Tachyarrhythmia is a prognostic factor for severity and mortality in patients with severe fever with thrombocytopenia syndrome

OBJECTIVES: Severe fever with thrombocytopenia syndrome (SFTS) carries high fatality, often complicated by cardiac injury. However, the clinical profile and prognostic significance of tachyarrhythmia in SFTS remain under-investigated. This study aimed to identify risk factors for tachyarrhythmia and evaluate its impact on 30-day mortality. METHODS: We retrospectively reviewed 140 confirmed SFTS patients (2017-2021). Relevant laboratory parameters from the first seven days of onset were evaluated as baseline predictors, and the occurrence of tachyarrhythmia documented at any point during hospitalization was analyzed as the clinical outcome. Multivariate logistic and Cox regression models-force-adjusting for age and viral load-were employed to identify independent risk factors for tachyarrhythmia and predictors of 30-day mortality, respectively. RESULTS: Of 140 patients, 33.5% (47/140) developed clinically relevant cardiac injury, with 57.4% (27/47) of those experiencing tachyarrhythmia. The tachyarrhythmia group showed significantly higher 30-day mortality (48.1% vs 10.0%, P = 0.014). Multivariate analysis identified neutrophil count, platelet count, and potassium as independent risk factors for tachyarrhythmia. Although tachyarrhythmia correlated with poor survival in Kaplan-Meier analysis, only lower platelet count remained an independent prognostic factor for mortality in the Cox model. CONCLUSION: Tachyarrhythmia is a frequent complication in SFTS with cardiac injury and a marker of high mortality risk. Clinical management should emphasize monitoring neutrophils, platelets, and potassium for early risk stratification.