Abstract
BACKGROUND: Iron deficiency is one of the most common metabolic disorders worldwide and affects multiple organs and systems including the cardiovascular (CV) system. Iron deficiency can cause structural and functional changes in the myocardium. The aim of the study is to evaluate left ventricular (LV) functions in patients with low ferritin levels without anemia by two-dimensional "speckle tracking" echocardiography (2D STE). METHODS: We studied 90 participants (all female) that were divided into two groups according to ferritin levels (49 patients with ferritin levels <30 ng/mL, 41 age-matched controls with >30 ng/mL). Patients with anemia (hemoglobin level <12 g/dL), known CV disease, diabetes mellitus, low ejection fraction (<55%), active infection, high ferritin levels (>200 ng/mL) were excluded. All patients were evaluated by transthoracic echocardiography. In addition to conventional echocardiographic parameters and Doppler measurements, LV global longitudinal strain (GLS) and strain rate (GLSR) were obtained by 2D STE. RESULTS: Mean ferritin level was 18.96 ± 7.29 ng/mL in low ferritin group, and was 61.22 ± 26.14 ng/mL in control group. There were no significant differences according to conventional and Doppler echocardiographic parameters between the groups. LV GLS and GLSR values were significantly lower in low ferritin group comparing with control group (17.31% ± 1.56 and 18.96% ± 1.53, p < 0.001; 0.64 ± 0.13 1/s and 0.81 ± 0.13 1/s, p < 0.001, respectively). There was a significant positive correlation between ferritin levels and LV GLS and GLSR values in study group (r = 0.482, p < 0.001; r = 0.387, p < 0.001, respectively). Ferritin level was also detected as an independent risk factor for GLS value < -18% in logistic regression analysis. In ROC curve analysis, the area under the curve for predicting GLS < -18% was 0.801 (p < 0.001, 95% CI 0.70-0.89) and the threshold of ferritin value was 28.5 ng/mL (sensitivity 76.1%, specificity 77.3%). DISCUSSION: Low ferritin levels can cause subclinical LV systolic dysfunction in patients without anemia. STE provides detailed information about LV functions. With larger studies, these patients should be followed more closely and considered for iron replacement treatment before developing anemia.