Bjørn Bendz

Association between acute hypobaric hypoxia and activation of coagulation in human beings

The risk of venous thrombosis is thought to be increased by flying. In a study of 20 healthy male volunteers who were suddenly exposed to a hypobaric environment similar to that encountered within aeroplane cabins, markers of activated coagulation transiently Increased by two-fold to eight-fold. We suggest that hypobaric hypoxia, with sedentariness and dehydration, may cause this increased risk of venous thrombosis.

Drug-Eluting or Bare-Metal Stents for Coronary Artery Disease

BACKGROUND Limited data are available on the long-term effects of contemporary drug-eluting stents versus contemporary bare-metal stents on rates of death, myocardial infarction, repeat revascularization, and stent thrombosis and on quality of life. METHODS We randomly assigned 9013 patients who had stable or unstable coronary artery disease to undergo percutaneous coronary intervention (PCI) with the implantation of either contemporary drug-eluting stents or bare-metal stents. In the group receiving drug-eluting stents, 96% of the patients received either everolimus- or zotarolimus-eluting stents. The primary outcome was a composite of death from any cause and nonfatal spontaneous myocardial infarction after a median of 5 years of follow-up. Secondary outcomes included repeat revascularization, stent thrombosis, and quality of life. RESULTS At 6 years, the rates of the primary outcome were 16.6% in the group receiving drug-eluting stents and 17.1% in the group receiving bare-metal stents (hazard ratio, 0.98; 95% confidence interval [CI], 0.88 to 1.09; P=0.66). There were no significant between-group differences in the components of the primary outcome. The 6-year rates of any repeat revascularization were 16.5% in the group receiving drug-eluting stents and 19.8% in the group receiving bare-metal stents (hazard ratio, 0.76; 95% CI, 0.69 to 0.85; P<0.001); the rates of definite stent thrombosis were 0.8% and 1.2%, respectively (P=0.0498). Quality-of-life measures did not differ significantly between the two groups. CONCLUSIONS In patients undergoing PCI, there were no significant differences between those receiving drug-eluting stents and those receiving bare-metal stents in the composite outcome of death from any cause and nonfatal spontaneous myocardial infarction. Rates of repeat revascularization were lower in the group receiving drug-eluting stents. (Funded by the Norwegian Research Council and others; NORSTENT ClinicalTrials.gov number, NCT00811772 .).

Invasive versus conservative strategy in patients aged 80 years or older with non-ST-elevation myocardial infarction or unstable angina pectoris (After Eighty study): an open-label randomised controlled trial

BACKGROUND Non-ST-elevation myocardial infarction (NSTEMI) and unstable angina pectoris are frequent causes of hospital admission in the elderly. However, clinical trials targeting this population are scarce, and these patients are less likely to receive treatment according to guidelines. We aimed to investigate whether this population would benefit from an early invasive strategy versus a conservative strategy. METHODS In this open-label randomised controlled multicentre trial, patients aged 80 years or older with NSTEMI or unstable angina admitted to 16 hospitals in the South-East Health Region of Norway were randomly assigned to an invasive strategy (including early coronary angiography with immediate assessment for percutaneous coronary intervention, coronary artery bypass graft, and optimum medical treatment) or to a conservative strategy (optimum medical treatment alone). A permuted block randomisation was generated by the Centre for Biostatistics and Epidemiology with stratification on the inclusion hospitals in opaque concealed envelopes, and sealed envelopes with consecutive inclusion numbers were made. The primary outcome was a composite of myocardial infarction, need for urgent revascularisation, stroke, and death and was assessed between Dec 10, 2010, and Nov 18, 2014. An intention-to-treat analysis was used. This study is registered with ClinicalTrials.gov, number NCT01255540. FINDINGS During a median follow-up of 1·53 years of participants recruited between Dec 10, 2010, and Feb 21, 2014, the primary outcome occurred in 93 (40·6%) of 229 patients assigned to the invasive group and 140 (61·4%) of 228 patients assigned to the conservative group (hazard ratio [HR] 0·53 [95% CI 0·41-0·69], p=0·0001). Five patients dropped out of the invasive group and one from the conservative group. HRs for the four components of the primary composite endpoint were 0·52 (0·35-0·76; p=0·0010) for myocardial infarction, 0·19 (0·07-0·52; p=0·0010) for the need for urgent revascularisation, 0·60 (0·25-1·46; p=0·2650) for stroke, and 0·89 (0·62-1·28; p=0·5340) for death from any cause. The invasive group had four (1·7%) major and 23 (10·0%) minor bleeding complications whereas the conservative group had four (1·8%) major and 16 (7·0%) minor bleeding complications. INTERPRETATION In patients aged 80 years or more with NSTEMI or unstable angina, an invasive strategy is superior to a conservative strategy in the reduction of composite events. Efficacy of the invasive strategy was diluted with increasing age (after adjustment for creatinine and effect modification). The two strategies did not differ in terms of bleeding complications. FUNDING Norwegian Health Association (ExtraStiftelsen) and Inger and John Fredriksen Heart Foundation.

Layer-Specific Quantification of Myocardial Deformation by Strain Echocardiography May Reveal Significant CAD in Patients With Non–ST-Segment Elevation Acute Coronary Syndrome

OBJECTIVES Our objective was to assess whether patients with significant coronary artery disease (CAD) had reduced endocardial function assessed by layer-specific strain compared with patients without significant CAD. BACKGROUND The left ventricular (LV) wall of the heart comprises 3 myocardial layers. The endocardial layer is most susceptible to ischemic injury. METHODS Seventy-seven patients referred to coronary angiography due to suspected non-ST-segment elevation-acute coronary syndromes (NSTE-ACS) were prospectively included. Coronary occlusion was found in 28, significant stenosis in 21, and no stenosis in 28 patients. Echocardiography was performed 1 to 2 h before angiography. Layer-specific longitudinal and circumferential strains were assessed from endocardium, mid-myocardium, and epicardium by 2-dimensional (2D) speckle-tracking echocardiography (STE). Territorial longitudinal strain (TLS) was calculated based on the perfusion territories of the 3 major coronary arteries in a 16-segment LV model, whereas global circumferential strain (GCS) was averaged from 6 circumferential LV segments in all 3 layers. RESULTS Patients with significant CAD had worse function in all 3 myocardial layers assessed by TLS and GCS compared with patients without significant CAD. Endocardial TLS (mean -14.0 ± 3.3% vs. -19.2 ± 2.2%; p < 0.001) and GCS (mean -19.3 ± 4.0% vs. -24.3 ± 3.4%; p < 0.001) were most affected. The absolute differences between endocardial and epicardial TLS and GCS were lower in patients with significant CAD (Δ2.4 ± 3.6% and Δ6.7 ± 3.8%, respectively) than in those without significant CAD (Δ5.3 ± 2.1% and Δ10.4 ± 3.0%; p < 0.001). This reflects a pronounced decrease in endocardial function in patients with significant CAD. A receiver-operating characteristic curve analysis showed that endocardial and mid-myocardial TLS were superior to identify significant CAD compared with epicardial TLS (p < 0.05), wall motion score index (p < 0.01), and ejection fraction (EF) (p < 0.001). CONCLUSIONS Assessment of layer-specific strain by 2D-STE might identify NSTE-ACS patients with significant CAD. Endocardial function was more affected in patients with significant CAD compared with epicardial function and EF.

The Terminal Part of the QT Interval (T peak to T end): A Predictor of Mortality after Acute Myocardial Infarction

Background: The terminal part of the QT interval (T peak to T end; Tp‐e)—an index for dispersion of cardiac repolarization—is often prolonged in patients experiencing malignant ventricular arrhythmias after acute myocardial infarction (AMI). We wanted to explore whether high Tp‐e might predict mortality or fatal arrhythmia post‐AMI.

Physiological Function of Tissue Factor Pathway Inhibitor and Interaction with Heparins

Tissue factor pathway inhibitor (TFPI) is now recognized as a major physiological anticoagulant. Its main role is to modulate factor VIIa/tissue factor catalytic activity. Another important role is to potentiate the effect of heparins. TFPI is released from the vascular endothelium after injection of either unfractionated heparin (UFH) or low-molecular-weight heparins (LMWHs), which may then provide high concentrations of TFPI at sites of tissue damage and ongoing thrombosis. In dilute prothrombin-time-based assays, released TFPI contributes approximately one-third to the anticoagulant effect of heparin, the remaining being accounted for by antithrombin. Released TFPI, but not plasma TFPI, contains the basic carboxy-terminal tail which is important for the anticoagulant effect. UFH and LMWH exert differential effects on intravascular TFPI. UFH, but not LMWH, given in therapeutic doses, is associated with a progressive depletion of TFPI, which is associated with a strong rebound activation of coagulation after cessation of treatment. Such depletion may explain the apparent superior efficacy of LMWH observed in clinical trials.

Effect of a single dose of the interleukin-6 receptor antagonist tocilizumab on inflammation and troponin T release in patients with non-ST-elevation myocardial infarction: a double-blind, randomized, placebo-controlled phase 2 trial

AIMS Interleukin-6 (IL-6) contributes to atherosclerotic plaque destabilization and is involved in myocardial injury during ischaemia-reperfusion. Interleukin-6 is therefore a potential therapeutic target in myocardial infarction (MI). We hypothesized that the IL-6 receptor antagonist tocilizumab would attenuate inflammation, and secondarily reduce troponin T (TnT) release in non-ST-elevation MI (NSTEMI). METHODS AND RESULTS In a two-centre, double-blind, placebo-controlled trial, 117 patients with NSTEMI were randomized at a median of 2 days after symptom onset to receive placebo (n = 59) or tocilizumab (n = 58), administered as a single dose prior to coronary angiography. High sensitivity (hs) C-reactive protein and hsTnT were measured at seven consecutive timepoints between Days 1 and 3. The area under the curve (AUC) for high-sensitivity C-reactive protein was the primary endpoint. The median AUC for high-sensitivity C-reactive protein during hospitalization was 2.1 times higher in the placebo than in the tocilizumab group (4.2 vs. 2.0 mg/L/h, P < 0.001). Also, the median AUC for hsTnT during hospitalization was 1.5 times higher in the placebo group compared with the tocilizumab group (234 vs. 159 ng/L/h, P = 0.007). The differences between the two treatment groups were observed mainly in (i) patients included ≤2 days from symptom onset and (ii) patients treated with percutaneous coronary intervention (PCI). No safety issues in the tocilizumab group were detected during 6 months of follow-up. CONCLUSION Tocilizumab attenuated the inflammatory response and primarily PCI-related TnT release in NSTEMI patients.

Effect of everolimus introduction on cardiac allograft vasculopathy--results of a randomized, multicenter trial.

Background. Everolimus reduces the progression of cardiac allograft vasculopathy (CAV) in de novo heart transplant (HTx) recipients, but the influence on established CAV is unknown. Methods. In this Nordic Certican Trial in Heart and lung Transplantation substudy, 111 maintenance HTx recipients (time post-HTx 5.8±4.3 years) randomized to everolimus+reduced calcineurin inhibitor (CNI) or standard CNI had matching (intravascular ultrasound) examinations at baseline and 12 months allowing accurate assessment of CAV progression. Results. No significant difference in CAV progression was evident between the treatment groups (P=0.30). When considering patients receiving concomitant azathioprine (AZA) therapy (n=39), CAV progression was attenuated with everolimus versus standard CNI (&Dgr;maximal intimal thickness 0.00±0.04 and 0.04±0.04 mm, &Dgr;percent atheroma volume 0.2%±3.0% and 2.6%±2.5%, and &Dgr;total atheroma volume 0.25±14.1 and 19.8±20.4 mm3, respectively [P<0.05]). When considering patients receiving mycophenolate mofetil (MMF), accelerated CAV progression occurred with everolimus versus standard CNI (&Dgr;maximal intimal thickness 0.06±0.12 vs. 0.02±0.06 mm and &Dgr;percent atheroma volume 4.0%±6.3% vs. 1.4%±3.1%, respectively; P<0.05). The levels of C-reactive protein and vascular cell adhesion molecule-1 declined significantly with AZA+everolimus, whereas MMF+everolimus patients demonstrated a significant increase in levels of C-reactive protein, vascular cell adhesion molecule-1, and von Willebrand factor. Conclusions. Conversion to everolimus and reduced CNI does not influence CAV progression among maintenance HTx recipients. However, background immunosuppressive therapy is important as AZA+everolimus patients demonstrated attenuated CAV progression and a decline in inflammatory markers, whereas the opposite pattern was seen with everolimus+MMF. The different effect of everolimus when combined with AZA versus MMF could potentially reflect hitherto unknown interactions.

Differential effect of unfractionated heparin and low molecular weight heparin on intravascular tissue factor pathway inhibitor: evidence for a difference in antithrombotic action

Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of tissue factor (TF)‐induced blood coagulation, which is increased several‐fold in post‐heparin plasma and thought to contribute significantly to the antithrombotic action of heparin. In the present study we investigated whether subcutaneous (s.c.) administration of a low molecular weight heparin (LMWH), enoxaparin, had a different effect on intravascular pools of TFPI compared with continuous i.v. infusion of unfractionated heparin (UFH). 18 healthy male volunteers were randomly assigned to continuous i.v. infusion with UFH (initially 450 U/kg/24 h, n = 6) or to s.c. treatment with LMWH once daily (enoxaparin, 1.5 mg/kg, n = 12) for 72 h. A bolus injection of 5000 IU UFH i.v. caused an 8–13‐fold increase in plasma‐free TFPI antigen (TFPI Ag), followed by a progressive decrease (81 ± 4%, P < 0.001) during the 72 h infusion with UFH. 4 h after discontinuation of the infusion, basal free TFPI Ag and heparin‐releasable TFPI were significantly decreased compared with the concentrations before the infusion (30 ± 9% and 27 ± 7%, respectively). In contrast, LMWH treatment did not reduce either basal or heparin‐releasable TFPI Ag. The changes in plasma TFPI Ag by UFH and LMWH were statistically different between groups both in pre‐ (P < 0.001) and post‐heparin (P < 0.0001) plasma. The differential effect of UFH and LMWH on intravascular pools of TFPI may contribute to the understanding of the apparent superior efficacy of LMWHs in the treatment of both arterial and venous thrombosis.

A New Sensitive Chromogenic Substrate Assay of Tissue Factor Pathway Inhibitor Type 1

The present assay is a modification of our previously published two-stage chromogenic substrate assay of tissue factor pathway inhibitor type-1 (TFPI) activity [1]. In the first stage, the reaction mixture was made with factor VIIa (FVIIa) molecules in excess of tissue factor (TF) binding sites and contained diluted plasma, recombinant FVIIa (10 nM), recombinant TF (1/400 vol/vol), bovine factor Xa (1,1 nM), I-2882(R) (100 microg/ml), and CaCl(2) (10 mM). The fibrin polymerisation inhibitor I-2882(R) was added to the reaction mixture to prevent formation of cross-linked fibrin. In the second stage, residual TF/FVIIa catalytic activity was measured by the addition of a substrate mixture that contained bovine factor X and a chromogenic substrate (S-2222(R)). Standard curves were constructed using serial dilutions (0-1%) of pooled normal plasma. The dose-response relationship for serial dilutions of plasma was linear. The intra-assay coefficient of variations (CVs) for pre- and postheparin plasma samples (i.e., normal and high TFPI levels) were 1.7% and 9.9%, respectively; the inter-assay CVs were 10.0% and 19. 7%, respectively. The effect of variation in antithrombin activity on the assay was approximately 5%. The present assay correlated fairly well with our previously published assay (r=0.82, n=100) and with a commercial TFPI activity assay (Actichrome(R) TFPI Activity Assay, American Diagnostica, Greenwich, CT, USA; r=0.90, n=100), as well as with an antigen assay for TFPI total antigen (Imubind(R), American Diagnostica; r=0,96, n=100). Altman and Bland plots revealed that our previous assay underestimated TFPI activity at high TFPI levels (i.e., postheparin TFPI samples) compared with the other methods.