Stimulators of the soluble guanylyl cyclase: promising functional insights from rare coding atherosclerosis-related GUCY1A3 variants.

Stimulators of the soluble guanylyl cyclase (sGC) are emerging therapeutic agents in cardiovascular diseases. Genetic alterations of the GUCY1A3 gene, which encodes the α1 subunit of the sGC, are associated with coronary artery disease. Studies investigating sGC stimulators in subjects with CAD and carrying risk-related variants in sGC are, however, lacking. Here, we functionally investigate the impact of coding GUCY1A3 variants on sGC activity and the therapeutic potential of sGC stimulators in vitro. In addition to a known loss-of-function variant, eight coding variants in GUCY1A3 were cloned and expressed in HEK 293 cells. Protein levels and dimerization capability with the ß1 subunit were analysed by immunoblotting and co-immunoprecipitation, respectively. All α1 variants found in MI patients dimerized with the ß1 subunit. Protein levels were reduced by 72 % in one variant (p < 0.01). Enzymatic activity was analysed using cGMP radioimmunoassay after stimulation with a nitric oxide (NO) donor. Five variants displayed decreased cGMP production upon NO stimulation (p < 0.001). The addition of the sGC stimulator BAY 41-2272 increased cGMP formation in all of these variants (p < 0.01). Except for the variant leading to decreased protein level, cGMP amounts reached the wildtype NO-induced level after addition of BAY 41-2272. In conclusion, rare coding variants in GUCY1A3 lead to reduced cGMP formation which can be rescued by a sGC stimulator in vitro. These results might therefore represent the starting point for discovery of novel treatment strategies for patients at risk with coding GUCY1A3 variants.

Prognostic Value of Plasma B-Type Natriuretic Peptide in the Long-Term Follow-up of Patients With Transposition of the Great Arteries With Morphologic Right Systemic Ventricle After Atrial Switch Operation.

BACKGROUND: B-type natriuretic peptide (BNP) is an established marker for heart failure assessment, but the prognostic quality of BNP after atrial switch operation (ASO) has not yet been elucidated. METHODS AND RESULTS: In 89 patients (median age, 24 years; range, 15-35 years) after ASO, BNP was measured. During a 48-months follow-up we focused on critical cardiac events, defined as decompensation, sudden cardiac death or need for heart transplantation. BNP was considerably lower in 81 patients in functional class (FC) I/II (median, 35 pg/ml; range, 3-586 pg/ml) than in 6 patients in FC III/IV (median, 246 pg/ml; range, 14-1,150 pg/ml, P≤0.073). BNP was significantly higher after Mustard than after Senning procedure (P≤0.030). There was no significant difference in BNP between simple or complex transposition of the great arteries (TGA) (P≤0.44). Eleven subjects (13%, 95% CI: 7-22%) had a critical cardiac event within 48 months. On ROC analysis BNP had a high predictive value regarding discrimination of patients with and without critical events (area under the ROC curve, 0.90; 95% CI: 0.76 to >0.99, P<0.001). The cut-off was 85 pg/ml (sensitivity, 88%; specificity, 85%). Additionally, estimated event-free-survival was longer after Senning than after Mustard procedure (P≤0.017). There was no significant difference in outcome between patients with simple or complex TGA with regard to occurrence of critical events. CONCLUSIONS: BNP is a sensitive and specific prognostic marker for critical cardiac events after ASO.

An Automated Assay for Growth Differentiation Factor 15.

BACKGROUND: Growth differentiation factor 15 (GDF-15) can serve as a biomarker for cardiovascular disease burden and risk. We evaluated a new, fully automated electrochemiluminescence immunoassay for measuring GDF-15. METHODS: Six laboratories independently characterized the Elecsys® GDF-15 assay (Roche Diagnostics) under routine conditions. Within-run precision (repeatability), within-laboratory precision (intermediate precision), and between-laboratory precision (reproducibility) were assessed. Plasma-serum sample correlation, reagent lot-to-lot reproducibility, and instrument comparisons were performed. The Elecsys assay was compared to a research immunoradiometric assay (IRMA) and a commercially available ELISA. GDF-15 concentrations were measured with the Elecsys assay in 739 apparently healthy individuals. RESULTS: CVs for within-run and within-laboratory precision ranged from 0.7% to 7.7% and 1.7% to 8.6%, respectively, for samples containing 670-16039 ng/L. CVs for between-laboratory precision ranged from 7.1% to 8.9% (766-14289 ng/L). Recovery of GDF-15 was comparable for serum, Li-heparin plasma, K2- and K3-EDTA plasma, and citrated plasma, between 2 reagent lots, and on the cobas e 411 and cobas e 601 analyzers (Roche Diagnostics). GDF-15 concentrations in the clinically relevant range (400-3000 ng/L) measured with the Elecsys assay showed a good correlation and agreement with those measured by IRMA or ELISA. GDF-15 concentrations in apparently healthy individuals increased with age but did not vary by sex. CONCLUSIONS: The Elecsys GDF-15 assay demonstrates a robust analytic performance under routine conditions and provides an automated method for measuring GDF-15 concentrations in serum and plasma.

Multi-centre investigation on reference ranges for ROTEM thromboelastometry.

Reagent-supported thromboelastometry (TEM) with the ROTEM Whole Blood Haemostasis Analyser is an enhancement of thromboelastography, a method that is increasingly used for the point of care monitoring of acute perioperative bleeding disorders. We investigated the reference ranges of two activated tests (INTEM and EXTEM) and a test analysing specifically the fibrin component of coagulation (FIBTEM) in a multi-centre approach. The reference ranges obtained for the clotting time (CT), clot formation time (CFT), alpha angle (ALP), maximum clot firmness (MCF) and clot lysis parameters were comparable from centre to centre. INTEM: CT equals; 137-246 s, CFT equals; 40-100 s, MCF equals; 52-72 mm. EXTEM: CT equals; 42-74 s, CFT equals; 46-148 s, MCF equals; 49-71 mm. FIBTEM: MCF equals; 9-25 mm. ROTEM whole blood coagulation correlated weakly with a trend towards enhanced coagulation in females compared with males and in advanced age. The repeatability (within-run imprecision) of the results was dependent on the test with the following coefficients of variation: 1-5% (clot firmness, alpha angle), 3-12% (CT, CFT), 6-13% (FIBTEM clot firmness). Citrated blood samples were stable for ROTEM analysis stored within 6 h from drawing. In summary, the data showed that ROTEM thromboelastometry yields consistent values between centres and that providing general orientating reference ranges seems to be possible.

High-dose aprotinin reduces activation of hemostasis, allogeneic blood requirement, and duration of postoperative ventilation in pediatric cardiac surgery.

BACKGROUND: Though multiple studies have affirmed the effectiveness of aprotinin in reducing blood loss in adult cardiac surgery, the possible benefit in pediatric cardiac surgery is controversial. METHODS: In a double-blind, randomized, and placebo-controlled study, the efficacy of aprotinin in attenuating the hemostatic and inflammatory activation during cardiopulmonary bypass in 60 patients weighing less than 10 kg was investigated. Secondary endpoints were the influence of aprotinin on the reduction of blood loss and allogeneic blood requirement, as well as postoperative oxygenation and length of mechanical ventilation. Aprotinin was administered in a high-dose of 3 x 10(4) KIU/kg plus a bolus of 5 x 10(5) KIU (not weight adjusted) added to the pump prime. RESULTS: Aprotinin plasma concentration at the end of cardiopulmonary bypass (CPB) was with 184 +/- 45 KIU/mL, within the targeted range of 200 KIU/mL. Coagulation and fibrinolysis were suppressed (F1.2 1 hour after CPB: 5.35 +/- 2.9 nmol/L vs 14.5 +/- 23.1 nmol/L; D-dimer 1 hour after CPB: 0.63 +/- 0.6 ng/mL vs 2.3 +/- 3.1 ng/mL; p < 0.05), inflammatory markers (interleukin [IL]-6, IL-8, IL-10) increased over time without significant differences between the groups, and only complement C3a activation was significantly attenuated at the end of CPB in the aprotinin group. Chest tube drainage was significantly reduced (24 hours: median 13.5 [IQR 12.2] mL/kg vs 19.4 [8.2] mL/kg; p < 0.05). All patients received one unit of packed cells to prime the heart lung machine. A second unit was needed significantly less often in the aprotinin group (13% vs 47%; p < 0.05). Postoperative oxygenation (pO2/FIO2 172 [IQR 128] mm Hg vs 127 [74]; p < 0.05) improved, and the time on ventilator was shorter in the aprotinin group (median 45 hours [IQR 94] vs 101 [IQR 74]; p < 0.05). No side effects were attributable to the use of aprotinin. CONCLUSIONS: High-dose aprotinin effectively attenuated hemostatic activation and reduced blood loss and transfusion requirement in pediatric cardiac surgery. Postoperative ventilation was also shortened in the aprotinin group.

Chronic dysfunction of the endothelium is associated with mortality in acute coronary syndrome patients.

INTRODUCTION: Platelet activation and endothelium dysfunction are determinants of atherothrombosis in acute coronary syndrome (ACS) patients. The aim of this study was to investigate the relationship between platelet and endothelial cell activation markers and mortality in patients presenting with ACS. MATERIALS AND METHODS: Plasma levels of RANTES, Neutrophil Activating Protein-2 (NAP-2), Thrombospondin-1 (TSP-1), Von Willebrand Factor (VWF), Von Willebrand Factor Propeptide (VWF:pp) and Osteoprotegerin (OPG) were measured in a cohort study of 339 consecutive ACS patients who underwent percutaneous coronary interevention (PCI). The primary endpoint was 4-year mortality. RESULTS: There were 46 deaths during the follow up. Median values of VWF (12.2µg/mL versus 7.86µg/mL, P=0.001) and VWF:pp (7.34nM versus 6.17nM, P=0.011) were higher in non-survivors compared to survivors. High levels of OPG were found in 37 patients: 27 of them were survivors (9.2%) and 10 were non-survivors (21.7%, P=0.011). Kaplan-Meier estimates of mortality for VWF were 7.5% in the first quartile (n=6 deaths), 12.2% in the second quartile (n=10 deaths), 11.2% in the third quartile (n=9 deaths) and 25% in the fourth quartile (n=21 deaths) of VWF (P=0.004). There was a 27.8% of probability of mortality when high OPG was measured versus 12.4% when low OPG was measured (P=0.007). No relationship between baseline platelet activation markers and mortality was found. CONCLUSION: In patients with ACS undergoing PCI, increased chronic endothelial cell activation and dysfunction is associated with an increased risk of long-term mortality.

Iron deficiency in a patient with extreme erythrocytosis due to cyanotic congenital heart disease.

Erythrocytosis is an adaptive response to improve oxygen transport in cyanotic congenital heart disease (CCHD). However, at highly increased hematocrit levels patients may experience hyperviscosity symptoms. Iron deficiency in CCHD patients is often overlooked due to elevated hemoglobin concentrations. A 29-year-old male with CCHD was readmitted to our outpatient clinic. Red blood cells (11.65*10(12)/L), hemoglobin (25.7 g/dL), and hematocrit (80%) were extremely elevated. Measurements of iron supply showed a constellation typical for iron deficiency with low ferritin (13.2 microg/L), and high sTfR (20 mg/L). We present a case of extremely high red blood cell counts with concomitant iron deficiency. For appropriate management and to avoid misinterpretation of the iron status, ferritin and sTfR should always accomplish laboratory examination of CCHD patients.

Analytical performance of the new coagulation monitoring system INRatio for the determination of INR compared with the coagulation monitor Coaguchek S and an established laboratory method.

An evaluation of the INRatio Prothrombin Time Monitoring system for determination of INR was done in two centers with a total of 5 healthy subjects and 77 subjects on oral anticoagulation. The INRatio and the Coaguchek S were compared with an established laboratory method. The correlation coefficient of the comparison with the laboratory was r=0.954 for INRatio and r=0.937 for Coaguchek S. The mean relative deviation from the lab method calculated according to Hill was 6.87% for INRatio, which is rated "very goo", and 9.72% for Coaguchek S ("goo"). The imprecision in the normal range (INR=1.1) showed a coefficient of variation (CV) of 7.8% and a standard deviation (SD) of 0.09. In the therapeutic range (INR 3.9) the CV was 5.4%, the SD 0.21 and above therapeutic range (INR 5.3), the CV was 8.4% (SD 0.44), rated satisfactory. The concordances of the compared methods with the routine were 81% for INRatio and 79% for Coaguchek S, which is considered state-of-the-art. Most of the patients' perceptions of the INRatio were very positive. In the hands of professionals the INRatio demonstrated very good accuracy and precision and an excellent technical reliability. Further studies using INRatio for self testing by patients are warranted.

The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery.

UNLABELLED: Hemorrhage after cardiopulmonary bypass (CPB) remains a clinical problem. Point-of-care tests to identify hemostatic disturbances at the bedside are desirable. In the present study, we evaluated the predictive value of two point-of-care tests on postoperative bleeding after routine cardiac surgery. Prospectively, 255 consecutive patients were studied to compare the ability of modified thromboelastography (ROTEG) as well as a platelet function analyzer (PFA-100) to predict postoperative blood loss. Measurements were performed at three time points: preoperatively, during CPB, and after protamine administration with three modified thromboelastography and PFA tests. The best predictors of increased bleeding tendency were the tests performed after CPB. The angle alpha is the best predictor (area under the receiver operating characteristic curve 0.69) and, in combination with the adenosine diphosphate-PFA test, the predictive accuracy is enhanced (area under the receiver operating characteristic curve 0.73). The negative predictive value for the angle alpha is 82%, although the positive predictive value is small (41%). Thromboelastography is a better predictor than PFA. In routine cardiac surgery, impaired hemostasis as identified by point-of-care tests does not inevitably lead to hemorrhage postoperatively. However, patients with normal test results are unlikely to bleed for hemostatic reasons. Bleeding in these patients is probably caused surgically. The high negative predictive value supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. IMPLICATIONS: Thrombelastography and platelet function analysis in routine cardiac surgery demonstrate high negative predictive values for postoperative bleeding, which supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. The positive predictive values are small. The best predictors are thrombelastography values obtained after cardiopulmonary bypass.