Eastern Association for the Surgery of Trauma Multicenter Trial: Comparison of pre-injury antithrombotic use and reversal strategies among severe traumatic brain injury patients

BACKGROUND

Trauma teams are often faced with patients on antithrombotic (AT) drugs, which is challenging when bleeding occurs. We sought to compare the effects of different AT medications on head injury severity and hypothesized that AT reversal would not improve mortality in severe traumatic brain injury (TBI) patients.

METHODS

An Eastern Association for the Surgery of Trauma-sponsored prospective, multicentered, observational study of 15 trauma centers was performed. Patient demographics, injury burden, comorbidities, AT agents, and reversal attempts were collected. Outcomes of interest were head injury severity and in-hospital mortality.

RESULTS

Analysis was performed on 2,793 patients. The majority of patients were on aspirin (acetylsalicylic acid [ASA], 46.1%). Patients on a platelet chemoreceptor blocker (P2Y12) had the highest mean Injury Severity Score (9.1 ± 8.1). Patients taking P2Y12 inhibitors ± ASA, and ASA-warfarin had the highest head Abbreviated Injury Scale (AIS) mean (1.2 ± 1.6). On risk-adjusted analysis, warfarin-ASA was associated with a higher head AIS (odds ratio [OR], 2.43; 95% confidence interval [CI], 1.34-4.42) after controlling for Injury Severity Score, Charlson Comorbidity Index, initial Glasgow Coma Scale score, and initial systolic blood pressure. Among patients with severe TBI (head AIS score, ≥3) on antiplatelet therapy, reversal with desmopressin (DDAVP) and/or platelet transfusion did not improve survival (82.9% reversal vs. 90.4% none, p = 0.30). In severe TBI patients taking Xa inhibitors who received prothrombin complex concentrate, survival was not improved (84.6% reversal vs. 84.6% none, p = 0.68). With risk adjustment as described previously, mortality was not improved with reversal attempts (antiplatelet agents: OR 0.83; 85% CI, 0.12-5.9 [p = 0.85]; Xa inhibitors: OR, 0.76; 95% CI, 0.12-4.64; p = 0.77).

CONCLUSION

Reversal attempts appear to confer no mortality benefit in severe TBI patients on antiplatelet agents or Xa inhibitors. Combination therapy was associated with severity of head injury among patients taking preinjury AT therapy, with ASA-warfarin possessing the greatest risk.

LEVEL OF EVIDENCE

Prognostic, level II.

[Antithrombotic therapy in patients with peripheral artery diseases]

Complications of cardiovascular diseases whose substrate is atherothrombosis continue to occupy leading positions in the structure of mortality worldwide. Peripheral artery diseases (PAD), in particular, are characterized by an especially unfavourable life prognosis for patients with cardiovascular diseases. In order to decrease the risks of ischaemic complications in patients with PAD, various approaches to antithrombotic therapy have over the last two decades been studied, with the resulting standard of therapy continuing to be acetylsalicylic acid. Even more difficult today is the task of selecting antithrombotic therapy in patients having endured revascularization.

[Antithrombotic therapy after bypass grafting below the inguinal ligament]

The importance of antithrombotic therapy following reconstructive operations on arteries below the inguinal ligament is beyond question. The pharmaceutical market offers a wide variety of antiaggregant and anticoagulant agents, with many studies (including randomised and multicenter ones) performed worldwide on the problem of choosing optimal antithrombotic therapy in the postoperative period after arterial reconstructions. Nevertheless, the problem of selecting adequate antithrombotic therapy after shunting operations remains undetermined. Presented in the article is a review of foreign studies on the problem concerned. This is followed by discussing the results of many large international studies, including such trials as the BOA and CASPAR. Based on the findings obtained in these studies, Cochrane reviews, European and American guidelines, the authors express their opinion on the algorithms of choosing an appropriate variant of antithrombotic therapy during the postoperative period in patients after arterial reconstructions below the inguinal ligament.

[Thrombolytic therapy for submassive/ intermediate risk Pulmonary Embolism Evidence and suggestions after PEITHO trial]

Therapy for submassive pulmonary embolism (intermediate risk), remains controversial. New evidence has appeared that may help us in the process of decision making. We review the relevant literature, outline prognostic factors, and discuss current recommendations and controversies regarding the available alternatives such as systemic and catheter-directed thrombolytic use.

HDL particle subpopulations: Focus on biological function

Low levels of high-density lipoprotein-cholesterol (HDL-C) constitute an independent biomarker of cardiovascular morbi-mortality. However, recent advances have drastically modified the classical and limited view of HDL as a carrier of 'good cholesterol', and have revealed unexpected levels of complexity in the circulating HDL particle pool. HDL particles are indeed highly heterogeneous in structure, intravascular metabolism and biological activity. This review describes recent progress in our understanding of HDL subpopulations and their biological activities, and focuses on relationships between the structural, compositional and functional heterogeneity of HDL particles.

[Current management of antithrombotic treatment in patients with non valvular atrial fibrillation and prior history of stroke or transient ischemic attack]

Atrial fibrillation is the most frequent arrhythmia seen in clinical practice and is one of the most important risk factors for suffering a stroke. Strokes associated to atrial fibrillation are more severe, present higher mortality and disability rates, and there is a greater risk of recurrence. Consequently, both primary and secondary prevention of stroke associated to atrial fibrillation by means of suitable antithrombotic treatment is clearly essential in order to lower this risk. Chronic oral anticoagulants are the cornerstone of antithrombotic treatment in patients with non-valvular atrial fibrillation, especially in those who have already had a stroke. Vitamin K antagonists have traditionally been used for this purpose. Yet, these drugs have several important disadvantages (narrow therapeutic window, unpredictable response, numerous interactions with drugs and foods, as well as starting and finishing their action slowly), which limit their use in clinical practice. The new oral anticoagulants not only overcome these disadvantages but also have proved to be at least as effective as warfarin in the prevention of strokes and systemic embolism in patients with non-valvular atrial fibrillation. Additionally, they have been shown to have a better safety profile, especially with an important drop in the risk of intracranial haemorrhage, regardless of the antecedents of stroke or transient ischaemic attack, which makes them first-choice drugs in the treatment of these patients.

Advances in revascularization for acute ischemic stroke treatment

Intravenous thrombolysis with recombinant tissue plasminogen activator is the established treatment for acute ischemic stroke patients presenting within 3 h after stroke onset. In a significant number of patients, however, intravenous thrombolysis with recombinant tissue plasminogen activator remains ineffective. New thrombolytic agents, such as reteplase, tenecteplase or desmoteplase, offer pharmacokinetic and dynamic advantages over recombinant tissue plasminogen activator and have been or are currently being tested for safety and efficacy in clinical trials. Endovascular revascularization is an evolving treatment option enabling mechanical clot disruption or extraction in combination with thrombolysis. Several new endovascular devices have been successfully tested for safety in acute ischemic stroke patients and are now being tested for efficacy in larger clinical trials. Continued innovation and refinement of endovascular technology and techniques is expected to increase technical success with a minimal procedure-related morbidity in the treatment of acute ischemic stroke.

[What physicians think and know about antithrombotic therapy in atrial fibrillation]

We conducted an anonymous survey among 382 physicians (58% internists, 42% cardiologists) in order to obtain information on their opinion on various aspects of antithrombotic therapy in atrial fibrillation. The survey revealed low level of awareness about algorithms of stratification of risks of stroke, systemic embolism, and bleeding. Reported rates of clinical use of recommended antithrombotic agents were: warfarin--30, aspirin monotherapy--19, dabigatran--10, rivaroxaban--8, and combination of aspirin and clopidogrel--8%. Rate of use of drugs without sufficient evidence base in AF was 25%. When asked to designate antithrombotic drug of choice 85% of physicians indicated warfarin and 12%--novel anticoagulants (NOAC). The following factors were considered as limiting wide application of NOAC: high cost (59%), lack of data on these drugs (14%), and impossibility to control safety of their administration (9%).

[Comparison of data from registries of acute coronary syndromes RECORD and RECORD-2: management of patients and its results in noninvasive hospitals]

Positive changes are declared to occur during recent years in management of hospitalized patients with acute coronary syndromes (ACS) in Russia. Most of these changes are related to availability of invasive treatment. But considerable portion of patients (pts) are still treated in hospitals without facilities for invasive myocardial revascularization (noninvasive hospitals - NIHs). Aim of this study was to compare some characteristics of management of ACS in NIHs which participated in ACS registries RECORD (2007-2008, 8 NIHs from 6 cities; n=381) and RECORD-2 (2009-2011, 3 NIHs from 3 cities, n=680). Results. Groups of pts recruited in these NIHs had similar mean age and portion of women (67.6 and 66.5 years, 51.1 and 53.1 % in RECORD-2 and RECORD, respectively, p=0.64). Time from symptoms onset to hospitalization was shorter in RECORD-2 (3.2 vs 4.1 hours for ST-elevation [STE], =0.03; 4.0 vs 6.5 hours for non ST elevation [NSTE] ACS, <0.0001). Among RECORD-2 NSTEACS pts more had ST depressions (50.6 vs 28.7%, <0.0001), high risk of death according to GRACE score (39.1 vs 20.9 %, <0.0001), but less Killip class >II (15.0 vs 21.6%, p=0.025). No such differences existed among STEACS pts. Thrombolysis was more often used in RECORD-2 (62.6 vs 34.1%, <0.0001). Both STEACS and NSTEACS RECORD-2 pts more often received clopidogrel (63.5 vs 18.8%, p<0.0001, and 41.6 vs 11.1%, <0.0001, respectively). More NSTEACS RECORD-2 pts were given parenteral anticoagulants (93.4 vs 80.4%, <0.0001), low molecular weight heparins (23.4 vs. 3.4%, <0.0001) and fondaparinux (10.4 vs 0.7%, <0.0001), but still in 20% of NSTEACS RECORD-2 pts unfractionated heparin was given subcutaneously. Twenty RECORD-2 pts (2.9%) were transferred to invasive hospital but none during first 24 hours. There were no significant differences between registers in hospital mortality (20.0 vs 21.2%, =0.84; 4.2 vs 2.7%, =0.24 in STE and NSTE ACS pts of RECORD-2 and RECORD, respectively). Conclusions. Despite some improvement in management of pts occurring in 2-3 years NIHs mortality in STEACS remained very high. Numerically higher mortality in NSTEACS could be partially attributed to higher risk of RECORD-2 pts.

Snake venom metalloproteinases

Recent proteomic analyses of snake venoms show that metalloproteinases represent major components in most of the Crotalid and Viperid venoms. In this chapter we discuss the multiple activities of the SVMPs. In addition to hemorrhagic activity, members of the SVMP family also have fibrin(ogen)olytic activity, act as prothrombin activators, activate blood coagulation factor X, possess apoptotic activity, inhibit platelet aggregation, are pro-inflammatory and inactivate blood serine proteinase inhibitors. Clearly the SVMPs have multiple functions in addition to their well-known hemorrhagic activity. The realization that there are structural variations in the SVMPs and the early studies that led to their classification represents an important event in our understanding of the structural forms of the SVMPs. The SVMPs were subdivided into the P-I, P-II and P-III protein classes. The noticeable characteristic that distinguished the different classes was their size (molecular weight) differences and domain structure: Class I (P-I), the small SVMPs, have molecular masses of 20-30 kDa, contain only a pro domain and the proteinase domain; Class II (P-II), the medium size SVMPs, molecular masses of 30-60 kDa, contain the pro domain, proteinase domain and disintegrin domain; Class III (P-III), the large SVMPs, have molecular masses of 60-100 kDa, contain pro, proteinase, disintegrin-like and cysteine-rich domain structure. Another significant advance in the SVMP field was the characterization of the crystal structure of the first P-I class SVMP. The structures of other P-I SVMPs soon followed and the structures of P-III SVMPs have also been determined. The active site of the metalloproteinase domain has a consensus HEXXHXXGXXHD sequence and a Met-turn. The "Met-turn" structure contains a conserved Met residue that forms a hydrophobic basement for the three zinc-binding histidines in the consensus sequence.

Practice guidelines for the implementation of a quality program in thromboprophylaxis and treatment management in patients with venous thromboembolic disease

BACKGROUND

Venous thromboembolic disease is a major cause of morbidity and hospital mortality worldwide. Although exact figures are unknown in Mexico, achieving uniformity of criteria among the specialties involved in the prophylaxis and treatment will offer a clearer picture and contribute to a more rational and interdisciplinary approach in order to improve the quality of care for patients and increase the level of awareness of this entity.

DISCUSSION

For the preparation of this document, a total of 11 medical specialists from Mexico City and the interior of the country met along with a highly experienced professional from Chicago, IL, USA with wide experience in the field and knowledge of methodology for the development of a management algorithm for prophylaxis in at-risk patients of venous thromboembolic disease. The expert group met in plenary working sessions, managed uniform criteria and reached consensus agreement by issuing a series of useful recommendations for the care of patients with venous thromboembolism in Mexican hospitals.

CONCLUSIONS

In Mexico there is the need to develop and disseminate guidelines on thromboprophylaxis and treatment of venous thromboembolic disease because of the wide disparity of views or simple misinformation, leading to diagnostic and treatment behaviors unique to each institution.

A class of novel nitronyl nitroxide labeling basic and acidic amino acids: synthesis, application for preparing ESR optionally labeling peptides, and bioactivity investigations

Aimed at optional ESR label 2-(4'-hydroxyl)phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl was introduced into the guanido of L-Arg-OH, the omega-amino group of L-Lys-OH with methylcarboxyl as a linker, and into the beta-carboxyl of L-Asp-OH and the gamma-carboxyl of L-Glu-OH with ethylamino as a linker. It was explored that the synthetic 30 novel ESR labeling amino acid derivatives were stable enough to the reaction conditions of peptide synthesis. Their incorporation led to 12 novel ESR optionally labeling PAK, RGDS, RGDV, and ECG. A series of NO related chemical tests, the in vitro and in vivo assays of these peptides confirmed that this strategy was practical.

Clinical and biochemical predictors affect the choice and the short-term outcomes of different thrombolytic agents in acute myocardial infarction

BACKGROUND

The presence of plasminogen activator inhibitor-1, angiotensin-converting enzyme and others may play a role in unsuccessful recanalization after thrombolytic therapy.

OBJECTIVES

To find out the clinical and biochemical predictors that may affect the choice and short-term outcomes following different thrombolytic agents in acute myocardial infarction.

METHODOLOGY

Angiotensin-converting enzyme and plasminogen activator inhibitor-1 plasma levels of 184 patients with acute myocardial infarction, treated with streptokinase, metalyze or reteplase, were determined. Failure of thrombolysis was assessed by noninvasive reperfusion criteria. Prolonged hospitalization, impaired left ventricular ejection fraction and reinfarction were considered as short-term outcomes.

RESULTS

Patients who received streptokinase developed higher incidence of >50% resolution of ST-segment elevation (82.5 vs. 64.7%, P-value<0.05, in comparison with metalyze and 82.5 vs. 55.7%, P-value 0.001, in comparison with reteplase) than those who received other thrombolytic agents. High plasma angiotensin-converting enzyme was associated with prolonged hospitalization (55, 63 and 94%, P<0.02) following streptokinase, metalyze and reteplase, respectively. High plasma plasminogen activator inhibitor-1 is associated with impaired left ventricular ejection fraction (55.3, 76.7 and 68.5%, P<0.09), ST resolution<50% (13.2, 36.7 and 37.5%, P=0.03), ST resolution>50% (86.8, 63.3 and 62.5%, P=0.03) following streptokinase, metalyze and reteplase, respectively.

CONCLUSIONS

Rapid determination of pretreatment angiotensin-converting enzyme and plasminogen activator inhibitor-1 plasma levels in patients with acute myocardial infarction may influence the choice and outcomes of the thrombolytic agents. The presence of a high plasma level of either angiotensin-converting enzyme or plasminogen activator inhibitor-1 is significantly associated with adverse short-term outcomes after treatment with reteplase or metalyze.

Pharmacogenetics of Antithrombotic Drugs

Antithrombotic therapy has improved the prognosis of patients with venous or arterial thrombosis. However, there is substantial interindividual variability in the response to antithrombotic drugs. This variability is due, in part, to genetics, which may affect the efficacy and safety of drugs used in the treatment and prevention of thrombosis. Pharmacogenetics studies the genetic factors related to interindividual variability in the response to drugs. Various polymorphisms in genes of the hemostatic system that have been reported to be markers of susceptibility to thromboembolic disease also seem to be implicated in the response to antithrombotic therapy. These include polymorphisms in platelet receptors (platelet glycoproteins) and coagulation factors (factors II, V, XII, XIII). There is also growing evidence on genetic polymorphisms affecting the metabolism (cytochrome P450), disposition, transporter proteins or cellular receptors of antithrombotic drugs. This review summarizes current knowledge on the pharmacogenetics of antithrombotic therapy, paying special attention to four therapeutic groups: antiplatelet agents, anticoagulants (vitamin K antagonists and heparin), fibrinolytics and other drugs used for the prevention of cardiovascular risk, such as statins and hormone replacement therapy in the menopause. The potential relevance of pharmacogenetics in the future of antithrombotic therapy and the design of clinical trials is also explored.

Antithrombotic agents in cerebral ischaemia

The current evidence suggests that aspirin is treatment of choice when compared to anticoagulants for patients with non-cardioembolic stroke. The usefulness of combination therapy (aspirin vs. with or without warfarin) is still debated. Likewise the combination of Aspirin with clopidogrel has no added advantage (MATCH Trial). However anticoagulant therapy significantly benefits high-risk patients with atrial fibrillation in the elderly subjects whereas aspirin may still be the drug of choice in stroke prevention in low risk group in the younger age. There is dire need for well planned randomized double blind controlled studies to define the role of Antithrombotic agents in "cryptogenic stroke" (PFO/ASD related) antiphospholipid antibody syndrome, arterial dissections and intraluminal clot syndromes. Evaluation and treatment of associated risk factors in all categories needs greater emphasis.

Gender differences in the treatment and secondary prevention of CHD at population level

OBJECTIVES

Treatment and secondary prevention measures, received by persons with coronary heart disease (CHD), are insufficiently known at the moment. The aim of this study was to investigate the state of treatment and secondary prevention of CHD in a population-based sample and to analyze possible gender differences in different age groups.

DESIGN

300 men and 300 women with CHD were identified from a nationally representative health examination survey with 88% participation rate, carried out in Finland in 2000-2001.

RESULTS

Revascularization had been performed on 34% (95% confidence interval 29, 40%) of men and 13% (8, 18%) of women. Moreover, 76% (71, 81%) of the men and 63% (57, 69%) of the women used antithrombotic medications. Two thirds of both men and women used beta-blockers and one third lipid-lowering medication. Smoking was more common among men, whereas obesity and high total cholesterol concentration were more common among women.

CONCLUSIONS

Secondary prevention of CHD is far from optimal and there are gender differences in the care of CHD.

[Treatment of deep vein thrombosis. When to use which substance?]

Current antithrombotic therapy of deep vein thrombosis (DVT) consists of an initial course of heparin, followed by the secondary prevention with oral anticoagulation (OAC). Low molecular weight heparin has several advantages over unfractionated heparin, however, renal insufficiency has to be observed to avoid accumulation. The synthetic pentasaccharide Fondaparinux is a factor Xa inhibitor, that will shortly be available for the initial treatment of DVT. Oral anticoagulation with vitamin K antagonists (VKA) is highly effective, the standard target INR is 2.0-3.0. For a first episode of DVT the duration of OAC usually is six months, but has to be adjusted according to the estimated risk for recurrence. Because of the narrow therapeutic window of VKA, low molecular weight heparins are increasingly being used for secondary prevention in patients with an increased risk for bleeding, mostly in 1/2-therapeutic dose. At present, several new antithrombotic agents are being studied and may become available shortly for DVT treatment.

Inhibition of purified factor Xa amidolytic activity may not be predictive of inhibition of in vivo thrombosis: implications for identification of therapeutically active inhibitors

OBJECTIVE

In this study we test the hypothesis that blood/plasma-based prothrombinase assays, rather than inhibition of purified factor Xa (fXa), are predictive of in vivo antithrombotic activity.

METHODS AND RESULTS

Six fXa inhibitors with equivalent nanomolar Ki were studied in thrombin generation assays using human plasma/blood and endogenous macromolecular substrate. In all assays, benzamidine inhibitors were more potent (100 to 800 nmol/L) than the aminoisoquinolines (5 to 58 micromol/L) or neutral inhibitors (3 to 10 micromol/L). A similar rank order of compound inhibition was also seen in purified prothrombinase assays as well as in a rabbit model of deep vein thrombosis.

CONCLUSIONS

Assays using prothrombinase with protein substrates are better predictors of in vivo efficacy than fXa Ki using amidolytic substrates.

Clinical potential of intra-arterial thrombolytic therapy in patients with acute ischaemic stroke

Acute ischaemic stroke is a leading cause of mortality and morbidity around the world. An arterial occlusive lesion is found in the majority of patients with acute ischaemic stroke, and recanalisation has been shown to result in a better clinical outcome. The only widely approved recanalisation strategy is the use of intravenous alteplase (recombinant tissue-type plasminogen activator; tPA) within 3 hours of stroke onset. However, this therapy has limitations, and alternative or supplemental recanalisation strategies need to be considered in a large number of patients with acute ischaemic stroke. One such promising strategy is intra-arterial thrombolysis. This article reviews the pharmacology of the various drugs used for intra-arterial thrombolysis in the setting of acute ischaemic stroke and the results of the clinical trials that have studied their benefit. Three generations of thrombolytic agents have been available for clinical use so far. The first-generation agents such as streptokinase and urokinase were the first to be studied in acute stroke, and a number of positive case reports and series of their intra-arterial use have been reported from around the world. Second-generation products include alteplase and pro-urokinase. The clinical benefits of intra-arterial pro-urokinase were recently proven in a randomised, placebo-controlled study. Third-generation agents, such as reteplase, lanoteplase and tenecteplase, offer superior recanalisation rates with limited systemic adverse effects and might prove to be the agents of choice for intra-arterial acute stroke thrombolysis in the future. The exact administration regimens as well as the identification of patient sub-populations most likely to benefit from intra-arterial thrombolysis are subjects of current investigations, and hopefully firmer guidelines will be established in the next few years, once the results of the clinical trials are available.

Comparison of safety and efficacy of the various thrombolytic agents

Thrombolytic agents are in widespread use for the dissolution of arterial and venous pathologic thrombi. Clinical settings where thrombolysis has played an important role include the acute coronary syndromes, peripheral arterial occlusion, ischemic stroke, deep venous thrombosis, and pulmonary embolism. Thrombolytic agents have been successfully employed in each of these areas, achieving dissolution of the occluding thrombus, reconstitution of blood flow, and improvement in the status of the tissue bed supplied or drained by the involved vascular segment. All clinically available thrombolytic agents act through cleavage of the plasminogen molecule to its active form, plasmin. Despite this similar mechanism of action, the thrombolytic agents differ in several biochemical parameters, including fibrin specificity, fibrin affinity, and relative resistance to inactivating factors in the plasma. Whether these differences account for significant differences in clinical outcome is a matter of some dispute. It is quite possible that in vitro biochemical differences do not have meaningful clinical correlates. However, there exists some evidence to suggest that differences in the risk of distant hemorrhage, idiosyncratic reactions, and the rapidity of clot dissolution do exist. An ideal agent for peripheral vascular thrombolysis would be one that was specific in its actions at the site of pathologic thrombi yet left the important and desirable pathologic thrombi that seal vascular defects unscathed. Although such an agent has not yet been identified, an understanding of the mechanism of action and principles underlying pharmacologic thrombolysis provides the necessary foundation of knowledge to choose a particular thrombolytic agent for a given clinical scenario.

Current issues in the diagnosis and management of pediatric empyema

Empyema is a rare but recognized complication of bacterial pneumonia in children. The incidence of empyema may be rising as vaccination practices and antibiotic prescribing practices promote the emergence of more virulent and resistant organisms. Diagnostic methods vary widely, from thoracentesis to plain radiographs to detailed computed tomography scans. Treatment practices also vary, with some practitioners preferring medical treatment, others employing chest tube drainage or fibrinolytic therapy, and still others aggressively pursuing surgical options. Further study is needed to define the ideal management of empyema. The authors review the current literature and propose an updated management algorithm that incorporates accepted practices as well as emerging trends in diagnosis and management of empyema.

Acute coronary syndromes: 2. Antiplatelet agents

Therapies with novel antiplatelet agents and anticoagulants are the focus of current research. When used separately or in combination, these agents prevent generation of thrombin by activated platelets. The new therapies, in conjunction with judicious use of fibrinolytic drugs and mechanical interventions, are revolutionizing the management of patients with acute coronary syndromes.

[Main antithrombotic drugs in the therapy and prevention of arterial and venous thrombosis]

The author reviews the use of the main antithrombotic drugs (thrombolytics, dicumarol compounds, heparins and anti-platelet drugs) in the treatment and prophylaxis of the main nosographic syndromes of arterial and venous thrombosis. In the context of arterial thrombosis the paper initially reports the results of the main controlled trials on ischemic cardiopathy (treatment of acute infarction, primary and secondary prophylaxis for re-infarction, post-infarction ventricular thrombosis, stable and instable coronary angor, percutaneous angioplasty, aortocoronary by-pass, stent, valve prosthesis, atrial fibrillation). Turning to peripheral arteriopathies the treatment of acute attacks is death with separately from prophylactic treatment (reduction of atheromatous progression, improved vascular perfusion, reduction of concomitant cardiac and cerebral events, behaviour of carotid stenoses). Vascular cerebropathy is examined during the acute (treatment of ictus in early days) and later phases (prophylaxis of recidivation of ictus). With regard to venous thrombosis, the paper separates the treatment of profound thrombosis and pulmonary embolism (often secondary to the former) from prophylaxis of profound thrombosis; the latter is classified into forms occurring during general surgery (abdominal, pelvic, urologic), orthopedic surgery (hip prosthesis, gonopathies) and general medicine. The author ends the review by making a schematic analysis of the areas of elective use of the above antithrombotic drugs with reference to the nosographical forms examined in the paper.

[New antithrombotic agents]

The wide range of compounds currently being developed is the result of the continuing need for validated new antithrombotic agents. The prevention and treatment of venous thrombosis is predominated by anticoagulants: low molecular weight heparins, and potentially new antithrombin agents including hirudin. The effectiveness of new antiplatelet agents, and particularly c7E3 and integrelin, confirms the hypothesis concerning the role played by platelets in thrombogenesis in coronary arteries. But, due to the proaggregating effect of thrombin, anticoagulants could also have an important role in preventing arterial clots, either when given alone or in combination. Finally, the development of antithrombin and anti-platelet-glycoprotein IIb IIIa given orally is one of the major objectives of current research. Until the ideal antithrombotic agent is discovered, multiple-drug regimens combining anticoagulants and/or antiplatelet agents could be proposed in patients with a very high risk of thrombosis. Such regimens must taken into account the increased risk of bleeding and be adapted on the basis of careful laboratory surveillance.

Advances in antithrombotic therapy: novel agents

Most of the clinical evaluation of the direct thrombin inhibitors has been in coronary artery disease. The recent clinical reports suggest that there is a narrower window of safety with recombinant hirudin than initially thought particularly when it is used in conjunction with thrombolytic agents and aspirin in acute myocardial infarction. The efficacy data, however, indicate that the direct thrombin inhibitors have great potential particularly in the initial management of patients with acute unstable angina and non-Q-wave infarction. There is much to learn regarding the mechanism of action, optimal dose, and optimal concomitant therapy in the use of direct thrombin inhibitors in the management of acute coronary ischaemia; and since hirudin and other direct thrombin inhibitors have so much potential in the management of acute coronary ischaemia, it is critical that dose-finding studies be performed to determine safe regimens of these agents to allow their evaluation in large-scale trials with important clinical outcomes. The direct thrombin inhibitors have also shown to have promise in the prevention of deep vein thrombosis in high-risk surgical patients. There is limited clinical data on the other novel anticoagulants which are currently being developed.

[The promises of new antithrombotic agents]

Most new antithrombotic drug development projects are focused on the improvement of myocardial infarction treatment at the acute phase. New thrombolytic drugs do not seem to be as attractive as adjunctive therapy, such as antiplatelet and antithrombotic agents, as well as inhibitors of thrombin generation. The current tendency is to select very specific molecules. The difficulty in developing these drugs must not be underestimated: they will be compared to very active drugs, such as aspirin, heparin or streptokinase; the therapeutic margin of antithrombotic therapy is very narrow; a clinical benefit will have to be shown.

Antithrombotic treatment of cerebrovascular disease

The most common type of cerebrovascular disease is ischaemia or infarction from atherothrombosis or cardiac embolism. Antithrombotic treatment with an antiplatelet agent or anticoagulant assumes a prior clinical classification into categories of transient ischaemic attack (TIA) or minor stroke, acute partial stable stroke, stroke-in-progression, and completed stroke. Aspirin reduces the risk of stroke, myocardial infarction, and death after TIA or minor stroke secondary to atherothrombosis. Aspirin is effective in both sexes at a dose of 300 or 1200 mg/day. Ticlopidine (500 mg/day), a new antiplatelet agent, is more effective than aspirin in preventing stroke and death in patients with TIA or minor stroke. Ticlopidine (500 mg/day) is effective in preventing recurrent stroke, myocardial infarction, or vascular death in patients with completed stroke. Aspirin has not been directly shown to be effective after completed stroke. No clear evidence exists for the use of anticoagulants in atherothrombotic cerebral vascular disease in patients presenting with TIA or minor stroke, acute partial stable stroke, stroke-in-progression, or completed stroke. Anticoagulation for rheumatic valvular heart disease is effective in preventing recurrent embolism. Long-term anticoagulation of patients with mechanical prosthetic valves protects against initial embolism and prevents recurrent embolism. The addition of aspirin (500-1000 mg/day) to warfarin reduces the rate of cerebral embolism from mechanical prosthetic heart valves but is associated with increased bleeding. The addition of dipyridamole (400 mg/day) to warfarin may be more effective than aspirin in reducing the rate of cerebral embolism from mechanical prosthetic heart valves and has fewer bleeding side-effects. Anticoagulation during the hospital phase of myocardial infarction reduces the incidence of systemic embolism/stroke. Long-term anticoagulation of patients after the hospital phase of myocardial infarction reduces the incidence of systemic embolism/stroke, recurrent myocardial infarction and death. Prophylactic anticoagulant treatment of patients with non-valvular atrial fibrillation reduces the incidence of embolism, but the optimal duration of treatment is not known. Immediate anticoagulation of patients with completed cardioembolic stroke is safe and effective in preventing recurrent embolism.

The antithrombic drugs in clinical practice

The rational use of antithrombic drugs centres on the fundamental differences in the pathogenesis of arterial or venous thrombosis. The major role of platelets in the development of occlusion in arteries contrasts with prominent fibrin deposition in the slower moving venous blood. Logically, antiplatelet agents are used to treat patients at high risk from arterial disease and anticoagulants for those with venous thrombo-embolism. These sound theoretical principles have been linked to steady improvement in diagnostic techniques, and there now exists an extensive literature on available drugs and their clinical evaluation. It is therefore surprising how little agreement exists on the practical use of the antithrombic drugs. In patients with coronary artery disease, secondary prevention of myocardial infarction is favourably influenced by administration of aspirin, dipyridamole or sulphinpyrazone. However, differences are not statistically significant so that confident recommendations for their use cannot yet be made. In mitral valve disease, anticoagulants are effective in reducing systemic thrombo-embolism; in patients with cardiac prostheses, dipyridamole should be added. In the cerebral circulation, vertebrobasilar and carotid ischaemia need to be distinguished and suitable lesions surgically corrected. Patients not undergoing endarterectomy are divided into two groups. In those with symptoms stable for more than 3 months, aspirin alone is sufficient; patients with recent deterioration or a shorter history are best treated with conventional anticoagulants followed by the addition of aspirin. In venous thrombo-embolic disease, heparin prophylaxis should be combined with reversal of identifiable risk factors. In treating the acute event, anticoagulation, with or without preceding thrombolytic therapy, is preferred. In addition, the clinician must select an antithrombic regimen o take into account the possibility of drug interaction, the need for and feasibility of laboratory monitoring, and the total number of medicines prescribed for the patient. Failure to restrict tablets to manageable numbers will lead to poor compliance and unpredictable therapeutic response.