Cardiovascular Journal of Africa: Vol 32 No 5 (SEPTEMBER/OCTOBER 2021)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 5, September/October 2021 AFRICA 245 There was no statistically significant correlation between pericardial SCUBE1 levels and gender, hypertension, diabetes mellitus, smoking, peripheral artery disease, chronic obstructive pulmonary disease, and left main coronary artery lesions in all groups. On the other hand, a statistically significant relationship was found between arterial SCUBE1 and smoking; arterial SCUBE1 levels of smokers were significantly higher than those of non-smokers ( p = 0.037). There was no statistically significant relationship between pre-operative variables such as gender, hypertension, diabetes, smoking, peripheral arterial disease, chronic obstructive pulmonary disease and left main coronary artery lesion and pericardial or arterial SCUBE1 values in groups 1, 2 and 3 patients. Correlations between age, ejection fraction, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and troponin variables, and pericardial and arterial SCUBE1 values are shown in Table 3. No statistically significant relationship was found between all these groups. Pericardial SCUBE1 levels in STEMI patients who needed peri-operative temporary cardiac pacing were statistically significantly higher ( p = 0.034) than in the other groups (Table 4). The relationship between the variables of postoperative atrial fibrillation, stroke, revision and long-term intensive care unit stay, and pericardial and arterial SCUBE1 values were evaluated with the t -test in independent groups and no statistically significant relationship was found. However, a statistically significant relationship was found between high pericardial SCUBE1 levels and the requirement for postoperative intra-aortic balloon pump support ( p = 0.003) (Table 5). Discussion In patients scheduled for coronary revascularisation, certain parameters may be helpful in predicting postoperative morbidity and mortality. These parameters are of great importance for prognosis and for effective follow-up treatment. The goal of this study was to investigate SCUBE1 levels in arterial and pericardial fluid samples of patients who had undergone CABG surgery, and the effect of SCUBE1 levels on postoperative outcomes. SCUBE1 is a molecule that is secreted from the cellular surface and is associated with early embryogenesis. It is an emerging secreted glycoprotein that can form oligomers and manifests a stable association with the human vascular endothelial cell surface. 7 Deposition of SCUBE1 into the subendothelial matrix of atherosclerotic plaques was evidenced by immunohistochemistry. SCUBE1 protein is predominantly expressed in platelets and can be proteolytically modified to release a smaller, active fragment to be associated with thrombus, and localised with the subendothelial matrices in atherosclerotic plaque. One gene family identified by this approach encoded secreted proteins harbouring a signal peptide at the amino terminus, followed by nine copies of EGF-like repeats and one CUB domain at the carboxyl terminus. Therefore, these genes were named SCUBE for signal peptide-CUB EGF-like domain- containing proteins. In addition, a spacer region containing multiple potential N-linked glycosylation sites is located between the EGF-like repeats and the CUB domain in these proteins. SCUBE1 was identified and subsequently mapped onto human chromosome 22q13. SCUBE1 is expressed in a variety of embryonic tissues, therefore it may play critical roles during embryogenic development. 7,8 The pericardial space is actually an aperture of capillaries. It is a fibrous-serosal conical sac enclosing the roots of the aorta and the pulmonary artery. Pericardial fluid is a product of ultrafiltration by mesothelial cells and is considered to be drained mainly by the lymphatic capillary bed. Under normal conditions, it provides lubrication for the beating heart, while the mesothelial cells that line the membrane may also have a role in the absorption of pericardial fluid, along with the pericardial lymphatics. The pericardial fluid volume is determined by the equilibrium between production and drainage. It is considered to be a plasma ultrafiltration product, like other serosal cavity fluids. Studies in human normal pericardial fluid have shown the presence of a heterogeneous cell population and different amounts of fluid can be detected depending on the circumstances. 9 Normal pericardial fluid is a transudate and pericardial fluid osmomolarity is lower Table 3. Correlation analysis of clinical and demographic variables and pericardial and arterial SCUBE1 levels Variables Group 1 Group 2 Group 3 Group 4 Pericardial Arterial Pericardial Arterial Pericardial Arterial Pericardial Arterial Gender 0.472 0.7 0.314 0.166 0.621 0.861 0.605 0.884 EF 0.216 0.586 0.855 0.278 0.013 0.273 0.915 0.614 HDL-C 0.261 0.699 0.451 0.775 0.352 0.481 0.515 0.891 LDL-C 0.461 0.667 0.147 0.570 0.597 0.555 0.471 0.13 Troponin 0.885 0.804 0.739 0.743 0.823 0.324 0.875 0.672 EF: ejection fraction; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; Pericardial: pericardial fluid SCUBE1; Arterial: arte- rial blood SCUBE1. Table 4. Postoperative variables of STEMI patients and pericardial SCUBE1 levels Variable Groups Number of patients Mean Standard deviation t p -value LIMA No 6 0.050 0.069 –0.500 0.619 Yes 48 0.803 3.658 Pacemaker No 53 0.583 3.337 –2.180 0.034 Yes 1 7.925 – LIMA: left internal mammarian artery. Table 5. Postoperative variables of USAP patients and pericardial SCUBE1 levels Variable Groups Number of patients Mean Standard deviation t p -value Intra-aortic balloon pump No 48 0.109 0.251 –3.102 0.003 Yes 1 0.896 –