Immediate unselected coronary angiography versus delayed triage in survivors of out-of-hospital cardiac arrest without ST-segment elevation: Design and rationale of the TOMAHAWK trial.

Patients experiencing out-of-hospital cardiac arrest (OHCA) without ST-segment elevation are a heterogenic group with a variety of underlying causes. Up to one-third of patients display a significant coronary lesion compatible with myocardial infarction as OHCA trigger. There are no randomized data on patient selection and timing of invasive coronary angiography after admission. METHODS AND RESULTS: The TOMAHAWK trial randomly assigns 558 patients with return of spontaneous circulation after OHCA with no obvious extracardiac origin of cardiac arrest and no ST-segment elevation/left bundle-branch block on postresuscitation electrocardiogram to either immediate coronary angiography or initial intensive care assessment with delayed/selective angiography in a 1:1 ratio. The primary end point is 30-day all-cause mortality. Secondary analyses will be performed with respect to initial rhythm, electrocardiographic patterns, myocardial infarction as underlying cause, neurological outcome, as well as clinical and laboratory markers. Clinical follow-up will be performed at 6 and 12 months. Safety end points include bleeding and stroke. CONCLUSION: The TOMAHAWK trial will address the unresolved issue of timing and general indication of angiography after OHCA without ST-segment elevation.

Prolonged clopidogrel application reduces tissue factor expression after percutaneous coronary intervention in the porcine model.

BACKGROUND: Late thrombotic events are important complications associated with intracoronary brachytherapy (ICBT) using ionizing radiation (IR) or with antiproliferative treatment modalities such as drug-eluting stents (DES). The mechanism mediating these thrombotic events is not well understood. This study assessed the effect of prolonged clopidogrel treatment on tissue factor (TF) expression in coronary arteries and on the circulating TF level after percutaneous transluminal coronary angioplasty /ICBT in a porcine coronary model. METHODS: Pigs were treated with aspirin plus a 300 mg loading dose of clopidogrel one day before percutaneous coronary intervention (PCI), followed by a daily dose of clopidogrel and aspirin. During PCI one of the two balloon-injured arteries was treated by brachytherapy. Animals were sacrificed at different time points. The pigs, which were sacrificed 3 months post-PCI, were divided into two groups (Group I: clopidogrel for 3 months; Group II: clopidogrel for 1 month). Plasma TF was measured by enzyme-linked immunosorbent assay in blood samples taken from all pigs before and immediately after intervention and before sacrifice. Morphometric analysis was performed on digitalized images employing the software LUCIA G for TF staining. Vascular TF expression levels were assessed by quantitative real-time polymerase chain reaction. RESULTS: Prolonged clopidogrel application significantly reduced coronary TF at the protein (Group I vs. II, 8.975 ± 3.947% vs. 26.44 ± 5.375%, P = .007) and mRNA level [Group I vs. II, (0.3501 ± 0.0519) × 10(-3) vs. (0.7073 ± 0.0436) × 10(-3), P<.0005]. Circulating TF protein tended to be lower after 3 months than after 1 month clopidogrel treatment post-PCI (Group I vs. Group II, 488.3 ± 35.37 pg/ml vs. 572.3 ± 39.9 pg/ml, P = .130). CONCLUSIONS: Prolonged clopidogrel treatment reduced coronary TF expression and tended to reduce the blood TF level post-PCI, thus possibly modulating the risk of late thrombosis.

Complex porcine model of atherosclerosis: induction of early coronary lesions after long-term hyperlipidemia without sustained hyperglycemia.

BACKGROUND: The incidence of coronary artery disease (CAD) is still increasing in industrialized countries and it is even higher in diabetic patients. For experimental studies investigating the pathophysiology of CAD, the use of an animal model comparable with the pathological situation in patients is crucial. OBJECTIVE: To develop a model of advanced coronary atherosclerosis with induction of hyperlipidemia and hyperglycemia in domestic pigs. METHODS: Six pigs were fed a standard pig chow (controls), two were fed a 2% cholesterol and 17% coconut fat diet (Chol group), and two pigs received a 4% cholesterol and 17% coconut fat diet combined with streptozotocin (STZ) injections to induce diabetes (High Chol+STZ group). Serum lipid and plasma glucose values were analyzed, and histochemical staining for morphometric analysis and immunohistochemistry were performed. RESULTS: Pigs on the hyperlipidemic diet had elevated mean (+/- SD) serum lipid levels (total cholesterol 5.05+/-1.45 mmol/L [Chol] and 5.03+/-2.41 mmol/L [High Chol+STZ] versus 2.09+/-0.23 mmol/L [controls]). Histopathological evaluation revealed an initial stage of coronary atherosclerosis. None of the STZ-treated pigs showed a sustained elevation of plasma glucose (mean glucose before STZ injection was 5.11+/-0.94 mmol/L and thereafter was 6.03+/-2.39 mmol/L) or a decline in pancreatic beta cells. CONCLUSIONS: The current data suggest that the domestic porcine model is not suitable to create severe CAD using an atherogenic diet in combination with STZ injections for experimental interventional vascular research. This may be due to different STZ sensitivities among species. However, hyperlipidemia induced early pathological lesions in coronary arteries resembling initial stages of atherosclerosis without severe luminal narrowing.

Prehospital versus periprocedural abciximab in ST-elevation myocardial infarction treated by percutaneous coronary intervention.

OBJECTIVE: To investigate the potential benefit of an earliest possible out-of-hospital start of abciximab (ReoPro) therapy in ST-elevation myocardial infarction (STEMI; Lilly, Bad Homburg, Germany) and planned primary percutaneous intervention compared with periprocedural abciximab treatment on reperfusion and clinical outcome. METHODS: Randomization of one hundred and one patients with STEMI to prehospital or periprocedural abciximab treatment. Evaluation of thrombolysis in myocardial infarction (TIMI) flow, ST-segment resolution, myocardial blush grade, and maximal creatine kinase release before and after as well as clinical follow-up until 6 months after the index event. RESULTS: Prehospital abciximab (group 1) was initiated a median of 101 min (37-165 min) earlier compared with periprocedural treatment (group 2). Initial TIMI 3 flow (24 vs. 15%, P=NS), ST-segment resolution before percutaneous coronary intervention (PCI) (<30%: 33 vs. 46%, P=NS; >70%: 38 vs. 33%, P=NS), post-PCI myocardial blush grade 2 and 3 (72 vs. 75%, P=NS), maximal cardiac enzyme release (creatinine kinase MB median 77 U/l; range 33-137 vs. 74 U/l; range 39-143 U/l, P=NS), and 6 months follow-up (recurrent myocardial infarction or repeat coronary intervention, and PCI, need for coronary bypass surgery) did not differ significantly between both treatment groups. CONCLUSION: Prehospital intravenous administration of abciximab, although safe and feasible in a trained surrounding, does not add angiographic or clinical benefit to patients with STEMI.

Achievement of guideline-defined treatment goals in primary care: the German Coronary Risk Management (CoRiMa) study.

AIMS: The success in achieving treatment goals for cardiovascular risk factors in primary care is largely unknown. Therefore, the goals of this study were (i) to assess whether routinely collected practice data can be used to evaluate treatment in primary care, (ii) to compare current treatment with goals of published guidelines, and (iii) to calculate future risk for cardiovascular events using these real-life data. METHODS AND RESULTS: In 110 physician offices in Germany, data from the patient management systems of all patients seen between January 1998 and June 2005 were extracted and analysed (715 644) with current guidelines used for reference. Of those patents, 284 096 (40% of all patients analysed) had one of the following diseases: 157 101 (55% of 284 096) had hypertension, 83 005 (29%) diabetes, 64 205 (23%) coronary artery disease (CAD), 174 787 (62%) hyperlipidaemia, and 136 360 (48%) had more than one of the listed diagnoses. During the last visit, treatment goals were achieved for total and LDL cholesterol in 9 and 29%, respectively, for blood pressure in 28%, and for HbA1c in 36%. Low achievement of treatment goals was also seen in patients with CAD or diabetes. Using the Framingham risk model and the SCORE Deutschland risk charts, 20 and 22% of patients had a high 10-year risk for a primary cardiovascular event and a fatal cardiovascular event, respectively. Achieving treatment goals for all risk factors would significantly reduce the number of high-risk patients. CONCLUSION: (i) Routinely collected practice data can be used to evaluate quality of care; (ii) 40% of patients in primary care have cardiovascular disease or diabetes; (iii) even in high-risk patients, the majority does not achieve treatment goals; and (iv) achieving the treatment goals would reduce the proportion of high-risk patients from 20 to <5%.

Prolonged application of clopidogrel reduces inflammation after percutaneous coronary intervention in the porcine model.

OBJECTIVE: We determined the effect of prolonged treatment with clopidogrel on C-reactive protein (CRP) concentrations and blood thrombogenicity after percutaneous transluminal coronary angioplasty followed by intracoronary brachytherapy in the porcine model. ANIMAL MODEL: All 48 pigs received antiplatelet therapy, including aspirin (325 mg, daily) and clopidogrel (300 mg, loading dose) 1 day before PCI, followed by a daily dose of clopidogrel (75 mg/day) in addition to aspirin. During PCI, one of two balloon-injured arteries was randomly assigned to receive immediate radiation treatment. Animals were sacrificed after 24 h, 1 month, and 3 months post-PCI. The pigs, which were sacrificed 3 months post-PCI, were divided into two groups. The first group received clopidogrel in addition to aspirin for 3 months, and the second group received clopidogrel in addition to aspirin for only 1 month after PCI and then aspirin alone. METHODS: Blood was taken from all pigs before intervention, immediately after intervention, and before sacrifice. Serum CRP was measured by enzyme-linked immunosorbent assay. To analyze the procoagulant effects of PCI on blood thrombogenicity, a one-stage clotting assay was performed. RESULTS: Clopidogrel treatment for 3 months reduced CRP levels more than did clopidogrel therapy for 1 month only at 3 months post-PCI (27.9+/-3.9 vs. 56.6+/-11.3 microg/ml; P=.019). Baseline CRP levels were found to be 50.4+/-4.8 microg/ml. Plasma clotting was not affected by prolonged clopidogrel therapy (322.8+/-59.3 s vs. 295.2+/-52.5 s; P=ns). CONCLUSIONS: Prolonged treatment with clopidogrel reduced CRP levels post-PCI.

Effect of ionizing radiation on cellular procoagulability and co-ordinated gene alterations.

BACKGROUND AND OBJECTIVES: Ionizing radiation (IR) is associated with thrombotic vascular occlusion predicting a poor clinical outcome. Our study examined whether IR induced tissue factor (TF) expression and procoagulability. We further investigated coordinated gene alterations associated with TF upregulation in the myelomonocytic leukemia THP-1 cells. DESIGN AND METHODS: TF expression was determined by quantitative Reverse Transcriptase (TaqMan) PCR, TF ELISA and TF activity by a two stage chromogenic assay in the time course of days 1, 3, 7, 10, and 17 post IR. To detect IR-induced alterations in gene expression, Affymetrix HG U133 Plus 2.0 microarrays were used. RESULTS IR induced a significant increase in TF/GAPDH mRNA ratios and cellular TF protein on days 3 and 7 post IR (20 Gy [p>or=0.01] and 40 Gy [p or=0.001] vs. control respectively), suggesting IR immediately alters the cellular thrombogenicity. TF upregulation post IR was confirmed in PBMNCs. Gene expression profiling showed IR increased the expression of inflammatory and apoptosis-related pathways known to be involved in the regulation of TF expression. INTERPRETATION AND CONCLUSIONS: TF upregulation together with inflammation and apoptosis may increase the thrombogenicity of tissues. The demonstrated upregulation of TF might play a pivotal role in radiation associated thrombosis.

Mechanisms of late lumen loss after antiproliferative percutaneous coronary intervention using beta-irradiation in a porcine model of restenosis.

BACKGROUND: The short-term results for the prevention of coronary restenosis after intravascular brachytherapy (IVBT) and use of drug-eluting stents (DESs) are excellent. The long-term results either lack or present with late complications (e.g., late thrombosis and late catch-up phenomenon leading to late restenosis even years after the initial procedure). Both IVBT and DESs mediate their potent antirestenotic effects via a cytostatic mechanism, but the cardiovascular pathology at late time points after the use of these antiproliferative therapies is incompletely understood. This study investigated the long-term effects of antiproliferative beta-irradiation in a clinically relevant porcine coronary model to address the pathophysiology of late coronary restenosis after antiproliferative vascular interventions. METHODS: We performed percutaneous transluminal coronary angioplasty (PTCA) in two major coronary arteries in 12 domestic crossbred pigs. One of the two balloon-injured segments was randomly assigned to receive immediate beta-irradiation (PTCA+IVBT group) using a noncentered delivery catheter (20 Gy; Novoste Beta-Cath System, Novoste, Norcross, GA, USA). The animals were sacrificed after 14 days (n=6) or 3 months (n=6). RESULTS: The luminal area in the PTCA+IVBT group decreased significantly 3 months after the intervention as compared with that in the PTCA group (PTCA 3.45+/-0.46 mm2 vs. PTCA+IVBT 1.22+/-0.26 mm2; P=.0017). This lumen loss was primarily due to shrinkage of the external elastic lamina area (negative arterial remodeling; PTCA 5.22+/-0.27 mm2 vs. PTCA+IVBT 3.42+/-0.45 mm2; P=.0064), which was accompanied by an increase in the adventitial area (PTCA 3.07+/-0.2 mm2 vs. PTCA+IVBT 5.41+/-0.5 mm2; P=.0049). CONCLUSIONS: The application of antiproliferative radiation in a porcine coronary model caused an early beneficial effect (reduction of intimal-medial lesion and luminal gain) that was followed by a late lumen loss primarily due to negative arterial remodeling. This mechanism may in part help us understand the pathophysiology of late adverse events occurring after IVBT.

Nf-kappab and AP-1 activation is associated with late lumen loss after porcine coronary angioplasty and antiproliferative beta-irradiation.

OBJECTIVE: Despite the success of antiproliferative therapies, restenosis remains a common problem after percutaneous transluminal coronary angioplasty (PTCA). Longer-term clinical results of brachytherapy (intracoronary radiation), the lack of long-term clinical results after implantation of drug eluting stents, and the occurrence of late thrombosis after both procedures leave room for skepticism. Neointimal proliferation is not substantially inhibited at late time points after brachytherapy, and late lumen loss with a "catch-up" proliferation can occur. We hypothesized that the transcription factors nuclear factor-{kappa}B (NF-kappaB) and activator protein-1 (AP-1) are involved in these processes. We addressed the role of these mediators in a porcine model of coronary restenosis. METHODS: Thirty-nine pigs underwent PTCA in two major coronary arteries. One of the two balloon-injured arteries was randomly assigned to receive immediate 20 Gy beta-irradiation (Brachy group) using a noncentered source train ((90)Sr/Y Beta-Cath, Novoste). Animals were sacrificed after 1 day, 14 days, or 28 days. Proliferating cells were labeled prior to euthanasia. RESULTS: At late time points, lumen area was significantly smaller and the inflammatory response was more pronounced in the Brachy group than in the PTCA group. These findings coincided with sustained activation of MMP-9 and transcription factors like NF-kappaB and AP-1. Initially, cell proliferation was reduced in the Brachy group; however, at late time points, differences between the two treatment groups were no longer significant. CONCLUSIONS: Brachytherapy initially inhibits cell proliferation; however, cellular and molecular inflammatory processes (e.g. activation of NF-kappaB) are enhanced within the arterial wall. This proinflammatory side effect may be responsible for the observed delayed proliferation and the resulting lumen loss.

Ionizing radiation induces upregulation of cellular procoagulability and tissue factor expression in human peripheral blood mononuclear cells.

INTRODUCTION: The therapeutic application of ionizing radiation is associated with thrombotic events, but the exact underlying molecular mechanisms are still unclear. Tissue factor (TF), the primary initiator of blood coagulation, is essentially involved in the pathophysiology of thrombosis. Circulating monocytes have been identified to upregulate TF under inflammatory conditions and, thereby, enhance blood thrombogenicity. The study examines the effect of irradiation on the cellular procoagulability and TF protein expression of human peripheral blood mononuclear cells (PBMNCs) in a time period of 7 days. MATERIALS AND METHODS: Human PBMNCs were irradiated with 20 Gy. Procoagulability of PBMNCs, released microparticles and microparticle-free cell supernatant was analyzed by a chromogenic assay and TF protein expression quantified by TF ELISA. To determine whether irradiated PBMNCs and shed microparticles initiate plasma clotting, a one stage clotting assay was performed. RESULTS: We found a significant increase of PBMNC-associated procoagulant activity over a time period of 7 days post irradiation. Moreover, 3 days post irradiation PBMNCs initiated the plasma clotting faster than non-irradiated cells. An enhanced cellular TF protein concentration was persistently observed throughout the investigated time up to 7 days post irradiation. Microparticle-associated TF activity significantly increased 3 days post irradiation compared with the non-irradiated controls. PBMNC-derived microparticles post irradiation also initiated the plasma clotting faster than microparticles derived from controls. CONCLUSIONS: The results show irradiation to induce TF expression and to increase procoagulability of PBMNCs and cell-derived microparticles. This could be a possible mechanism by which ionizing radiation enhances blood thrombogenicity.

Antioxidative treatment inhibits the release of thrombogenic tissue factor from irradiation- and cytokine-induced endothelial cells.

OBJECTIVES: The aim of this study was to investigate the effect of the antioxidants pyrrolidine dithiocarbamate (PDTC) and N-acetylcysteine (NAC) on the ionizing radiation (IR)- and tumor necrosis factor-alpha (TNF-alpha) induced tissue factor (TF) expression and its release from human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs were irradiated with a single dose of either 5 Gy or 10 Gy and stimulated with TNF-alpha (10 ng/mL) in the presence or absence of PDTC and NAC, respectively. Quantitative real-time PCR, ELISA, and TF activity measurements were performed, including TF activity in the supernatant. Apoptosis was detected by flow cytometric active caspase-3 measurement and formation of reactive oxygen species (ROS) by chemiluminescence. RESULTS: We demonstrated a thus far uninvestigated persistent induction of TF expression in HUVECs after treatment with IR and TNF-alpha. Combined stimulation with IR and TNF-alpha led to an immense shedding of microparticle-associated TF which was positively correlated with apoptosis and ROS formation. Antioxidative pre-treatment reduced not only apoptosis and ROS formation, but also the release of thrombogenic microparticles. CONCLUSIONS: Antioxidative treatment inhibited apoptosis and shedding of microparticles, thereby reducing thrombogenicity. Thus, antioxidants may help to prevent late thrombosis after antiproliferative treatment when used in combination with anticoagulants.

Adventitial VEGF165 gene transfer prevents lumen loss through induction of positive arterial remodeling after PTCA in porcine coronary arteries.

Negative arterial remodeling still plays an important role in the pathogenesis of coronary restenosis even in the era of interventional stenting (e.g. arterial narrowing occurs proximal and distal of a stented segment). Previous studies suggest that increased angiogenesis and inhibited regression of injury-induced adventitial microvessels prevents negative remodeling. We have examined the effect of local vascular endothelial growth factor (VEGF(165)) gene transfer on adventitial microvessel angiogenesis/regression and arterial remodeling after coronary angioplasty. Twenty pigs underwent angioplasty, each one in two major coronary arteries, followed by plasmid liposome gene transfer with either VEGF(165) or control gene LacZ (50 microg DNA with 50 microg of Lipofectine) into the (peri)adventitial space using a needle injection catheter. Arteries were examined at days 1, 7, 14, and 28. Local delivery of VEGF(165) gene into the outer compartments of balloon-injured porcine coronary arteries reduced lumen area loss due to distinct positive remodeling (arterial enlargement). Prevention of adventitial microvessel regression, enhanced adventitial elastin accumulation, reduced adventitial myofibroblast numbers, and a pronounced adventitial inflammatory response considered as a part of arterial healing seem to be the main VEGF-mediated mechanisms indicating the therapeutic potential of VEGF for restenosis prevention.

Effect of adventitial VEGF(165) gene transfer on vascular thickening after coronary artery balloon injury.

OBJECTIVE: Experimental studies have provided evidence that neovascularization is an important feature of plaque growth, and angiogenic gene therapy may, therefore, increase plaque growth. This study examined the effect of local (peri)adventitial vascular endothelial growth factor165 (VEGF) gene transfer on vascular thickening after coronary balloon injury. METHODS: Two coronary arteries of 15 pigs were subjected to balloon injury followed by either (peri)adventitial VEGF165 or beta-galactosidase (LacZ) plasmid/liposome-mediated gene transfer via needle injection catheter. At days 3, 14 and 28, histologic sections of coronary arteries were analyzed. RESULTS: Transferred VEGF165 gene and increased adventitial neovascularization were detected in coronary arteries after balloon injury and VEGF injection. The mean intima+media (I+M) area increased after coronary balloon injury and VEGF (1.13+/-0.17 and 2.54+/-0.52 mm(2)) or LacZ (1.37+/-0.19 and 2.96+/-0.41 mm(2)) gene transfer, with no significant difference between both groups at 3 and 28 days, respectively. No significant difference in I+M neovascularization was observed at day 28 between the treatment groups (microvessel area density 0.24+/-0.08% with VEGF and 0.26+/-0.14% with LacZ, respectively). I+M endothelial cell proliferation index ranged from 7% to 22% (VEGF) and 18% to 24% (LacZ). CONCLUSIONS: Catheter-mediated (peri)adventitial VEGF165 gene transfer induces adventitial neovascularization but not an increase of vascular thickening/I+M growth and vascularization in a porcine model of coronary artery injury.