Free Triiodothyronine as a Biomarker for Ventricular Arrhythmia Following Myocardial Infarction: A Multicenter Prospective Cohort Study

Background: The relationship between plasma free triiodothyronine (FT3) levels and the risk of ventricular arrhythmias (VA) in patients with acute myocardial infarction (AMI) remains unclear. Objective: This study aimed to investigate whether the level of FT3 influences VA in patients with AMI. Methods: A multicenter prospective study was conducted to collect patients diagnosed with AMI from three centers between January 2018 and December 2021. Patients were categorized into VA and Non-VA groups. FT3 levels were compared between groups, and multivariate logistic regression analyses were performed to evaluate the relationship. Results: A total of 3277 consecutive patients (mean age: 64.6 years) were included, with 123 (3.9%) developing VA during hospitalization. The VA group had significantly lower FT3 levels compared to the Non-VA group ([3.74 ± 0.77 pmol/L] vs [4.13 ± 0.81 pmol/L], P < 0.001). Multivariate analysis identified FT3 level as an independent predictor of VA risk (adjusted odds ratio [OR]: 0.761; 95% confidence interval [CI]: 0.591– 0.980; P = 0.035). A dose-dependent association was observed, with progressively lower VA risks across increasing FT3 quartiles ( P trend = 0.007). Each 1 standard deviation decrease in FT3 levels was associated with a 19.9% increased VA risk (OR = 0.801; 95% CI: 0.651– 0.984; P = 0.035). Conclusion: This study confirmed a significant association between plasma FT3 levels and the risk of ventricular arrhythmias during hospitalization in patients with myocardial infarction. Low FT3 levels are associated with an increased risk of VA in patients with AMI. Keywords: free triiodothyronine, acute myocardial infarction, ventricular arrhythmia, biomarker, prospective cohort study, diagnosis and prediction