Platelet function during and after thrombolytic therapy for acute myocardial infarction with reteplase, alteplase, or streptokinase

Acute myocardial infarction and ischaemic stroke: differences and similarities in reperfusion therapies-a review

Acute ST-elevation myocardial infarction (STEMI) and acute ischaemic stroke (AIS) share a number of similarities. However, important differences in pathophysiology demand a disease-tailored approach. In both conditions, fast treatment plays a crucial role as ischaemia and eventually infarction develop rapidly. Furthermore, in both fields, the introduction of fibrinolytic treatments historically preceded the implementation of endovascular techniques. However, in contrast to STEMI, only a minority of AIS patients will eventually be considered eligible for reperfusion treatment. Non-invasive cerebral imaging always precedes cerebral angiography and thrombectomy, whereas coronary angiography is not routinely preceded by non-invasive cardiac imaging in patients with STEMI. In the late or unknown time window, the presence of specific patterns on brain imaging may help identify AIS patients who benefit most from reperfusion treatment. For STEMI, a uniform time window for reperfusion up to 12 h after symptom onset, based on old placebo-controlled trials, is still recommended in guidelines and generally applied. Bridging fibrinolysis preceding endovascular treatment still remains the mainstay of reperfusion treatment in AIS, while primary percutaneous coronary intervention is the strategy of choice in STEMI. Shortening ischaemic times by fine-tuning collaboration networks between ambulances, community hospitals, and tertiary care hospitals, optimizing bridging fibrinolysis, and reducing ischaemia-reperfusion injury are important topics for further research. The aim of this review is to provide insights into the common as well as diverging pathophysiology behind current reperfusion strategies and to explore new ways to enhance their clinical benefit.

Efficacy and Safety of Alteplase on Treatment of Acute Single Small Subcortical Infarction

BACKGROUND

Single Small Subcortical Infarction (SSSI) is an isolated small infarction in the territory of perforating artery with a maximum diameter of 20 mm in axial Diffusion-Weighted Imaging (DWI). About 20 to 30% of SSSI patients were reported to have Early Neurological Deterioration (END) in the acute phase, which brought adverse effects on long-term outcomes. The effect of the alteplase on the outcome of SSSI, especially END and long-term outcomes, was ambiguous.

OBJECTIVE

The study aims to find out the efficacy and safety of intravenous recombinant tissue Plasminogen Activator (rt-PA) on long-term and short- outcomes of patients with SSSI as compared to patients who received standard medical care.

METHODS

The patients were retrospectively screened from a stroke registry of the neurology department of 1st Affiliated Hospital of Zhengzhou University from January 2013 to December 2020. Based on treatment modality, patients were dichotomized into alteplase and standard medical care groups. To minimize confounding factors in subgroups, a propensity score matching analysis was done. The primary outcome was the favorable functional outcome 3 months after stroke onset, defined by attaining a score of ≤2 points on the modified Rankin scale (mRS), secondary outcome was the prevention of occurrence of END, defined as an increase of ≥2 points in the total score or ≥1point on motor subunit in the National Institutes of Health Stroke Scale (NIHSS) score within 72 hours after admission, safety features were symptomatic intracranial hemorrhage (sICH) or death. Multivariate analysis was employed to find the efficacy and safety of alteplase in the treatment of SSSI.

RESULTS

A total of 717 patients with anterior circulation SSSI were selected, and 132 were included in the final analysis. Forty-five patients were treated with alteplase within 4.5 hours and 87 with standard medical care, and 44 pairs were successfully matched by propensity score. Pre-match data showed that the alteplase thrombolysis group showed a higher proportion of favorable outcomes at 3-month follow-up [OR=0.315, 95%CI:0.106, 0.931, P = 0.037] but did not reduce the incidence of END compared with the non-thrombolytic group [OR = 1.033, 95%CI:0.417,2.554, P = 0.943]. Post-match data showed that the alteplase group also showed a higher proportion of favorable outcomes at 3-month follow-up [OR = 0.247, 95%CI: 0.074, 0.830, P = 0.024]; however, it did not reduce the incidence of END compared with the non-thrombolytic group [OR = 1.241, 95%CI: 0.433,3.554, P = 0.688]. There was one case of asymptomatic ICH in alteplase treated patients.

CONCLUSION

Patients with SSSI in the anterior circulation are more likely to achieve 3 months favorable outcomes than those who were treated with standard medical care; however, treatment with alteplase may not prevent the occurrence of END.

Mean Platelet Volume is a Prognostic Marker in Acute Ischemic Stroke Patients Treated with Intravenous Thrombolysis

BACKGROUND AND OBJECTIVES

There is conflicting data regarding the association between platelet parameters and prognosis of stroke patients treated with intravenous thrombolysis. We aimed to analyze this association in a cohort of patients treated with rtPA.

MATERIAL AND METHODS

Retrospective, observational study in adult ischemic stroke patients treated with rtPA between January 2015 and February 2017. Demographic and clinical characteristics, stroke severity (NIHSS), etiology (TOAST), mean platelet volume (MPV), platelet count (PC), platelet distribution width (PDW) and functional outcome (mRS) at discharge and 90 days were recorded. The association between platelet parameters and unfavorable prognosis (mRS 3-6) was tested using non-parametric tests and logistic regression analysis.

RESULTS

267 patients were included, 134 (50.2%) females, with a median (IQR) age of 74 years (64-82). The median admission NIHSS was 14 (8-19) and the most frequent etiology was cardioembolism (n = 115, 43.1%). At discharge, 170 (63.7%) patients had mRS 3-6. MPV values were higher in patients with mRS 3-6 (median 8.2fL versus 7.8fL, p = 0.013). This association remained significant (OR = 1.36, 95% CI 1.003-1.832, p = 0.048) after adjustment for variables associated with prognosis. There were no significant associations between other platelet parameters and prognosis. There was a trend to unfavorable prognosis at 90 days in patients with higher MPV. Regarding the association between platelet parameters and hemorrhagic transformation, higher PDW was associated with more severe hemorrhagic transformation (PH1/PH2).

CONCLUSIONS

Higher MPV values were associated with unfavorable prognosis at discharge in patients treated with intravenous thrombolysis. Future studies should address its added value in stroke prediction models.

Ticagrelor versus clopidogrel in patients with STEMI treated with thrombolysis: the MIRTOS trial

AIMS

We aimed to demonstrate whether coronary microvascular function is improved after ticagrelor administration compared to clopidogrel administration in STEMI subjects undergoing thrombolysis.

METHODS AND RESULTS

MIRTOS is a multicentre study of ticagrelor versus clopidogrel in STEMI subjects treated with fibrinolysis. We enrolled 335 patients <75 years old with STEMI eligible for thrombolysis, of whom 167 were randomised to receive clopidogrel and 168 to receive ticagrelor together with thrombolysis. Primary outcome was the difference in post-PCI corrected TIMI frame count (CTFC). All clinical events were recorded in a three-month follow-up period. From the 335 patients who were randomised, 259 underwent PCI (129 clopidogrel and 130 ticagrelor) and 154 angiographies were analysable for the study primary endpoint. No significant difference was found between the clopidogrel (n=85) and ticagrelor (n=69) groups for CTFC (24.33±17.35 vs 28.33±17.59, p=0.10). No significant differences were observed in MACE and major bleeding events between randomisation groups (OR 2.0, 95% CI: 0.18-22.2, p=0.99).

CONCLUSIONS

Thrombolysis with ticagrelor in patients <75 years old was not able to demonstrate superiority compared to clopidogrel in terms of microvascular injury, while there was no difference between the two groups in MACE and major bleeding events.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02429271. EudraCT Number 2014-004082-25.

Insights for increased risk of failed fibrinolytic therapy and stent thrombosis associated with COVID-19 in ST-segment elevation myocardial infarction patients

Important health resources are dedicated worldwide to the management of COVID‐19. This new disease, due to its large diffusion, may significantly hamper the prognosis of other pathologies, such as ST‐segment elevation myocardial infarction (STEMI) because of (a) a possible direct negative impact and (b) shortage of first response medical resources and increased delays to reperfusion. We report the case of a 68‐year‐old man admitted for anterior STEMI and asymptomatic COVID‐19. Due to extended transportation delays to a cathlab, he received intravenous fibrinolytic therapy, which failed. Reperfusion was achieved with rescue coronary angioplasty, but the patient experienced two episodes of acute stent thrombosis at 2‐ and 36‐hr following admission and despite optimal medical therapy. He finally died because of cardiogenic shock. This raises concerns about a possible increase in platelet aggregability associated with COVID‐19 leading to an increased risk of stent thrombosis, particularly in the context of STEMI. This pleads for the promotion of primary coronary angioplasty as the first‐choice revascularization technique in this population and the use of new generation P2Y12 inhibitors. In addition, the use of GPIIb/IIIa inhibitors may be considered in every STEMI patient with COVID‐19 to prevent the risk of acute stent thrombosis.

Effect of alteplase on platelet function and receptor expression

Objective

To investigate the role of alteplase, a widely-used thrombolytic drug, in platelet function.

Methods

Human platelets were incubated with different concentrations of alteplase followed by analysis of platelet aggregation in response to adenosine diphosphate (ADP), collagen, ristocetin, arachidonic acid or epinephrine using light transmittance aggregometry. Platelet activation and surface levels of platelet receptors GPIbα, GPVI and αIIbβ3 were analysed using flow cytometry. The effect of alteplase on clot retraction was also examined.

Results

This study demonstrated that alteplase significantly inhibited platelet aggregation in response to ADP, collagen and epinephrine in a dose-dependent manner, but it did not affect ristocetin- or arachidonic acid-induced platelet aggregation. Alteplase did not affect platelet activation as demonstrated by no differences in P-selectin levels and PAC-1 binding being observed in collagen-stimulated platelets after alteplase treatment compared with vehicle. There were no changes in the surface levels of the platelet receptors GPIbα, GPVI and αIIbβ3 in alteplase-treated platelets. Alteplase treatment reduced thrombin-mediated clot retraction.

Conclusions

Alteplase inhibits platelet aggregation and clot retraction without affecting platelet activation and surface receptor levels.

Efficacy evaluation of reteplase in a novel canine acute pulmonary thromboembolism model developed by minimally invasive surgery and digital subtraction angiography

Purpose

In order to evaluate the thrombolytic effects of reteplase in pulmonary thromboembolism (PTE), we developed a novel canine PTE model. The efficacy of reteplase against PTE in comparison to alteplase was clarified for the first time, and this PTE model could be further applied to studies of novel thrombolytic therapies.

Patients and methods

Twenty-four dogs were divided into four groups: sham operation, vehicle, alteplase, and reteplase. Autologous thrombi/saline were injected into the pulmonary artery, and thrombolytic agents were administrated. Thrombus formation and dissolution were monitored by real-time digital subtraction angiography (DSA), and pulmonary pressures were measured simultaneously. Blood coagulation, blood gas, hematology, and histopathologic examinations were used as subsidiary methods.

Results

The canine PTE model was established with a significant decrease of blood flow and ~75% blocking area. Administration of reteplase (0.6 mg/kg) resulted in effective thrombus dissolution with a recovery of over 80% blood flow, as effective as alteplase (1.6 mg/kg). Correspondingly, the elevated pulmonary systolic, diastolic, and mean arterial pressures declined to the normal level. Blood coagulation was changed by reteplase, with a dramatic elongation of prothrombin time, activated partial thromboplastin time, and thrombin time, even longer than alteplase. In contrast to the vehicle group, no obvious pathological changes were found in the two thrombolytic groups. Hematological, blood biochemical, and blood gas results also indicated that reteplase had no adverse reactions in this PTE model.

Conclusion

Reteplase proved to be an effective and safe therapy for PTE for the first time, and a small dosage of reteplase exerted an efficacy comparable to the routine dosage of alteplase. Our findings indicated the potential of reteplase as clinical treatment against PTE. This technically innovative, stability- and validity-proved canine PTE model developed by minimally invasive surgery and DSA resembled major clinical features. This may further facilitate our understanding of thrombotic disorders and development of prophylactic and therapeutic approaches.

Providing full recovery with single-dose intravenous reteplase in a patient presented to emergency department with acute ischemic stroke

Administration of intravenous reteplase might be a choice of treatment of acute ischemic stroke.

Anxiety is Not Manifested by Elevated Heart Rate and Blood Pressure in Acutely Ill Cardiac Patients

BACKGROUND

Accurate assessment of anxiety in cardiac patients is important because anxiety is associated with adverse outcomes. Clinicians often use heart rate and blood pressure as indicators of anxiety; however, little is known about whether these measures accurately reflect anxiety in acutely ill patients.

AIMS

The purpose of this study was to determine whether heart rate and blood pressure were related to level of anxiety in patients with chronic advanced heart failure (HF), patients with acute myocardial infarction (AMI), and healthy individuals.

METHODS AND RESULTS

In this descriptive, correlational study, anxiety, heart rate, and blood pressure were measured at the same time in three groups of individuals: (1) 54 patients hospitalized for AMI; (2) 32 patients with chronic advanced HF; and (3) 31 healthy individuals. State anxiety was measured using the anxiety subscale of the Brief Symptom Inventory. Heart rate and blood pressure data were collected immediately prior to the anxiety assessment. Data were collected in the outpatient setting for patients with HF and healthy individuals. For patients with AMI, data were collected a mean of 48+/-33 h after admission. There were no correlations between anxiety and heart rate or diastolic blood pressure. Higher anxiety was associated with lower systolic blood pressure in patients with AMI (r=-0.23, P<0.05) and in healthy individuals (r=-0.27, P<0.05).

CONCLUSION

Elevated heart rate and blood pressure do not accurately reflect level of anxiety as reported by patients with HF or AMI and healthy individuals, and thus cannot be used to assess anxiety in acutely ill patients. Clinicians who use changes in heart rate or blood pressure as indicators of anxiety may fail to recognize and treat anxiety, placing their patients at high risk for both immediate and long-term complications.

Platelet activation in myocardial ischemic syndromes

Platelets play a central role in the pathogenesis of atherosclerosis and thrombosis. Platelet adhesion and aggregate formation are critical events that occur in unstable coronary syndromes. Platelet activation precedes the formation of homotypic and heterotypic aggregates. In the last 10 years, researchers have described the presence of activated platelets in the systemic circulation in various cardiovascular disease states, particularly acute coronary syndromes. This review describes the evidence for platelet activation in acute myocardial ischemic syndromes, describes the pathophysiology responsible for its occurrence, and discusses how platelet activation and reactivity may affect the use of concomitant drug therapies and patient prognosis.

Acute vertebrobasilar occlusion: current treatment strategies

Acute vertebrobasilar occlusion (VBO) remains a disease with a high mortality. Local intraarterial fibrinolysis (LIF) can reduce the mortality rate from about 90 to 60%. The combined therapy of i.v. Abciximab and i.a. rt-PA with additional PTA/stenting may improve neurological outcome and significantly reduce mortality, despite an increase of overall bleeding complications. Additional PTA/stenting is an important treatment factor in cases of atherothrombotic occlusion. In embolic occlusions, mechanical catheter devices, such as basket or snare devices or rheolytic systems, are promising therapies for the near future. This article describes diagnostic criteria and treatment factors in acute VBO. Different treatment strategies, such as i.v. and i.a. fibrinolysis, adjunctive application of GP IIb/IIIa inhibitors, PTA/stenting and mechanical embolectomy are addressed in detail.

Changes in oxidative stress haemostatic parameters during the thrombolytic treatment of pulmonary embolism

A pulmonalis embolia a harmadik leggyakoribb cardiovascularis halálok. A masszív tüdőembólia thrombolysiskezelése kapcsán vérzéses szövődmény, reembólia léphet fel, a kórállapotot oxidatív stressz kíséri. Célok: Vizsgálatunkban az akut tüdőembólia rögoldó kezelése során elemeztük a thrombocytaaggregáció, a haemostaseologiai paraméterek, a leukocytaaktiváció és az oxidatív stressz markereinek változásait. Módszer: 15 beteget választottunk be, akik ultranagy dózisú sztreptokináz- ( n = 8) vagy altepláz- ( n = 7) kezelésben részesültek. Artériás vérmintát vettünk a thrombolysis előtt, azt követően pedig az első 24 órában 4 óránként, majd a 36. órában, és a 2., 3., 4., 5. és 30. napon. Mértük a spontán és az adrenalin, a kollagén és az adenozin-difoszfát indukálta thrombocytaaggregációt. A D-dimer- és fibrinogénszinteket az első napon 8 óránként, majd a fenti időpontokban egy alkalommal vizsgáltuk. Az oxidatív stressz és a leukocytaaktiváció elemzésére a thrombolysis előtt, a kezelést követően a 8. órában, majd az 1., 3., 5. és 30. napon vettünk vérmintákat. Az oxidatív stressz változásának nyomon követésére plazmából és teljes vérből malondialdehid, redukált glutation-, plazmaszulfhidrilcsoport-szinteket, szuperoxid-dizmutáz- és mieloperoxidázenzim-aktivitást mértünk. A teljes vér gyöktermelő kapacitását, vizsgálatát kemilumineszcenciával végeztük. Áramláscitometriával mértük a leukocyták által expresszált CD11a, CD18 és CD97 felszíni antigéneket. Eredmények: Az adrenalin indukálta thrombocytaaggregáció a 4. és a 8. órában csökkent ( p < 0,03), és szignifikánsan alacsony tartományban maradt a 36. órától a 3. napig az alteplázcsoporthoz képest. A sztreptokinázzal kezelteknél az adenozin-difoszfát indukálta aggregáció a 4. órában csökkent a kiindulási értékhez képest ( p < 0,05), kollagén esetében ugyanez a csökkenés a 4. és a 8. órában szignifikáns. A fibrinogénszintek a thrombolysist követően mindkét kezelési csoportban szignifikánsan csökkentek, míg a D-dimer a 8. órában szignifikánsan megemelkedett. Spontán thrombocytaaggregációt egyetlen mérési időpontban sem találtunk, jelentős vérzés, reembólia nem lépett fel. Az emelkedett malondialdehid-, reaktívoxigéngyök- és mieloperoxidáz-szintek, a csökkent redukált glutation- és plazmaszulfhidril-szintek a tüdőembóliás betegekben jelen lévő fokozott oxidatív stresszre utalnak. A thrombolysist követően a malondialdehid szignifikánsan emelkedik, a redukált glutation pedig csökken. A reaktív oxigéngyökök termelése a 3. és 5. nap között a legmagasabb. A thrombolysist kifejezett granulocyta és monocyta CD11a- és CD18-, valamint granulocyta CD97-expresszió-csökkenés kíséri ( p < 0,05). Következtetések: A masszív/szubmasszív pulmonalis embolia és az alkalmazott thrombolysis károsítja a thrombocytafunkciókat. A tüdőembólia reperfúziója során a fibrinogénszint csökkenése szignifikáns korrelációt mutat a tüdőperfúzió javulásával, ezek alapján a fibrinogénszint változása jól alkalmazható marker lehet a thrombolysis eredményességének akut felmérésére. Masszív/szubmasszív pulmonalis emboliás betegeknél a thrombolysis előtt fokozott oxidatív stressz állt fenn. Igazoltuk, hogy TL-t követően az oxidatív stressz és a leukocytaaktiváció még kifejezettebb, és e paraméterek csak a 30. napra normalizálódnak.

Time course of platelet aggregation during thrombolytic treatment of massive pulmonary embolism

We studied changes in platelet aggregation and fibrinogen levels during thrombolysis with massive or submassive pulmonary embolism. Fifteen patients were randomized into ultrahigh-dose streptokinase (UH-SK n = 8) or alteplase (tPA n = 7) groups. Arterial blood samples were taken before and after thrombolysis every 4 h between 4 and 36 h, and once daily between 2 and 30 days. In-vitro platelet aggregation was examined as spontaneous (0.9% NaCl) and induced aggregation with adrenaline 10 micromol/l, collagen 2 microg/ml and ADP 10 micromol/l. D-dimer and fibrinogen were measured every 8 h on first day, and later as above. In the UH-SK group, adrenaline-induced platelet aggregation decreased at 4 and 8 h compared with baseline (P < 0.03). Adrenaline-induced platelet aggregation was significantly lower in the UH-SK group than in the tPA group at 36 h and on day 3 (P < 0.03). Platelet aggregation induced by ADP was lower at 4 h than at baseline in the UH-SK group (P < 0.05). Collagen-induced platelet aggregation was lower at 4 and 8 h than at baseline (P < 0.05) in the UH-SK group. Compared with baseline, fibrinogen levels decreased in both groups after thrombolysis. D-dimer levels were elevated in both groups at 8 h (tPA group, P < 0.0004; UH-SK group, P < 0.05). Spontaneous platelet aggregation, major bleeding or re-embolism was not documented. Platelet aggregation decreased after thrombolysis with UH-SK for 12 h, in comparison tPA caused an insignificant decrease. Fibrinogen level decreased with UH-SK treatment for 5 days but in case of tPA we could not measure significant changes. According to our findings, tPA is a more suitable drug but streptokinase is also effective because of its cost-benefit ratio.

Combined intravenous and intra-arterial approach in acute stroke treatment

Despite the significant improvement in the outcome of ischaemic stroke with the use of intravenous recombinant tissue plasminogen activator, experience has shown limitations of the sole use of this approach in acute stroke treatment. This has encouraged the search for alternative managements for acute stroke. The combined use of intravenous/intra-arterial therapy is one such alternate treatment, if used in the right setting. In this review, the authors discuss the advantages and limitations of using this approach, together with an overview of the available therapies used through each route. The authors discuss the process of patient selection using clinical, as well as state of the art imaging modalities.

Reteplase: a review of its use in the management of thrombotic occlusive disorders

Reteplase (Retavase) is a plasminogen activator, mimicking endogenous tissue plasminogen activator (t-PA), a serine protease, converting plasminogen to plasmin and thereby precipitating thrombolysis. It is a third-generation recombinant form of t-PA that operates in the presence of fibrin (i.e. it is fibrin specific). Reteplase can be administered as a bolus dose (nonweight-based) rather than an infusion, which promotes rapid and safe administration. The ease of administration of this reteplase dosage regimen (two 10U bolus doses, each over 2 minutes, 30 minutes apart) is conducive to prehospital initiation of thrombolytic treatment in patients with ST-segment elevation myocardial infarction (STEMI), which reduces the time to treatment, a critical factor in improving long-term survival. In large randomized clinical trials of patients with STEMI, reteplase was superior to alteplase for coronary artery patency (according to TIMI [thrombolysis in myocardial infarction] flow) at 60 and 90 minutes, but there was no significant difference between agents for mortality rate and incidence of intracranial bleeding. The 35-day mortality rates were equivalent for reteplase and streptokinase recipients; there was reduced incidence of some cardiac events with reteplase versus streptokinase, but a greater incidence of hemorrhagic stroke. Reteplase has also shown thrombolytic efficacy (in nonapproved indications) as a catheter-directed intra-arterial or intravenous infusion for peripheral vessel occlusions, as 5-minute bolus doses (in 1U increments) for acute ischemic stroke, as a low-dose solution for occluded catheters or grafts, and as an intravenous double bolus for massive pulmonary embolism. Across studies in these indications, the incidence of bleeding complications associated with reteplase treatment appeared to be similar to that associated with other thrombolytic agents. With its efficacy, and the ease of administration of the bolus doses potentially minimizing dosage errors when treatment is administered under time pressure, reteplase is a valuable option for pre- or in-hospital thrombolytic treatment in patients with STEMI, and is a useful thrombolytic for the treatment of the other thrombotic occlusive disorders described.

Psychosocial factors and their association with clinical outcomes in patients with heart failure: why clinicians do not seem to care

Poor quality of life, social isolation, depression and anxiety all have been linked to increased risk of rehospitalization and mortality in patients with heart failure. Yet, despite evidence of their importance to outcomes in heart failure patients, psychosocial factors are assessed and treated infrequently in clinical practice. Potential reasons for this include: (1) inadequate dissemination of research about the link between psychosocial factors and outcomes; (2) insufficient training in heart-mind interactions that precludes clinicians from taking advantage of what is known; (3) perceived problems with interventions or with the science of heart-mind interactions that interfere with acceptance of what is known; (4) concerns about how to measure psychosocial factors in clinical practice; and (5) lack of curiosity from clinicians about the role of psychosocial factors in their patients. In this article, each of these possible explanations is explored and recommendations suggested.

Psychosocial issues in patients with congestive heart failure

Psychosocial issues are important variables that need to be addressed in patients with congestive heart failure (CHF). Unfortunately, these issues are often overlooked. Depression and lack of social support have been shown to have a negative impact on patients with CHF. Patients with CHF who are depressed or who lack social support have been shown to have increased morbidity and hospital readmission rates, to be less adherent to their medical regimen, and to have an overall increase in cost of care. The variables are often interrelated, as high levels of social support may lessen the impact of depression on mortality. In addition, certain biologic factors may influence the impact of psychosocial factors in patients with CHF. This review addresses the effects of depression, treatment adherence, and social support in patients with CHF and suggests interventions targeted to these problems. Health care professionals must assess these issues in all patients with CHF, address their specific needs, and intervene appropriately when warranted.

Abciximab, eptifibatide, and tirofiban exhibit dose-dependent potencies to dissolve platelet aggregates

Platelet GPIIb/IIIa antagonists are not only used to prevent platelet aggregation, but also in combination with thrombolytic agents for the treatment of coronary thrombi. Recent data indicate a potential of abciximab alone to dissolve thrombi in vivo. We investigated the potential of abciximab, eptifibatide, and tirofiban to dissolve platelet aggregates in vitro. Adenosine diphosphate (ADP)-induced platelet aggregation could be reversed in a concentration-dependent manner by all three GPIIb/IIIa antagonists when added after the aggregation curve reached half-maximal aggregation. The concentrations chosen are comparable with in vivo plasma concentrations in clinical applications. Disaggregation reached a maximum degree of 72.4% using 0.5 microg/ml tirofiban, 91.5% using 3.75 microg/ml eptifibatide, and 48.4% using 50 microg/ml abciximab (P < 0.05, respectively). A potential fibrinolytic activity of the GPIIb/IIIa antagonists was ruled out by preincubation with aprotinin or by a plasma clot assay. A stable model Chinese hamster ovary (CHO) cell line expressing the activated form of GPIIb/IIIa was used to confirm the disaggregation capacity of GPIIb/IIIa antagonists found in platelets. Not only abciximab, but also eptifibatide and tirofiban have the potential to disaggregate newly formed platelet clusters in vitro. Because enzyme-dependent fibrinolysis does not appear to be involved, competitive removal of fibrinogen by the receptor antagonists is the most likely mechanism.

Effects of different thrombolytic treatment regimen with abciximab and tirofiban on platelet aggregation and platelet-leukocyte interactions: a subgroup analysis from the GUSTO V and FASTER trials

BACKGROUND

Due to considerably high rates of reocclusion under standard thrombolytic therapy GP IIb/IIIa inhibitors have been combined with thrombolytics to improve therapeutic outcomes. Potential reasons for arterial reocclusion may be increased platelet activation, interaction of platelets with other cell types such as leukocytes and inadequate drug dosing due to lack of ideal platelet monitoring. We compared combination therapy regimens consisting of GP IIb/IIIa inhibitors and thrombolytics with respect to platelet inhibition and platelet-leukocyte interactions.

METHODS AND RESULTS

From the GUSTO V trial (standard rPA vs. reduced dose rPA and abciximab) and the FASTER trial (standard TNK-tPA vs. reduced dose TNK-tPA and tirofiban) 15 patients were monitored by platelet aggregometry, rapid platelet function assay (RPFA) and flow cytometry (FC). rPA alone (n = 5) caused initial increases in platelet aggregation. However, platelet aggregation was significantly (p < 0.05) and sufficiently (>80%) inhibited by abciximab/rPA (n = 5) and tirofiban/TNK-tPA (n = 5). The platelet inhibitory effect of tirofiban/TNK-tPA was more pronounced compared to abciximab/rPA with a significant difference after 2 h (p < 0.05). Tirofiban/TNK-tPA and abciximab/rPA caused decreases in platelet-leukocyte aggregates as well as in binding of specific antibodies to the platelet vitronectin receptor and P-selectin (p < 0.05, respect.). No differences among the treatment groups were seen with respect to antibody binding to MAC-1 and CD154/CD40 ligand.

CONCLUSIONS

Taken together, GP IIb/IIIa inhibitors overcome the platelet activating effect of thrombolytics resulting in sufficient platelet inhibition. RPFA is a suitable monitoring tool to accurately assess platelet inhibition. Within the given combination treatment regimen tirofiban appears to be more effective compared to abciximab and to exert effects beyond the inhibition of GP IIb/IIIa.

Absence of paradoxical thrombin activation by fibrin-specific thrombolytics in acute myocardial infarction: comparison of single-bolus tenecteplase and front-loaded alteplase

OBJECTIVES

Thrombolytic therapy in patients with acute myocardial infarction is hampered by bleeding complications and procoagulant effects favoring early reocclusion. TNK-tPA was shown in vitro to have considerable fibrin specificity. We investigated the effects of tenecteplase (TNK-tPA) and alteplase (rt-PA) on the haemostasis and fibrinolytic system.

METHODS AND RESULTS

We enrolled 30 patients with AMI into the study. Twenty patients received front-loaded rt-PA up to 100 mg; 10 patients were given TNK-tPA in a single bolus up to 50 mg. All patients received aspirin and intravenous heparin. During the first 2 days, the following parameters were repetitively determined: thrombin-antithrombin III complexes (TAT), antithrombin III (ATIII), prothrombin fragment F 1 + 2 (F 1 + 2), kallikrein-like activity (KK), activated factor XII (FXIIa), plasmin alpha 2-antiplasmin complexes (PAP), fibrinogen, D-dimers (DD), tissue-type plasminogen activator (t-PA). A total of 75 healthy persons served as control group. TAT increased significantly after rt-PA but not after TNK-tPA (3 h: 38.1 +/- 29.4 versus 10.5 +/- 4.2 microg/l; p < 0.01), indicating paradoxical thrombin activation. F 1 + 2 increased transiently after rt-PA but not after TNK-tPA. Fibrinogen was significantly lower after rt-PA versus TNK-tPA (3 h: 163 +/- 27 versus 380 +/- 54 mg/dl; p < 0.05). KK activities in the rt-PA group were significantly (p < 0.01) increased over 48 h versus TNK-tPA. PAP and D-dimers were lower over the time course of 48 h in the tenecteplase group versus rt-PA.

CONCLUSIONS

This study indicates that tenecteplase has higher fibrin specificity not only in vitro but also in vivo versus alteplase. TNK-tPA consecutively has no paradoxical systemic procoagulant effect due to the lower extent of activation of the kallikrein-factor XII system than alteplase.

Alteplase and tenecteplase: applications in the peripheral circulation

Alteplase (t-PA), a recombinant analogue of human tissue plasminogen activator, became the first genetically engineered thrombolytic approved by the Food and Drug Administration in 1987 for acute myocardial infarction (AMI). In addition to AMI, alteplase is currently approved for the treatment of acute ischemic stroke and pulmonary embolism, and we anticipate approval for catheter clearance in late 2001 in a 2-mg vial configuration. With the withdrawal of human neonatal kidney cell-derived urokinase, alteplase has become an alternative agent in peripheral vascular applications. Because few interventionalists had prior experience with the handling and dosage of alteplase, the Advisory Panel to the Society of Cardiovascular and Interventional Radiology established practice guidelines for use in noncoronary applications. Emerging clinical experience with contemporary dosing regimens shows a safety and efficacy profile similar to urokinase but with significantly reduced drug costs. Tenecteplase (TNK) is a genetically modified version of alteplase. TNK is the only plasminogen activator available that has shown a significantly enhanced safety profile versus alteplase in AMI. Approved for a 5-second, single-bolus injection in AMI, TNK possesses a longer half-life, increased resistance to plasminogen activator inhibitor, and improved fibrin specificity compared with alteplase. Because of its enhanced safety profile, TNK may be a desirable agent for peripheral vascular applications. Initial clinical studies with TNK in acute arterial and venous disease are ongoing. This article outlines the Advisory Panel guidelines for using alteplase and highlights features of tenecteplase.

Facilitated percutaneous coronary intervention for acute myocardial infarction

Facilitated percutaneous coronary intervention is a treatment strategy for acute myocardial infarction in which patients are given medications in the emergency department that open or partially open infarct-related coronary arteries. The patients are then taken to the cardiac catheterization laboratory for early angiography and angioplasty or placement of a coronary artery stent. Preliminary evidence suggests that this treatment strategy may offer outcomes similar to or better than primary angioplasty and superior to solitary fibrinolytic therapy. In addition, the treatment can be started even in hospitals that do not have primary intervention capability. Currently, large-scale clinical trials are assessing the impact of the facilitated percutaneous coronary intervention treatment strategy on the clinical outcomes of patients with acute myocardial infarction.

Platelet activation in acute myocardial infarction and the rationale for combination therapy

Current fibrinolytic regimens fail to fully restore coronary blood flow in slightly less than 50% of patients with acute myocardial infarction. Platelet activation and aggregation may be responsible for a large proportion of these therapeutic failures. Therefore, platelet inhibition may enhance thrombolysis. Experimental and early clinical evidence suggest that glycoprotein IIb/IIIa antagonists may enhance reperfusion when combined with reduced doses of thrombolytic agents. However, the clinical benefit of combination therapy will depend on the outcomes of a number large clinical trials that are currently being performed.

Effect of psychosocial factors on physiologic outcomes in patients with heart failure

Despite advances in its treatment, the epidemic of heart failure continues unabated in the United States and is escalating worldwide. The extremely high morbidity and mortality seen with heart failure demand creative approaches to this problem. Attention to nontraditional risk factors for rehospitalization and mortality, in addition to traditional medical risk factors, may yield improved outcomes. Psychosocial factors, particularly lack of social support and depression, are associated with poorer outcomes in cardiac patients. However, few studies have been conducted among patients with heart failure. In this article, the evidence relating poor quality of life, social isolation and lack of emotional support, anxiety and depression, and morbidity and mortality in patients with heart failure is discussed. Also explored are possible mechanisms for the association between psychosocial variables and physical outcomes and related clinical and research implications.