Are myocardial infarction and venous thromboembolism associated? Population-based case–control and cohort studies

Introduction

Because the association of myocardial infarction (MI) and venous thromboembolism (VTE) is uncertain, we tested MI as a VTE risk factor and VTE as a predictor of MI.

Materials and Methods

Using Rochester Epidemiology Project resources, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE over the 13-year period, 1988–2000 (n = 1311), one to two resident controls per VTE case (n = 1511), and all residents with incident MI over the 31-year period, 1979–2010. For VTE cases and controls, we reviewed their complete medical records in the community for VTE and MI risk factors. Using conditional logistic regression we tested MI as a potential VTE risk factor, both unadjusted and after adjusting for VTE risk factors. We also followed VTE cases and controls without prior MI forward in time for incident MI through 12/31/2010, and using Cox proportional hazards modeling, tested VTE as a predictor of MI, both unadjusted and after adjusting for MI risk factors.

Results

The number (%) of MI prior to VTE among cases and controls were 75 (5.7) and 51 (3.4), respectively, and the number (%) of MI after VTE among cases and controls were 58 (4.4) and 77 (5.1), respectively. In univariate analyses, MI was significantly associated with VTE but not after adjusting for VTE risk factors. In both univariate and multivariate analyses, VTE (overall or idiopathic) was not a predictor of MI.

Conclusions

MI is not an independent risk factor for VTE, and VTE is not a predictor of MI.     

Low prevalence of heparin-induced thrombocytopenia after cardiac surgery in Thai patients

Introduction

Heparin induced-thrombocytopenia (HIT) has been well recognized in Western countries. However, there are no data in the Thai population. We therefore investigated the prevalence of anti-platelet factor 4 (PF4)/heparin antibodies, HIT, and its thrombotic complications in Thai patients undergoing cardiac surgery using unfractionated heparin.

Materials and methods

Seventy-three consecutive patients were prospectively enrolled in this study. Blood samples before operation and week 1, week 2, and week 3 after operation were collected from each patient for HIT antibody screening by enzyme-linked immunosorbent assay using IgG antibody specific to the PF4/heparin complex. Positive samples were further analyzed by ¹⁴C-serotonin release assay. Complete blood count was performed daily during the first week, then weekly for 3 weeks.

Results

No patient had detectable anti-PF4/heparin antibodies at baseline. Five patients sero-converted during the course of the study for anti-PF4/heparin IgG: 3 (4.1%) at week 1, 4 (5.5%) at week 2, and 5 (6.8%) at week 3 after surgery. However, none of these patients had anti-PF4/heparin antibodies that resulted in ¹⁴C-serotonin release to be considered clinically significant antibodies. Post-operative thrombocytopenia after the operation was found in 35 patients (47.9%), but was not considered to be caused by HIT. Thromboembolic events occurred in 3 patients (4.1%) during follow up; however, none of these patients had positive PF4/heparin antibody tests.

Conclusions

Our study represents the first study to examine Thai patients exposed to heparin in the context of cardiac surgery. We found a lower prevalence of positive anti-PF4/heparin antibodies and clinical HIT than previously published studies.     

Alpha-1 proteinase inhibitor M358R reduces thrombin generation when displayed on the surface of cells expressing tissue factor

The M358R variant of alpha-1-proteinase inhibitor (API) is a potent soluble inhibitor of thrombin. Previously we engineered AR-API M358R, a membrane-bound form of this protein and showed that it inhibited exogenous thrombin when expressed on transfected cells lacking tissue factor (TF). To determine the suitability of AR-API M358R for gene transfer to vascular cells to limit thrombogenicity, we tested the ability of AR-API M358R to inhibit endogenous thrombin generated in plasma via co-expression co-expressing it on the surface of cells expressing TF. Transfected AR-API M358R formed inhibitory complexes with thrombin following exposure of recalcified, defibrinated plasma to TF on T24/83 cells, but discontinuously monitored thrombin generation was unaffected. Similarly, AR-API M358R expression did not reduce continuously monitored thrombin generation by T24/83 cell suspensions exposed to recalcified normal plasma in a Thrombogram-Thrombinoscope-type thrombin generation assay (TGA); in contrast, 1 μM hirudin variant 3 or soluble API M358R abolished thrombin generation. Gene transfer of TF to HEK 293 conferred the ability to support TF-dependent thrombin generation on HEK 293 cells. Co-transfection of HEK 293 cells with a 9:1 excess of DNA encoding AR-API M358R to that encoding TF reduced peak thrombin generation approximately 3-fold compared to controls. These in vitro results suggest that surface display of API M358R inhibits thrombin generation when the tethered serpin is expressed in excess of TF, and suggest its potential to limit thrombosis in appropriate vascular beds in animal models.     

Hemorheological changes with strontium ranelate treatment do not seem to be related to its claimed prothrombotic effects

Strontium ranelate is claimed to be related with increased risk of thromboembolic events. No explanation of this increased incidence of thromboembolism has been identified. However, growing evidence has clearly demonstrated the involvement of blood rheology in any thrombotic process. The aim of this study was to assess hemorheological changes with strontium ranelate treatment in elderly women with osteoporosis. This study was designed in a prospective manner. Twenty-two elderly women diagnosed with osteoporosis were included. During a 2-month treatment period, participants received strontium ranelate 2 g/day. Hemorheological parameters including erythrocyte deformability, erythrocyte aggregation and plasma viscosity were measured before and after 2 months therapy with strontium ranelate. The median age of the patients was 70.0 (range = 65-80) years. After 60 days of treatment, there was no statistically significant change in hemorheological parameters. None of the subjects developed clinical venous thromboembolic event (VTE) during the 2-month period of strontium ranelate treatment. Our study demonstrated that in elderly women, treatment of osteoporosis with strontium ranelate did not change hemorheological parameters over 2 months of time. However, its long-term effects on hemorheologic parameters should be evaluated further with a larger sample.     

Thrombotic complications associated with stem cell transplantation

Thrombotic complications are common in stem cell transplantation (SCT) recipients and endothelial cell injury is a dominant contributing factor to the hemostatic impairments. Endothelial cells line the vascular bed and each vascular bed has a unique structural and functional properties. Therefore, understanding of these properties may hold important clues to site-specific diagnostics and therapeutics. The two most common thrombotic manifestations related to SCT, veno-occlusive disease (VOD) and thrombotic microangiopathy (TMA), are characterized by small vessel thrombosis in the microcirculation. In diffuse alveolar hemorrhage (DAH), although the clinical presentation is hemorrhagic, autopsy findings and mice experiments imply a thrombotic etiology. In the present review, the pathogenesis and treatment options of these three microcirculation thromboses are discussed.     

Recurrent venous thromboembolism while on anticoagulant therapy

There has been immense progress in the management of venous thromboembolism in recent years with increased awareness and adequate thromboprophylaxis proving successful in reducing the morbidity and mortality associated with this condition. One of the commonest complications of an initial venous thrombosis is the development of recurrent thrombosis. Unlike in the case of the first clot, the diagnosis and management of the recurrent episode remain a difficult issue. Even more challenging is the clinical situation where a new thrombus develops while the patient is being treated with anticoagulant medication for a previous clot. The clinical approach and management of these patients are complex, and require understanding of the differences in thrombus development in the different clinical circumstances.     

血栓抽吸前后冠状动脉内注射替罗非班在急性ST段抬高型心肌梗死患者中的应用

目的评价急性心肌梗死患者行急诊PCI时在应用血栓抽吸导管进行血栓抽吸前后冠状动脉内注射替罗非班对患者的心肌再灌注、心功能以及主要心脏事件的影响。方法取2009年9月至2011年11月在常平医院行急诊PCI治疗的急性ST段抬高型心肌梗死153例,按数字表法随机分为两组,其中一组在造影术后,血栓抽吸前立即冠状动脉内注射替罗非班15ml,另一组在血栓抽吸术后冠状动脉内注射替罗非班15ml,评价PCI术后两组间造影结果以及左室射血分数、MACE的情况等等。结果在血栓抽吸前冠状动脉内注射替罗非班组MBG2、3级的比例为85.0%,而在血栓抽吸后冠状动脉内注射替罗非班组的比例为67.1%,差异具有统计学意义。出院前LVEF值分别为71.5±10.0和61.5±11.0,差异具有统计学意义。而冠状动脉内TIMI3级血流、CTFC帧数、以及ST段回落率在两组间的差异没有统计学意义。结论在急性ST段抬高型心肌梗死患者行PCI时,如果患者血栓负荷过重,在支架置入术前先行冠状动脉内替罗非班注射,然后再进行血栓抽吸可以得到更好的心肌再灌注,并且对LVEF的改善有益。     

心血管疾病戒烟干预中国专家共识

吸烟是心血管疾病的独立危险因素,并且也是患者唯一能够自我控制的致病因素。许多心血管医生已经认识到吸烟的危害和戒烟干预的重要性,但尚缺乏相应的戒烟知识和戒烟技巧。本共识通过全面总结吸烟的危害和戒烟的益处,     

急性混合型下肢深静脉血栓综合介入治疗与系统溶栓疗效的比较

目的：比较综合介入治疗与系统溶栓治疗对急性混合型下肢深静脉血栓（LEDVT）的疗效。方法：回顾分析12年间收治的229例急性混合型LEDVT患者的临床资料。122例采用血栓碎吸、溶栓等综合介入治疗（A组）,其中合并髂静脉狭窄或闭塞53例,采取腔内血管成形术（PTA）和支架植入辅助处理,术后辅以小剂量尿激酶溶栓、肝素抗凝治疗;另107例（B组）行尿激酶,肝素抗凝等系统溶栓治疗。结果：平均住院天数A组（6.2±2.2）d,B组（10.5±2.4）d;2周后复查,A,B两组的治愈率和有效率分别为40.98%,14.02%和96.72%,77.57%,差异均有统计学意义（均P<0.05）。随访12~85个月,患肢膝下15 cm处周径差A组为（0.53±0.42）cm,B组为（1.42±1.35）cm;水肿、色素沉着、溃疡等后遗症发生率A组分别23.15%,9.26%和0,B组分别为50.51%,80.81%和9.09%,A组静脉通畅率为81.48%,静脉瓣膜功能正常率为57.41%,B组为65.66%和15.15%,差异均有统计学意义（P<0.05）。结论：综合介入治疗对急性混合型LEDVT的近期、中远期疗效均优于系统溶栓,尤其在保护静脉瓣膜功能方面明显优于系统溶栓。