Ischemic stroke is one of the most important neurological disorders [1]. An accurate pathogenic classification of ischemic stroke is essential to prescribe the secondary treatment to prevent recurrences [2]. Cardio-embolic stroke (CES) accounts for 20% of all ischemic strokes (IS) and is more restricting than non-embolic subtypes of stroke [3]. CES has the most unfavorable prognosis, being linked with an increased hazard of death or stroke recurrence [4].
Neurons is a rich source of a variety of enzymes, and any injury like stroke to brain tissue could similarly result in an increase in level of these enzymes in cerebrospinal fluid and serum. Evaluation of these enzyme levels may be an easily available method for the evaluation of severity, course, prognosis, and to some extent in the differential diagnosis of various subtypes of cerebrovascular accidents [5].
D-Dimer and brain natriuretic peptide (BNP) are reported as markers of active coagulation so higher levels reflect more coagulation and larger lesions [6]; d-dimer is the final fibrin degradation product of fibrin-rich thrombi, and its increase is an indicator of thrombus formation and lysis within the left atrium and is the key factor of cardiac embolism onset. Thrombus formation in the cardiac chambers is mainly due to blood stasis, leading to a fibrin-rich clot very similar to venous thrombi. Conversely, thrombi originating in the large arteries are mostly platelet rich, and fibrin formation is secondary to platelet activation [7].
Brain natriuretic peptide is a 32-amino acid polypeptide released primarily from cardiac ventricles on exposure to volume or pressure overload; the ventricular musculature secretes pre-pro-BNP, which is cleaved into a 108-amino acid pro-BNP, which is further cleaved into biologically active BNP (32-amino acid) and the inert NT-pro-BNP (76-amino acid). BNP causes natriuresis, vasodilation, and diuresis, all of which leads to improved myocardial relaxation [8].
Creatine–kinase-MB (CK-MB) as well has been found to be elevated in certain patients with IS, and this elevation was mainly attributed to dysfunction in the sympathetic nervous system due to increased intracranial pressure that induce tachycardia, coronary vasospasm, coronary and peripheral vasoconstriction, and direct myocardial toxicity due to increased intracellular calcium [9].
Elevated C-reactive protein (CRP) in IS subtypes is not clear, may be binding of CRP to phospholipids which are involved in the coagulation cascades and potentially activated by emboli from heart [10].
Different molecules also may behave differently in the pro-thrombotic conditions; albumin synthesis decreases, while other inflammatory globulins rise. Albumin and globulins variations could also be suggestive of a pro-thrombotic state, and globulin/albumin ratio (G/A) correlates with blood viscosity, being a high ratio associated with increased blood viscosity [11].
Aim
This study was to determine the role of BNP, d-dimer, CK-MB, CRP serum levels, and G/A ratio in CES diagnosis and prediction of short-term outcome.
Patients’ and methods
This is a prospective study which was conducted on 96 AIS patients divided to two groups: group Ι: 48 patients with cardio-embolic stroke (CES) and group ΙΙ: 48 patients with ischemic cerebrovascular stroke other than cardio-embolic stroke that include large artery atherosclerosis, small artery occlusion (lacunae), stroke of other determined etiology, and stroke of undetermined etiology (non CES) [12], with first-ever acute ischemic stroke within 24 h of onset of symptoms admitted to Intensive Care and Stroke Unit, Neurology Department, Zagazig University Hospitals, during the period from October 2015 to October 2018. Written informed consent was obtained from all patients or written assent from a relative.
Inclusion criteria
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1.
CES and non- CES diagnosis was according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification criteria. CES include patients with cardiac source of emboli, at least one cardiac source for an embolus, must be identified for a possible or probable diagnosis of cardio embolic stroke. Evidence of a previous systemic embolism supports a clinical diagnosis of cardiogenic stroke. Potential large-artery atherosclerotic sources of thrombosis or embolism should be eliminated. A stroke in a patient with a medium-risk cardiac source of embolism and no other cause of stroke is classified as a possible cardio embolic stroke [12].
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2.
Non-CES were selected to match patients with CES regarding age, sex, and stroke severity.
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3.
Patients with National Institutes of Health Stroke Scale (NIHSS) score more than 5.
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4.
Adult patients with their ages more than 18 year.
Exclusion criteria
This includes lacunar stroke and transient ischemic attacks (TIAs);hemorrhagic stroke; other neurological causes of acute focal cerebral dysfunction such as cerebral venous sinus thrombosis, head trauma, infection, and auto immune disorders; heart failure; liver failure; and chronic renal disease.
All patients were subjected to full-detailed neurological history with stressing on the vascular and cardiac risk factors and general and neurological examination. Glasgow Coma Scale (GCS) is used to detect the depth of coma [13], and stroke severity was assessed using the National Institutes of Health Stroke Scale (NIHSS) [14].
Laboratory investigations
Fifteen milliliters of venous blood was obtained from the patients within the first 24 h of stroke. All routine and special laboratory investigations were done at Clinical pathology department, Zagazig University Hospitals including CBC, liver function, kidney function, ESR, and lipid profile.
Brain natriuretic peptide
Four milliliters of blood was placed in a polypro pane tube containing a mixture of sodium salt of ethylene diamine tetra acetic acid (EDTA) at a concentration of 1 mg/ml of blood and aprotinin at a concentration of 500 kallikerin inhibitory unit (kiu)/ml of blood serving as a natural proteinase inhibitor which acts as a preservative for natriuretic peptides, then mixing of the blood was done. Then, the tube was centrifuged at 5000 rpm for 15 min in the cool centrifuge, the separated serum was stored at − 70 °C until analysis.
Later on, the assay was done using human BNP Elisa kits (Spain react kits sr 19369u) which are immune-sorbent assays for quantitative measurement; the least sensitivity is 14 pg/ml and ranges from 14 to 1000 pg/ml [15].
D-dimer
Three milliliters of blood was collected within vacuum tubes containing 0.5 ml buffered sodium citrate before the initiation of any oral, enteral, or parenteral feeding or medications. Blood samples were mixed well with avoiding of foam formation then immediately centrifuged at 3000 rpm for 15 min at ambient room temperature, and the plasma is separated. d-Dimer was measured turbidmetry (SAT Liatest D-Di; Diagnostica STAGO) on the STAgo compact analyzer; normal value is less than 500 ng/ml [16].
Creatine–kinase-MB
Four milliliters of blood was derived within a plastic tube centrifuged at 4000 rpm for 3 min; the separated serum was assayed for CK-MB using Spain react kits with normal value up to 2.8 ng/L [17].
C-reactive protein
Four milliliters was withdrawn in a plastic tube centrifuged at 4000 rpm for 3 min, the separated serum used for analysis of CRP is measured using Olympus 640 analyzer with a normal value up to 5 mg/L.
Globulin/albumin ratio (G/A) was calculated with normal ratio 0.6–0.7 [11].
All patients were evaluated by Brain CT or MRI for diagnosis of ischemic stroke.
Each patient underwent electrocardiogram, echocardiography, and carotid Doppler ultrasonography to define etiological stoke subtype.
The short-term outcome was evaluated in all patients at the third week of stroke onset using modified Rankin scale (mRS) ranging from zero (no symptoms at all) to 6 (dead). Outcome was defined as good if mRS = 0–2, bad (poor) if mRS = 3–5, and death if mRS = 6 [18].
Statistical analysis
Descriptive statistical methods were used to calculate means and standard deviation (SD). For comparisons with the continuous variables, Student’s t test was used. The sensitivity and specificity of biomarkers in diagnosis of CES and poor outcome prediction were also assessed by a receiver operating characteristic (ROC) curve. Logistic regression analysis was used to calculate the odds ratios (OR) and 95% confidence intervals (CI) for risk estimation. A p value of less than 0.05 was considered statistically significant. The data were tabulated and statistically analyzed using the software SPSS version 20 [19].