The connection between the level of interleukin-6 and the clinical course of acute pulmonary embolism

Abstract

The aim – to investigate the possible influence of the level of interleukin-6 (IL-6) on the clinical course and remodeling of the right ventricle (RV) in patients with acute pulmonary embolism (PE).
Materials and methods. 56 patients with a diagnosis of acute PE, confirmed by сomputed tomographic pulmonary angiography (CTPA), and in whom the level of IL-6 was determined, were studied. The patients were divided into two groups: 1 group with a normal IL-6 level (less than 5.9 pg/ml), 2 group with an elevated IL-6 level (more than 5.9 pg/ml). Clinical and anamnestic and laboratory-instrumental data were analyzed, statistical analysis of the resulting figures was carried out.
Results and discussion. When comparing the groups depending on the level of IL-6, it was found that in group 1, not a single case of high-risk PE was recorded (p=0.052), while there was a significantly higher percentage of moderate-low-risk patients, p<0.05. Patients in group 2 had a higher heart rate (p=0.0006), lower SBP (p=0.04) at admission, and a tendency to increase body mass index (p=0.089). In addition, in group 2, the average levels of leukocytes (p=0.046), d-dimer (p=0.007), CRP (p=0.004) were higher, and the level of lymphocytes (p=0.008) was lower than in group 1, and the trend was determined to an increase in neutrophils (p=0.07) and CPK MB (p=0.89) in the 2nd group. According to the ultrasound data, in group 2 there was more often the detection of thrombosis of the veins of the lower extremities (p=0.003), a significantly larger size of the RV (p=0.02), a tendency to increase the size of the right atrium (RA) and a higher level of systolic pulmonary pressure (p=0.068 ). Analysis of the CTPA showed a greater dilatation of the left LA (p=0.0297) and an increase in the LV/LV index (p=0.0072) in the 2nd group. Correlation analysis revealed an inverse connection with the level of SpO₂ (p=0.03) and lymphocytes (p=0.0065), a direct connection with heart rate (p<0.001), the ratio of LV/LV index (p=0.046), with the level of troponin I (p=0.014), D-dimer (p=0.026), leukocytes (p=0.026), neutrophils (0.038) and glucose (0.016), as well as the trend regarding the connection between the IL-6 level and the size of the RV according to echocardiography (p=0.07) and CPK MB level (p=0.086). The data of ROC analysis showed the connection of dilatation of the RV and Il-6 from the level of more than 7.65 pg/ml, with a sensitivity of the indicator of 90 %, specificity of 50 %.
Conclusions. An Il-6 level increase is more common in elderly patients, patients with venous thrombosis of the lower extremities, tachycardia, hypotension, and with a greater risk of an adverse course during the hospital period. In 2 groups, a higher level of other markers of inflammation (leukocytes, CRP), larger sizes of the RV, a higher level of pulmonary artery pressure according to echocardiography and values of RV/LV according to CTPA results are observed. A direct connection between IL-6 level and heart rate, troponin level, D-dimer level, LV/LV ratio and inverse connection with saturation and lymphocyte level was established according to correlation analysis. Multivariate regression analysis established an independent connection between the IL-6 level and some laboratory (CPK MB, blood glucose) and echocardiographic parameters (RA, LV ESD, LV EDV, LV ESV, LV EF). The threshold level of Il-6, which is accompanied by dilatation of the RV according to Roc-analysis data, was determined.