection may induce cardiac arrhythmias associated with viral myocarditis, which typically disappear in the convalescent phase after healing of the myocardial inflammation. <b>Methods</b>: We report the case of a 37-year-old woman with a childhood history of atrial septal defect repair and stable normofrequent atrial rhythm, who presented two months post-COVID-19 with palpitations and dizziness. Diagnostic evaluation included cardiac magnetic resonance imaging (CMR), 24 h Holter electrocardiogram (ECG) monitoring, and laboratory assessments over a 3-year period. <b>Results</b>: CMR suggested subacute myocarditis, and Holter ECG revealed multiple discernible complex cardiac arrhythmias including atrial bradycardia, intermittent junctional rhythm (JR), atrial fibrillation (AF), and non-sustained ventricular tachycardia. Laboratory results showed a moderate but transient increase in lactate dehydrogenase, persistently mildly elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP), and immunoglobulin A (IgA), with all other cardiac, inflammatory, immunologic, and organ function parameters remaining normal. In spite of chaotic cardiac rhythm with alternating JR, AF, and atrial normofrequent rhythm with frequent blocked supraventricular beats and increasing atrioventricular conduction time, no therapeutic intervention was necessary during follow-up, and a conservative treatment approach was agreed with the patient. Two years post-COVID-19 infection, the patient returned to a normofrequent atrial rhythm with a markedly prolonged PQ time (500 ms) and a different P wave morphology compared to pre-COVID, without other rhythm disturbances. <b>Conclusions</b>: This case demonstrates a rare pattern of post-viral arrhythmias first emerging in the convalescent phase and resolving spontaneously after two years. It underscores the need for long-term rhythm surveillance following COVID-19, even in patients with prior structural heart disease and a stable baseline rhythm.