Arrhythmias as Part of Long COVID Syndrome in Hospitalized Patients That Survived a Severe COVID-19 Infection and the Potential Protective Role of Metformin in These Patients

Background: Cardiac arrhythmias are a frequent complication of acute SARS-CoV-2 infection. However, their long-term prevalence and clinical determinants among patients with post-COVID-19 syndrome, especially those previously hospitalized, remain poorly defined. Objectives: To assess the prevalence and types of arrhythmias in long COVID patients following hospitalization and to identify associated clinical risk factors. Methods: In this cross-sectional study, 53 patients previously hospitalized with confirmed COVID-19 were evaluated ≥3 months post-infection. All participants underwent a standardized clinical assessment, 12-lead electrocardiography, and 24 h Holter monitoring. Logistic and Cox regression analyses were performed to identify predictors of arrhythmia. Results: Arrhythmias were identified in 41.5% (n = 22) of patients. Atrial fibrillation (32%) was the most frequent arrhythmia, followed by sinus bradycardia (27%) and sinus tachycardia (18%). Age (OR 1.06, 95% CI 1.01–1.10, p = 0.01) and length of hospital stay (OR 1.1, 95% CI 1.01–1.2, p = 0.04) were independently associated with arrhythmia. Biguanide (metformin) therapy was inversely associated with the occurrence of arrhythmia (Exp(B) = 0.017, p = 0.008). Dyspnea (82.4%) and palpitations (41.5%) were the most commonly reported symptoms. Conclusions: Arrhythmias are common in patients with long COVID following severe disease. Advanced age and prolonged hospitalization are significant risk factors, while biguanide use may offer a protective effect. These findings underscore the need for targeted cardiac surveillance in this population.