Coagulation factors XI and XII as possible targets for anticoagulant therapy.

In this review, we give an overview over observational and experimental studies supporting factors XI and XII as targets for anticoagulant therapy. The majority of observational studies on FXI report low concentrations of FXI to be protective against ischemic stroke and venous thrombosis. There is also extensive evidence from experimental and animal studies supporting FXI inhibition as a target for anticoagulant therapy, alone or in combination with other antithrombotic treatments. Four Phase 2 clinical trials on patients undergoing total knee arthroplasty showed non-inferiority or superiority of FXI inhibition compared to enoxaparin for the primary outcome, which was incidence of venous thromboembolism. One Phase 2 trial reported that FXI inhibition is associated with fewer bleeding events than apixaban. The results from observational studies on FXII are more conflicting. Some show that low FXII concentrations confer protection against thrombosis, while others have found it to be deleterious. Results from experimental studies are inconclusive, but suggest that FXII inhibition might be useful in preventing thrombosis caused by foreign objects like catheters or mechanical heart valves. One Phase 2 study not conducted on thrombosis has reported FXII inhibition as safe. In conclusion, FXI seems to be a promising target for antithrombotic therapy, both alone and in combination with existing therapies, while the potential of targeting FXII is still unclear.

Cardiac Dysfunction and Arrhythmias 3 Months After Hospitalization for COVID-19.

Background The extent of cardiac dysfunction post-COVID-19 varies, and there is a lack of data on arrhythmic burden. Methods and Results This was a combined multicenter prospective cohort study and cross-sectional case-control study. Cardiac function assessed by echocardiography in patients with COVID-19 3 to 4 months after hospital discharge was compared with matched controls. The 24-hour ECGs were recorded in patients with COVID-19. A total of 204 patients with COVID-19 consented to participate (mean age, 58.5 years; 44% women), and 204 controls were included (mean age, 58.4 years; 44% women). Patients with COVID-19 had worse right ventricle free wall longitudinal strain (adjusted estimated mean difference, 1.5 percentage points; 95% CI, -2.6 to -0.5; P=0.005) and lower tricuspid annular plane systolic excursion (-0.10 cm; 95% CI, -0.14 to -0.05; P<0.001) and cardiac index (-0.26 L/min per m2; 95% CI, -0.40 to -0.12; P<0.001), but slightly better left ventricle global strain (-0.8 percentage points; 95% CI, 0.2-1.3; P=0.008) compared with controls. Reduced diastolic function was twice as common compared with controls (60 [30%] versus 29 [15%], respectively; odds ratio, 2.4; P=0.001). Having dyspnea or fatigue were not associated with cardiac function. Right ventricle free wall longitudinal strain was worse after intensive care treatment. Arrhythmias were found in 27% of the patients, mainly premature ventricular contractions and nonsustained ventricular tachycardia (18% and 5%, respectively). Conclusions At 3 months after hospital discharge with COVID-19, right ventricular function was mildly impaired, and diastolic dysfunction was twice as common compared with controls. There was little evidence for an association between cardiac function and intensive care treatment, dyspnea, or fatigue. Ventricular arrhythmias were common, but the clinical importance is unknown. Registration URL: http://clinicaltrials.gov. Unique Identifier: NCT04535154.

Myeloid-related protein-8/14 and C-reactive protein in individuals evaluated for obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) and obesity are often present concomitantly. Their potential contribution to inflammation remains an ongoing debate. The objectives of this study were to investigate whether variables of sleep-disordered breathing are associated with levels of myeloid-related protein-8/14 (MRP-8/14) or C-reactive protein (CRP), and to characterize how adiposity interacts with these associations in individuals evaluated for possible OSA. METHODS: Consecutive individuals referred to Lovisenberg Diakonale Hospital's sleep laboratory between 1st October 2009 and 1st March 2010 were included. We characterized the biomarker distribution sampled the morning after sleep and related these to clinical characteristics and variables recorded during polygraphy or polysomnography. RESULTS: Of the total study population of 222 individuals, 161 (72.5%) were diagnosed with OSA (apnea-hypopnea index (AHI) > or = 5/h). In baseline models (multiple median regression adjusted for age and sex), AHI was independently associated with MRP-8/14 (P=0.025) and CRP (P<0.001). The associations were attenuated after the addition of body mass index (BMI), but remained statistically significant for CRP (P=0.025). However, in final models adjusted for additional factors (systolic blood pressure, cholesterol:high-density lipoprotein ratio, glycosylated haemoglobin, smoking, and cardiovascular disease), only average oxygen saturation for MRP-8/14 (P=0.028) and oxygen desaturation index (ODI) for CRP (P=0.037) remained independent predictors of inflammation, whereas AHI lost its predictive value (MRP-8/14; P=0.30 and CRP; P=0.092). The association between several variables of sleep-disordered breathing and inflammation were stronger in individuals with a higher BMI (P for interaction <0.05 for AHI, nadir oxygen saturation, and time <90% oxygen saturation). CONCLUSIONS: No definitive indication of independent immunological activity resulting from apneas and hypopneas was found in final models adjusted for other factors associated with inflammation, whereas average oxygen saturation for MRP-8/14 and ODI for CRP remained statistically significant predictors. Interactions were observed between BMI and several variables of sleep-disordered breathing on MRP-8/14 and CRP levels.

Obstructive sleep apnea: no independent association to troponins.

BACKGROUND: Cardiac troponins (cTn) are to date the most sensitive and specific biochemical markers of myocardial injury. Abnormal breathing patterns in patients with obstructive sleep apnea (OSA) may cause myocardial cell stress detectable by novel cTn assays. The objectives of this study were to investigate whether a new single-molecule cTnI (S-cTnI) assay and a commercially available high-sensitivity cTnT (hs-cTnT) assay would detect myocyte injury in individuals evaluated for possible OSA, and to explore their relation to variables of disordered breathing during sleep. METHODS: Consecutive individuals referred to Lovisenberg Diakonale Hospital's sleep laboratory between 1 October 2009 and 1 March 2010 were included. We measured cTn in specimens collected the morning after sleep and studied these in relation to variables recorded during polygraphy or polysomnography. RESULTS: All 222 (100 %) individuals had measurable cTn levels using either assay. Stratified into categories according to the apnea-hypopnea index (AHI), patients with OSA (AHI ≥5) had a different distribution of S-cTnI (P = 0.036) and hs-cTnT (P = 0.002) compared to those without (AHI <5). The median (quartiles 1-3) were 3.0 (1.9-6.0) versus 2.3 (1.6-3.8) ng/l for S-cTnI, and 7.0 (5.5-8.7) versus 6.2 (4.9-7.2) ng/l for hs-cTnT. However, in multiple median regression analyses adjusted for conventional predictors, neither S-cTnI (P = 0.57) nor hs-cTnT (P = 0.80) were significantly associated with AHI. CONCLUSIONS: This study reveals no association independent of conventional predictors between OSA and myocardial cell injury measured by S-cTnI and hs-cTnT assays. Our findings support a search for novel biomarkers for prognostication of OSA.

Changes in diagnosing non-ST-segment elevation myocardial infarction after the introduction of a new high-sensitivity cardiac troponin T assay: a single-centre experience.

BACKGROUND: Cardiac troponins are the most sensitive and specific biochemical markers of myocardial injury and with the new high-sensitivity troponin methods very minor injuries of the heart muscle can be detected. The introduction of high-sensitivity assays has facilitated reference range adjustments and a revised cut-off point for myocardial infarction (MI) due to an improved performance in the lower concentration range. The objective of this study was to investigate whether implementing a high-sensitivity cardiac troponin T (hs-cTnT) assay with subsequent lowering of the cut-off point changed the hospital evaluation and diagnosis of acute non-ST-segment elevation myocardial infarction (NSTEMI) in a general hospital population. METHODS: NSTEMI patients admitted to our hospital during two periods each lasting one year were retrospectively compared. During period 1 (August 2007 - July 2008) patients were diagnosed with a conventional troponin T assay, and during period 2 (August 2009 - July 2010) patients were diagnosed using an hs-cTnT assay. RESULTS: A significant increase in the number of NSTEMI admissions was observed using the hs-cTnT assay (225 vs. 341, risk ratio 1.57, 95% confidence interval 1.33 to 1.85). The proportion of patients examined with acute coronary angiography was similar (25.8% vs. 23.8%). Due to the higher number of NSTEMI admissions the total number of angiographies was higher in period 2 (58 vs. 81, p < 0.05), and significantly more patients were examined without signs of coronary artery disease (CAD) (0% vs. 8.6%, p < 0.05). A smaller proportion diagnosed with the high-sensitivity assay had significant dynamic cTnT changes between the highest and lowest cTnT measurement during each admission (96.2% vs. 88.7%, p < 0.01). CONCLUSIONS: More patients were diagnosed with NSTEMI and underwent coronary angiography after introducing the hs-cTnT assay. At the same time there was an increase in the frequency of coronary angiograms without signs of CAD, and fewer had significant dynamic cTnT concentration changes.

Training auscultatory skills: computer simulated heart sounds or additional bedside training? A randomized trial on third-year medical students.

BACKGROUND: The present study compares the value of additional use of computer simulated heart sounds, to conventional bedside auscultation training, on the cardiac auscultation skills of 3rd year medical students at Oslo University Medical School. METHODS: In addition to their usual curriculum courses, groups of seven students each were randomized to receive four hours of additional auscultation training either employing a computer simulator system or adding on more conventional bedside training. Cardiac auscultation skills were afterwards tested using live patients. Each student gave a written description of the auscultation findings in four selected patients, and was rewarded from 0-10 points for each patient. Differences between the two study groups were evaluated using student's t-test. RESULTS: At the auscultation test no significant difference in mean score was found between the students who had used additional computer based sound simulation compared to additional bedside training. CONCLUSIONS: Students at an early stage of their cardiology training demonstrated equal performance of cardiac auscultation whether they had received an additional short auscultation course based on computer simulated training, or had had additional bedside training.

Fibrinogen and fibrin induce synthesis of proinflammatory cytokines from isolated peripheral blood mononuclear cells.

Fibrinogen in plasma includes three main fractions; high-molecular-weight (HMW)-fibrinogen, low-molecular-weight (LMW)-fibrinogen, and very-low-molecular-weight (LMW')-fibrinogen. During acute-phase conditions, plasma fibrinogen levels and the HMW-/LMW-fibrinogen ratio increase rapidly due to increased synthesis of HMW-fibrinogen. The consequences of elevated plasma fibrinogen levels and local deposition of fibrin in inflammatory tissues observed during acute-phase conditions are not clear. We wanted to investigate proinflammatory effects of fibrinogen and fibrin on peripheral blood mononuclear cells (PBMC) as reflected by altered mRNA expression and synthesis of the proinflammatory cytokines IL-6, TNF-alpha and IL-1 beta, and to explore the significance of altered HMW-/LMW-fibrinogen ratio. PBMC were isolated from whole blood using Lymphoprep. HMW-fibrinogen was separated from unfractioned fibrinogen by ammonium sulphate precipitation. Cells were incubated with unfractioned fibrinogen, HMW-fibrinogen or fibrin. Cytokine levels in cell lysates were determined using ELISA assays. Real-time PCR was used for mRNA quantification. We found that fibrinogen significantly increased mRNA levels, and induced synthesis of the proinflammatory cytokines IL-6 and TNF-alpha in PBMC in a dose dependent manner. Median (25, 75 percentile) IL-6 and TNF-alpha concentrations were 12 (5, 40) pg/ml and 16 (0,61) pg/ml, respectively. Median mRNA quantity was increased 12.3- (6.6, 48.6) and 1.7- (1.5, 6.5) fold for IL-6 and TNF-alpha compared to controls. The stimulatory effect of unfractioned fibrinogen was not significantly different from HMW-fibrinogen. Fibrinogen and fibrin were equally effective in promoting cytokine synthesis from PBMC. The results support that fibrin and fibrinogen may actively modulate the inflammatory process by inducing synthesis of proinflammatory cytokines from PBMC.

A daily glass of red wine induces a prolonged reduction in plasma viscosity: a randomized controlled trial.

Moderate red wine consumption has been associated with decreased risk of coronary heart disease. Reduced plasma viscosity and fibrinogen levels have been launched as possible contributors to this risk reduction. The effect of moderate red wine consumption on plasma viscosity, however, has not been investigated in a prospective, randomized trial. We wanted to evaluate the effect of moderate red wine consumption on plasma viscosity, fibrinogen concentration and fibrinogen subfractions. Healthy, nonsmoking volunteers were assigned to consume one glass of red wine daily for 3 weeks in a prospective, randomized cross-over study. In the second 3-week period the volunteers abstained from alcohol use. The plasma viscosity, fibrinogen concentration and the distribution of the main fibrinogen subfractions were determined at inclusion, after wine drinking and after abstention. Plasma viscosity was reduced by 0.026 and 0.024 mPa.s in the two groups following wine intake (95% confidence interval, 0.009-0.043, P = 0.004; 95% confidence interval, 0.0083-0.039, P = 0.003). The decrease in plasma viscosity was maintained following 3 weeks of abstention. The fibrinogen concentration was reduced by 0.17 g/l following wine drinking in the group starting with abstention (95% confidence interval, 0.04-0.29, P = 0.01). The distribution of the fibrinogen subfractions remained unaltered. We conclude that a daily glass of red wine for 3 weeks significantly reduces plasma viscosity. Fibrinogen concentrations are also significantly reduced, when preceded by an abstention period. The decreased viscosity levels are maintained after 3 weeks of abstention, suggesting a sustained viscosity lowering effect of red wine.

Cardiac auscultation training of medical students: a comparison of electronic sensor-based and acoustic stethoscopes.

BACKGROUND: To determine whether the use of an electronic, sensor based stethoscope affects the cardiac auscultation skills of undergraduate medical students. METHODS: Forty eight third year medical students were randomized to use either an electronic stethoscope, or a conventional acoustic stethoscope during clinical auscultation training. After a training period of four months, cardiac auscultation skills were evaluated using four patients with different cardiac murmurs. Two experienced cardiologists determined correct answers. The students completed a questionnaire for each patient. The thirteen questions were weighted according to their relative importance, and a correct answer was credited from one to six points. RESULTS: No difference in mean score was found between the two groups (p = 0.65). Grading and characterisation of murmurs and, if present, report of non existing murmurs were also rated. None of these yielded any significant differences between the groups. CONCLUSION: Whether an electronic or a conventional stethoscope was used during training and testing did not affect the students' performance on a cardiac auscultation test.

The viscosity of fibrinogen subfractions and of EDTA denatured fibrinogen do not differ from that of native fibrinogen.

INTRODUCTION: Fibrinogen is a major determinant of plasma viscosity. The increased risk of atherothrombotic disease associated with a high fibrinogen concentration may partly be attributed to its effect on viscosity. Since the ratio between the three main fibrinogen subfractions high molecular weight (HMW)-, low molecular weight (LMW)-, and very low molecular weight (LMW')-fibrinogen is altered during acute phase conditions, and an increased HMW/LMW-fibrinogen ratio is associated with increased thromboembolic risk, we have examined how these subfractions affect viscosity. The viscosity of plasma is usually determined in ethylenediaminetetra-acetic acid (EDTA) plasma at 37 degrees C. Under such conditions the clotting properties of fibrinogen is affected due to denaturation. Denaturation of plasma proteins may affect their viscosity. Therefore, we have also investigated the effects of EDTA on the viscosity of fibrinogen. MATERIALS AND METHODS: Purified fibrinogen was obtained by beta-alanine precipitation of plasma from healthy donors. Separation of the fibrinogen fractions was performed by gradual precipitation of purified fibrinogen by ammonium sulphate. The viscosity was determined using a Haake Microvisco 2 viscometer. RESULTS: There was no statistically significant difference between the viscosity of native fibrinogen and the three fibrinogen subfractions. A substantial prolongation of the thrombin clotting time was observed in the fibrinogen solution containing EDTA at 37 degrees C compared to 20 degrees C. However, the viscosity of EDTA anticoagulated purified fibrinogen and plasma samples did not differ from that of heparin anticoagulated samples. CONCLUSION: The viscosity of the main fibrinogen subfractions HMW-, LMW- and LMW-fibrinogen did not differ from that of native fibrinogen, and the use of EDTA as anticoagulant did not significantly affect the viscosity of fibrinogen at 37 degrees C.

Influence of freeze-drying on the clotting properties of fibrinogen in plasma.

Freeze-dried plasma standards are often used to calibrate fibrinogen assays. Little is known, however, about the effect of freeze-drying on the clotting properties of fibrinogen. If these properties are altered, the use of freeze-dried calibration standards might influence the results obtained when applying clotting assays to determine fibrinogen concentrations. In order to disclose any discrepancies in fibrinogen concentrations before and after freeze-drying, we determined the fibrinogen concentrations in citrated plasma samples using a total clottable protein method and a clotting-rate assay before and after freeze-drying. When using the clotting-rate assay, significantly higher fibrinogen concentrations were found in fresh-frozen plasma samples compared to freeze-dried samples (P<.001). In freeze-dried plasma samples, the fibrinogen concentrations were significantly higher using the total clottable protein assay than the clotting-rate assay (P<.001). When measuring the fibrinogen concentrations in plasma samples with a wide range of fibrinogen concentrations using the routinely employed clotting-rate assay, significantly higher fibrinogen concentrations were found using the freeze-dried calibration plasma, than the fresh-frozen calibration plasma (P=.02). We conclude that the clotting rate of fibrinogen in citrated plasma is reduced following freeze-drying. When using freeze-dried calibration plasma in a clotting-rate assay, higher fibrinogen concentrations are obtained than by using fresh-frozen plasma. Denaturation of fibrinogen during the freeze-drying process, affecting its polymerization properties, may constitute the main contributor to the reduced clotting rate of freeze-dried plasma.