Evaluation of serum zonulin levels indicating intestinal permeability in symptomatic heart failure patients

Background: There are few studies evaluating serum zonulin levels indicating intestinal permeability in symptomatic HF patients. In this study, we aimed to evaluate the relationship between serum zonulin levels and echocardiographic parameters before and after treatment for congestion in ischaemic and non-iscchaemic symptomatic HF patients. Methods: Our study was conducted with patients who presented to cardiology outpatient clinics or emergency departments with chronic HF complaints between November 2022 and November 2023. 32 ischaemic and 28 non-ischemic patients who received optimal HF treatment were prospectively included in the study. Simultaneously, 45 healthy controls were recruited. Blood samples were analysed and echocardiographic evaluations were performed before and after treatment. Results: Serum zonulin levels were significantly higher in ischaemic and non-ischemic HF patients (22.9 (12-59), 20.4 (13-78) and 10.1 (6-26) ng/mL, P<0.01) compared with the control group before treatment. Zonulin levels decreased significantly in ischaemic [22.9 (12-59) and 20.9 (10-57) ng/mL, P: 0.03] and non-ischemic HF [20.4 (13-78) and 18.2 (12-57) ng/mL, P: 0.01] groups during the treatment period. However, pre- (P: 0.47) and post-treatment (P: 0.29) values were similar between HF groups. Pretreatment serum zonulin levels were dependently correlated with left ventricular (LV) ejection fraction (EF), right ventricular (RV) basal diameter and C-reactive protein (CRP) levels. Furthermore, there was a negative correlation between serum zonulin levels and LV EF ( b: -0.42, 95% CI: -0.103 to 0.22, P: 0.003) and a positive correlation with RV basal diameter ( b: 0.43, 95% CI: 0.25 to 1.23, P: 0.004) and CRP levels ( b: 0.42, 95% CI: 0.19 to 0.38, P: <0.001). In addition, post-treatment Zonulin levels were negatively correlated with LV EF (p: 0.002). Conclusion: In our study, it was shown that serum Zonulin levels were significantly elevated in HF groups and decreased significantly with congestion-directed HF treatment. Moreover, a significant negative correlation was found between serum Zonulin levels and LV EF before and after treatment. In addition, serum Zonulin levels have been shown to have high sensitivity and specificity in symptomatic HF patients. These results suggest that serum Zonulin levels can be used as a biomarker in both diagnostic and in-hospital treatment follow-up in symptomatic HF patients.