Randomized comparison of coronary thrombolysis achieved with double-bolus reteplase (recombinant plasminogen activator) and front-loaded, accelerated alteplase (recombinant tissue plasminogen activator) in patients with acute myocardial infarction. The RAPID II Investigators

Reteplase versus Alteplase for Acute Ischemic Stroke

BACKGROUND

Alteplase is the standard agent used in early reperfusion therapy, but alternative thrombolytic agents are needed. The efficacy and safety of reteplase as compared with alteplase in patients with acute ischemic stroke are unclear.

METHODS

We randomly assigned patients with ischemic stroke within 4.5 hours after symptom onset in a 1:1 ratio to receive intravenous reteplase (a bolus of 18 mg followed 30 minutes later by a second bolus of 18 mg) or intravenous alteplase (0.9 mg per kilogram of body weight; maximum dose, 90 mg). The primary efficacy outcome was an excellent functional outcome, defined as a score of 0 or 1 on the modified Rankin scale (range, 0 [no neurologic deficit, no symptoms, or completely recovered] to 6 [death]) at 90 days. The primary safety outcome was symptomatic intracranial hemorrhage within 36 hours after symptom onset.

RESULTS

A total of 707 patients were assigned to receive reteplase, and 705 were assigned to receive alteplase. An excellent functional outcome occurred in 79.5% of the patients in the reteplase group and in 70.4% of those in the alteplase group (risk ratio, 1.13; 95% confidence interval [CI], 1.05 to 1.21; P<0.001 for noninferiority and P = 0.002 for superiority). Symptomatic intracranial hemorrhage within 36 hours after disease onset was observed in 17 of 700 patients (2.4%) in the reteplase group and in 14 of 699 (2.0%) of those in the alteplase group (risk ratio, 1.21; 95% CI, 0.54 to 2.75). The incidence of any intracranial hemorrhage at 90 days was higher with reteplase than with alteplase (7.7% vs. 4.9%; risk ratio, 1.59; 95% CI, 1.00 to 2.51), as was the incidence of adverse events (91.6% vs. 82.4%; risk ratio, 1.11; 95% CI, 1.03 to 1.20).

CONCLUSIONS

Among patients with ischemic stroke within 4.5 hours after symptom onset, reteplase was more likely to result in an excellent functional outcome than alteplase. (Funded by China Resources Angde Biotech Pharma and others; RAISE ClinicalTrials.gov number, NCT05295173.).

Safety and Efficacy of Reteplase Versus Alteplase for Acute Ischemic Stroke: A Phase 2 Randomized Controlled Trial

BACKGROUND

Reteplase is a more affordable new-generation thrombolytic with a prolonged half-life. We aimed to determine the safety dose range of reteplase for patients with acute ischemic stroke within 4.5 hours of onset.

METHODS

This is a multicenter, prospective, randomized controlled, open-label, blinded-end point phase 2 clinical trial. Patients with acute ischemic stroke aged between 18 and 80 years who were eligible for standard intravenous thrombolysis were enrolled from 17 centers in China and randomly assigned (1:1:1) to receive intravenous reteplase 12+12 mg, intravenous reteplase 18+18 mg, or intravenous alteplase 0.9 mg/kg. The primary safety outcome was symptomatic intracranial hemorrhage (SITS definition) within 36 hours. The primary efficacy outcome was the proportion of patients with the National Institutes of Health Stroke Scale score of no more than 1 or a decrease of at least 4 points from the baseline at 14 days after thrombolysis.

RESULTS

Between August 2019 and May 2021, 180 patients were randomly assigned to reteplase 12+12 mg (n=61), reteplase 18+18 mg (n=67), or alteplase (n=52). Four patients did not receive the study agent. Symptomatic intracranial hemorrhage occurred in 3 of 60 (5.0%) in the reteplase 12+12 mg group, 1 of 66 (1.5%) in the reteplase 18+18 mg group, and 1 of 50 (2.0%) in the alteplase group (P=0.53). The primary efficacy outcome in the modified intention-to-treat population occurred in 45 of 60 (75.0%) in the reteplase 12+12 mg group (odds ratio, 0.85 [95% CI, 0.35-2.06]), 48 of 66 (72.7%) in the reteplase 18+18 mg group (odds ratio, 0.75 [95% CI, 0.32-1.78]), and 39 of 50 (78.0%) in alteplase group.

CONCLUSIONS

Reteplase was well tolerated in patients with acute ischemic stroke within 4.5 hours of onset in China with a similar efficacy profile to alteplase. The efficacy and appropriate dosage of reteplase for patients with acute ischemic stroke need prospective validation.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04028518.

Reteplase versus alteplase for acute ischaemic stroke within 4.5 hours (RAISE): rationale and design of a multicentre, prospective, randomised, open-label, blinded-endpoint, controlled phase 3 non-inferiority trial

BACKGROUND AND PURPOSE

Reteplase is the third generation of alternative thrombolytic agent. We hypothesis that reteplase will be non-inferior to alteplase in achieving excellent functional outcome at 90 days among eligible patients with acute ischaemic stroke.

METHODS AND DESIGN

Reteplase versus alteplase for acute ischaemic stroke within 4.5 hours (RAISE) trial is a multicentre, prospective, randomised, open-label, blinded endpoint (PROBE), controlled phase 3 non-inferiority trial. A total of 1412 eligible patients will be randomly assigned to receive either reteplase at a dose of 18 mg+ 18 mg or alteplase 0.9 mg/kg at a ratio of 1:1. An independent data monitoring committee will review the trail's progress and safety data.

STUDY OUTCOMES

The primary efficacy outcome of this study is proportion of individuals attaining an excellent functional outcome, defined as modified Rankin Scale (mRS) 0-1 at 90 days. The secondary efficacy outcomes encompass favourable functional outcome defined as mRS 0-2, major neurological improvement on the National Institutes of Health Stroke Scale, ordinal distribution of mRS and Barthel Index score of at least 95 points at 90 days. The primary safety outcomes are symptomatic intracranial haemorrhage at 36 hours within 90 days.

DISCUSSION

The RAISE trial will provide crucial insights into the selection of thrombolytic agents for stroke thrombolysis.

TRIAL REGISTRATION NUMBER

NCT05295173.

Angiographic Predictors of Viability During Intervention for a ST Elevation Myocardial Infarction

Objectives

This study aimed to identify angiographic features that would predict myocardial viability after coronary intervention for ST elevation myocardial infarction (STEMI).

Methods

This retrospective study included patients who attended Sultan Qaboos University Hospital, Muscat, Oman, between January and December 2019 with a STEMI.

Results

A total of 72 patients (61 male; mean age = 54.9 ± 12.7 years) were included in the study; 11 patients had evidence of non-viability on echocardiography. There were 13 patients with viable myocardium and 3 with non-viable myocardium who had a myocardial blush grade (MBG) of 2 or lower. Similarly, 10 patients with viability and 1 with non-viable myocardium had thrombolysis in myocardial infarction (TIMI) flow of 2 or lower in the infarct related artery (IRA). However, none of these were statistically significant. The TIMI flow in the IRA at the end of the procedure correlated with the MBG.

Conclusion

There were no clear angiographic features during primary angioplasty that could predict myocardial viability.

Application and risk prediction of thrombolytic therapy in cardio-cerebrovascular diseases: a review

Cardiocerebrovascular diseases (CVDs) are the leading cause of death worldwide, consuming huge healthcare budget. For CVD patients, the prompt assessment and appropriate administration is the crux to save life and improve prognosis. Thrombolytic therapy, as a non-invasive approach to achieve recanalization, is the basic component of CVD treatment. Still, there are risks that limits its application. The objective of this review is to give an introduction on the utilization of thrombolytic therapy in cardiocerebrovascular blockage diseases, including coronary heart disease and ischemic stroke, and to review the development in risk assessment of thrombolytic therapy, comparing the performance of traditional scales and novel artificial intelligence-based risk assessment models.

Thrombolytic Enzymes of Microbial Origin: A Review

Enzyme therapies are attracting significant attention as thrombolytic drugs during the current scenario owing to their great affinity, specificity, catalytic activity, and stability. Among various sources, the application of microbial-derived thrombolytic and fibrinolytic enzymes to prevent and treat vascular occlusion is promising due to their advantageous cost-benefit ratio and large-scale production. Thrombotic complications such as stroke, myocardial infarction, pulmonary embolism, deep venous thrombosis, and peripheral occlusive diseases resulting from blood vessel blockage are the major cause of poor prognosis and mortality. Given the ability of microbial thrombolytic enzymes to dissolve blood clots and prevent any adverse effects, their use as a potential thrombolytic therapy has attracted great interest. A better understanding of the hemostasis and fibrinolytic system may aid in improving the efficacy and safety of this treatment approach over classical thrombolytic agents. Here, we concisely discuss the physiological mechanism of thrombus formation, thrombo-, and fibrinolysis, thrombolytic and fibrinolytic agents isolated from bacteria, fungi, and algae along with their mode of action and the potential application of microbial enzymes in thrombosis therapy.

The recanalization after thrombolysis as surrogate for clinical outcomes in patients with ST-segment elevation acute myocardial infarction: A systematic review and meta-regression analysis of data from randomized controlled trials

AIMS

Thrombolytic therapy has been known to be effective in reducing clinical outcomes and increasing recanalization rate among patients with ST-segment elevation acute myocardial infarction (STEMI). However, whether post-thrombolysis recanalization could be used as a surrogate for clinical outcomes is unknown.

METHODS

We systematically searched PubMed, EMBASE and the Cochrane Library database to identify randomized controlled trials (RCT) that examined effects of thrombolytic agents in STEMI. Recanalization was defined as TIMI grade 2 or 3 flow. The primary outcome was in-hospital all-cause mortality. Secondary outcomes included in-hospital and 30-day recurrent myocardial infarction (re-MI), composite of death and re-MI, major bleeding and all bleeding. Random-effects meta-regression was used for analysis.

RESULTS

We identified 111 eligible study arms and 52 eligible comparisons from 58 RCTs involving 16 536 patients. Our analyses showed that among study arms recanalization rate was significantly inversely associated with the incidence of in-hospital all-cause mortality (β: -0.07, 95% confidence interval [CI]: -0.13 to -0.02), re-MI (β: -0.09, 95%CI: -0.18 to -0.01) and the composite of death and re-MI (β: -0.17, 95%CI: -0.28 to -0.05), and positively associated with in-hospital all bleeding but not with major bleeding. Among paired comparisons, the difference in recanalization rate was associated with the corresponding difference in incidence of in-hospital all-cause mortality (β: -0.15, 95%CI: -0.28 to -0.01) but the relationship was not significant for any other outcome.

CONCLUSION

Pooled evidence from RCTs suggest the potential use of recanalization as a surrogate for clinical outcomes in evaluating the efficacy of thrombolysis among patients with STEMI.

Angiographic outcomes in STEMI patients receiving fibrinolysis with guideline directed optimal antithrombotic therapy

STEMI is a major public health problem requiring timely reperfusion. Fibrinolysis remains prevalent reperfusion strategy where timely primary percutaneous coronary intervention (PCI) cannot be performed. Adjunctive antithrombotic agents are of utmost importance for maximizing the benefit of fibrinolysis. This prospective study evaluates the angiographic outcomes in STEMI patients receiving fibrinolysis with optimal antithrombotic therapy and reported TIMI 3 flow rates of 33.8% and 41.5% for streptokinase and reteplase respectively, that were significantly higher than various prior studies. This data reiterates the utility of thrombolysis in resource limited settings.

Inferior ST-Elevation Myocardial Infarction Presenting When Urgent Primary Percutaneous Coronary Intervention Is Unavailable: Should We Adhere to Current Guidelines?

The pivotal studies that led to the recommendations for emergent reperfusion therapy for ST-elevation myocardial infarction (STEMI) were conducted for the most part over 25 years ago. At that time, contemporary standard treatments including aspirin, statin, and even anticoagulation were not commonly used. The 2013 American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) guidelines and the 2017 European Society of Cardiology guidelines give a class I recommendation (with the level of evidence A) for primary percutaneous coronary intervention (pPCI) in patients with STEMI and ischemic symptoms of less than 12 h. However, if the patient presents to a hospital without pPCI capacity, and it is anticipated that pPCI cannot be performed within 120 min of first medical contact, fibrinolytic therapy is indicated (if there are no contraindications) (class I indication, level of evidence A). Our review of the pertinent literature shows that the current recommendation for inferior STEMI is based on the level of evidence lower than A. We can consider level B even C, supporting the recommendation for fibrinolytic therapy if pPCI is not available for inferior STEMI.

Tenecteplase Versus Reteplase in Acute Myocardial Infarction: A Network Meta-Analysis of Randomized Clinical Trials

Acute myocardial infarction (AMI) is the leading cause of death throughout the world. One of the standard approaches to treatment of AMI is fibrinolysis. The study was conducted to evaluate the clinical efficacy of tenecteplase versus reteplase through network meta-analysis for AMI. Randomized trials were comprehensively searched in PubMed, Scopus, Cochrane library, and Web of Science using appropriate strategies. Quality assessment was done for the papers. The primary and secondary end-points were mortality, TIMI grade 3 flow at 90 min, death or non-fatal stroke, infarction, total stroke and major bleeding. Odds ratios (OR) were computed (95% confidence intervals). After screening 27325 records, eight articles were included with total patients of 49875 to the meta-analysis. Indirect comparison of tenecteplase vs. reteplase showed no significant differences in the risk of mortality (OR = 0.98, p > 0.05), TIMI grade 3 flow at 90 min (OR = 0.77, p > 0.05), death or non-fatal stroke (OR = 1.04, p > 0.05), infarction (OR = 1.11, p > 0.05), total stroke (OR = 2.71, p > 0.05), and major bleeding (OR = 0.81, p > 0.05) (all p > 0.05). Indirect comparison suggests similar efficacy and safety of tenecteplase and reteplase. Hence, the use of each one of the two medicines depends on price, facility, and accessibility of the medicine.

Thrombolysis with reteplase in acute pulmonary embolism

Objective

Reteplase (recombinant plasminogen activator) is a mutant of alteplase. It has a longer half-life than its parent molecule and has shown better vessel patency rates in acute myocardial infarction. In this study, we analyzed the efficacy and safety of reteplase in acute pulmonary embolism (PE).

Methods

This observational study included patients with high- and intermediate-risk acute PE, presenting within 14 days of symptom onset. The patients were treated with reteplase, which was given in two bolus doses of 10 U each, 30 min apart, along with intravenous heparin. Patients with hemodynamic compromise (high-risk or massive PE) and normotensive patients with evidence of right ventricular (RV) dysfunction (intermediate-risk or submassive PE) on echocardiography or computed tomography were included in the study. The efficacy outcomes assessed were in-hospital death and improvement of RV function by echocardiography. The safety outcomes were major bleeding, minor bleeding, and ischemic or hemorrhagic stroke during hospitalization.

Results

Of the 40 patients included, 25% were classified as high risk with hemodynamic compromise and 75% were classified as intermediate risk. RV dysfunction was present in all the patients (100%). Concomitant lower extremity deep vein thrombosis was present in 55% of the patients. The mortality rate was 5%. There was significant improvement in RV function and reduction in pulmonary artery systolic pressure and tricuspid regurgitation severity. There was no major bleeding event or stroke, and 7.5% patients had minor extracranial bleeding.

Conclusions

Double-bolus reteplase given with heparin is effective in the treatment of high- and intermediate-risk PE, with minimal risk of bleeding.

Structural Biology and Protein Engineering of Thrombolytics

Myocardial infarction and ischemic stroke are the most frequent causes of death or disability worldwide. Due to their ability to dissolve blood clots, the thrombolytics are frequently used for their treatment. Improving the effectiveness of thrombolytics for clinical uses is of great interest. The knowledge of the multiple roles of the endogenous thrombolytics and the fibrinolytic system grows continuously. The effects of thrombolytics on the alteration of the nervous system and the regulation of the cell migration offer promising novel uses for treating neurodegenerative disorders or targeting cancer metastasis. However, secondary activities of thrombolytics may lead to life-threatening side-effects such as intracranial bleeding and neurotoxicity. Here we provide a structural biology perspective on various thrombolytic enzymes and their key properties: (i) effectiveness of clot lysis, (ii) affinity and specificity towards fibrin, (iii) biological half-life, (iv) mechanisms of activation/inhibition, and (v) risks of side effects. This information needs to be carefully considered while establishing protein engineering strategies aiming at the development of novel thrombolytics. Current trends and perspectives are discussed, including the screening for novel enzymes and small molecules, the enhancement of fibrin specificity by protein engineering, the suppression of interactions with native receptors, liposomal encapsulation and targeted release, the application of adjuvants, and the development of improved production systems.

Comparative efficacy and safety of reperfusion therapy with fibrinolytic agents in patients with ST-segment elevation myocardial infarction: a systematic review and network meta-analysis

BACKGROUND

Fibrinolytic therapy offers an alternative to mechanical reperfusion for ST-segment elevation myocardial infarction (STEMI) in settings where health-care resources are scarce. Comprehensive evidence comparing different agents is still unavailable. In this study, we examined the effects of various fibrinolytic drugs on clinical outcomes.

METHODS

We did a network meta-analysis based on a systematic review of randomised controlled trials comparing fibrinolytic drugs in patients with STEMI. Several databases were searched from inception up to Feb 28, 2017. We included only randomised controlled trials that compared fibrinolytic agents as a reperfusion therapy in adult patients with STEMI, whether given alone or in combination with adjunctive antithrombotic therapy, against other fibrinolytic agents, a placebo, or no treatment. Only trials investigating agents with an approved indication of reperfusion therapy in STEMI (streptokinase, tenecteplase, alteplase, and reteplase) were included. The primary efficacy outcome was all-cause mortality within 30-35 days and the primary safety outcome was major bleeding. This study is registered with PROSPERO (CRD42016042131).

FINDINGS

A total of 40 eligible studies involving 128 071 patients treated with 12 different fibrinolytic regimens were assessed. Compared with accelerated infusion of alteplase with parenteral anticoagulants as background therapy, streptokinase and non-accelerated infusion of alteplase were significantly associated with an increased risk of all-cause mortality (risk ratio [RR] 1·14 [95% CI 1·05-1·24] for streptokinase plus parenteral anticoagulants; RR 1·26 [1·10-1·45] for non-accelerated alteplase plus parenteral anticoagulants). No significant difference in mortality risk was recorded between accelerated infusion of alteplase, tenecteplase, and reteplase with parenteral anticoagulants as background therapy. For major bleeding, a tenecteplase-based regimen tended to be associated with lower risk of bleeding compared with other regimens (RR 0·79 [95% CI 0·63-1·00]). The addition of glycoprotein IIb or IIIa inhibitors to fibrinolytic therapy increased the risk of major bleeding by 1·27-8·82-times compared with accelerated infusion alteplase plus parenteral anticoagulants (RR 1·47 [95% CI 1·10-1·98] for tenecteplase plus parenteral anticoagulants plus glycoprotein inhibitors; RR 1·88 [1·24-2·86] for reteplase plus parenteral anticoagulants plus glycoprotein inhibitors).

INTERPRETATION

Significant differences exist among various fibrinolytic regimens as reperfusion therapy in STEMI and alteplase (accelerated infusion), tenecteplase, and reteplase should be considered over streptokinase and non-accelerated infusion of alteplase. The addition of glycoprotein IIb or IIIa inhibitors to fibrinolytic therapy should be discouraged.

FUNDING

None.

Co-ordinated spatial propagation of blood plasma clotting and fibrinolytic fronts

Fibrinolysis is a cascade of proteolytic reactions occurring in blood and soft tissues, which functions to disintegrate fibrin clots when they are no more needed. In order to elucidate its regulation in space and time, fibrinolysis was investigated using an in vitro reaction-diffusion experimental model of blood clot formation and dissolution. Clotting was activated by a surface with immobilized tissue factor in a thin layer of recalcified blood plasma supplemented with tissue plasminogen activator (TPA), urokinase plasminogen activator or streptokinase. Formation and dissolution of fibrin clot was monitored by videomicroscopy. Computer systems biology model of clot formation and lysis was developed for data analysis and experimental planning. Fibrin clot front propagated in space from tissue factor, followed by a front of clot dissolution propagating from the same source. Velocity of lysis front propagation linearly depended on the velocity clotting front propagation (correlation r2 = 0.91). Computer model revealed that fibrin formation was indeed the rate-limiting step in the fibrinolysis front propagation. The phenomenon of two fronts which switched the state of blood plasma from liquid to solid and then back to liquid did not depend on the fibrinolysis activator. Interestingly, TPA at high concentrations began to increase lysis onset time and to decrease lysis propagation velocity, presumably due to plasminogen depletion. Spatially non-uniform lysis occurred simultaneously with clot formation and detached the clot from the procoagulant surface. These patterns of spatial fibrinolysis provide insights into its regulation and might explain clinical phenomena associated with thrombolytic therapy.

The evolution of recombinant thrombolytics: Current status and future directions

Cardiovascular disorders are on the rise worldwide due to alcohol abuse, obesity, hypertension, raised blood lipids, diabetes and age-related risks. The use of classical antiplatelet and anticoagulant therapies combined with surgical intervention helped to clear blood clots during the inceptive years. However, the discovery of streptokinase and urokinase ushered the way of using these enzymes as thrombolytic agents to degrade the fibrin network with an issue of systemic hemorrhage. The development of second generation plasminogen activators like anistreplase and tissue plasminogen activator partially controlled this problem. The third generation molecules, majorly t-PA variants, showed desirable properties of improved stability, safety and efficacy with enhanced fibrin specificity. Plasmin variants are produced as direct fibrinolytic agents as a futuristic approach with targeted delivery of these drugs using liposome technlogy. The novel molecules from microbial, plant and animal origin present the future of direct thrombolytics due to their safety and ease of administration.

Fibrin(ogen)olytic and antiplatelet activities of a subtilisin-like protease from Solanum tuberosum (StSBTc-3)

Plant serine proteases have been widely used in food science and technology as well as in medicine. In this sense, several plant serine proteases have been proposed as potential anti-coagulants and anti-platelet agents. Previously, we have reported the purification and identification of a plant serine protease from Solanum tuberosum leaves. This potato enzyme, named as StSBTc-3, has a molecular weight of 72 kDa and it was characterized as a subtilisin like protease. In this work we determine and characterize the biochemical and medicinal properties of StSBTc-3. Results obtained show that, like the reported to other plant serine proteases, StSBTc-3 is able to degrade all chains of human fibrinogen and to produces fibrin clot lysis in a dose dependent manner. The enzyme efficiently hydrolyzes β subunit followed by partially hydrolyzed α and γ subunits of human fibrinogen. Assays performed to determine StSBTc-3 substrate specificity using oxidized insulin β-chain as substrate, show seven cleavage sites: Asn3-Gln4; Cys7-Gly8; Glu13-Ala14; Leu15-Tyr16; Tyr16-Leu17; Arg22-Gly23 and Phe25-Tyr26, all of them were previously reported for other serine proteases with fibrinogenolytic activity. The maximum StSBTc-3 fibrinogenolytic activity was determined at pH 8.0 and at 37 C. Additionally, we demonstrate that StSBTc-3 is able to inhibit platelet aggregation and is unable to exert cytotoxic activity on human erythrocytes in vitro at all concentrations assayed. These results suggest that StSBTc-3 could be evaluated as a new agent to be used in the treatment of thromboembolic disorders such as strokes, pulmonary embolism and deep vein thrombosis.

A novel model for evaluating thrombolytic therapy in dogs with ST-elevation myocardial infarction

Background

There is still no standard large animal model for evaluating the effectiveness of potential thrombolytic therapies. Here, we aimed to develop a new beagle model with ST-elevation myocardial infarction (STEMI) by injecting autologous emboli with similar components of coronary thrombus.

Methods

18 male beagles were included and divided into three groups: red embolus group (n = 6), white embolus group (n = 6) or white embolus + rt-PA group (n = 6). Autologous emboli were infused into the mid-distal region of the left anterior descending coronary artery. The composition of embolus was examined by scanning electron microscope (SEM). Coronary angiography was performed to verify the status of embolism. Myocardial infarct size was measured by 2, 3, 5- triphenyltetrazolium chloride (TTC) staining.

Results

Red thrombus was characteristic of loose reticular structure of erythrocytes under SEM, while the white embolus had compacted structure that mainly consisted of a dense mass of fibrin. Coronary angiography showed the recanalization rate was 2/6 in the red embolus group versus 0/6 in the white embolus group in three hours after occlusion. Arrhythmia, resolution of ST-segment elevation and lower T wave on the electrocardiogram appeared in the red embolus group but not in the white embolus group. Another six dogs with white thrombi were treated with rt-PA. Five out of six dogs exhibited coronary recanalization after two hours of therapy, compared to zero dogs without rt-PA treatment. The size of myocardial infarction in rt-PA group reduced significantly compared with white embolus group using TTC staining method.

Conclusions

The white embolism model was more convenient experimentally and had a higher uniformity, stability and success rate. The major innovation of our study is that we applied fibrin-rich white thrombi to establish beagle model possessing features of clinically observed coronary thrombi in time window of intravenous thrombolysis of STEMI. This model can be used to evaluate new thrombolytic drugs for the treatment of STEMI.

The pattern and risk factors associated with adverse drug reactions induced by Reteplase in patients with acute ST-elevation myocardial infarction: The first report from Iranian population

Objective:

Acute myocardial infarction (AMI) is one of the main leading causes of mortality and morbidity. Reteplase is a fibrin-specific thrombolytic which is used in the treatment of AMI. There is a limited number of studies reporting the postmarketing adverse drug reactions (ADRs) induced by reteplase. This study was aimed to examine the reteplase pattern of ADR and its associated risk factors in patients with acute ST-elevation myocardial infarction.

Methods:

A cross-sectional, prospective study in an 8-month period was done at the University affiliated referral cardiovascular center. The Naranjo probability scale and World Health Organization criteria for severity of ADRs were used for assessing the ADRs. The linear regression and logistic regression tests were used to evaluate the correlation between ADRs and risk factors.

Findings:

The all 20 patients who received reteplase during the study period were entered. The majority of patients (n = 17) experienced at least one ADR. The results showed that the incidence of ADRs was mainly associated with gender and age, and the number of ADRs was associated with the history of diabetes and taking anti-diabetic agents. The gender was the main predictor in the occurrence of ADRs (odds ratio: 32, 95% confidence interval: 1.38–737.45; P = 0.030).

Conclusion:

The results showed that gender, age, diabetes mellitus, and using of anti-diabetes medications are the risk factors associated with the incidence of ADRs by reteplase.

Enzymes approved for human therapy: indications, mechanisms and adverse effects

Research and drug developments fostered under orphan drug product development programs have greatly assisted the introduction of efficient and safe enzyme-based therapies for a range of rare disorders. The introduction and regulatory approval of 20 different recombinant enzymes has enabled, often for the first time, effective enzyme-replacement therapy for some lysosomal storage disorders, including Gaucher (imiglucerase, taliglucerase, and velaglucerase), Fabry (agalsidase alfa and beta), and Pompe (alglucosidase alfa) diseases and mucopolysaccharidoses I (laronidase), II (idursulfase), IVA (elosulfase), and VI (galsulfase). Approved recombinant enzymes are also now used as therapy for myocardial infarction (alteplase, reteplase, and tenecteplase), cystic fibrosis (dornase alfa), chronic gout (pegloticase), tumor lysis syndrome (rasburicase), leukemia (L-asparaginase), some collagen-based disorders such as Dupuytren's contracture (collagenase), severe combined immunodeficiency disease (pegademase bovine), detoxification of methotrexate (glucarpidase), and vitreomacular adhesion (ocriplasmin). The development of these efficacious and safe enzyme-based therapies has occurred hand in hand with some remarkable advances in the preparation of the often specifically designed recombinant enzymes; the manufacturing expertise necessary for commercial production; our understanding of underlying mechanisms operative in the different diseases; and the mechanisms of action of the relevant recombinant enzymes. Together with information on these mechanisms, safety findings recorded so far on the various adverse events and problems of immunogenicity of the recombinant enzymes used for therapy are presented.

Management of adjunctive antithrombotic therapy in STEMI patients treated with fibrinolysis undergoing rescue or delayed PCI

Although primary percutaneous coronary intervention (PCI) is the recommended method of reperfusion in patients presenting with ST-segment elevation myocardial infarction (STEMI), fibrinolysis remains a beneficial alternative in patients who cannot be reperfused timely with primary PCI, and is still the preferred revascularisation strategy in many parts of the world where PCI facilities are unavailable. Because fibrinolysis is known to activate platelets and promote thrombin activity, concomitant administration of antiplatelet and anticoagulant therapies is needed to lower the risk for re-occlusion and to support mechanical interventions in patients undergoing rescue or delayed PCI. However, the addition of oral antiplatelet and parenteral anticoagulant drugs on top of fibrinolysis may come at the price of an increased risk of bleeding. The current availability of several antiplatelet and anticoagulant therapies often leads to questions about the optimal selection in STEMI patients treated with fibrinolytics. This article appraises current evidences for the management of adjunctive antiplatelet and anticoagulant therapies in patients with STEMI undergoing fibrinolysis followed by rescue or delayed PCI.

Cost-Effectiveness of Thrombolytic Therapy, Compared with Anticoagulants Therapy in the Treatment of Acute Myocardial Infarction in Albania

AIM: The study aim is to evaluate the cost-effectiveness of thrombolytic treatment in acute MI comparing with anticoagulants therapy and between each other thrombolytic (SK, r-Pa).MATERIAL AND METHODS: We used a prospective registry of all patients admitted for acute myocardial infarction in intensive care units in Tirana. The average drugs cost was calculated for the hospitalization period in Albanian money (ALL). Survival and life quality were estimated by phone contact 1 year after acute MI.RESULTS: Anticoagulant group cost is 23865.3 ALL (170.5€), SK group cost is 54148.63 ALL (386.7€), r-Pa group has a cost of 92184.90 ALL (658.5€). In the group treated with SK the hospital survival is 100%, while in the control group 88.8%. Reteplase group has a lower period of stay in hospital than SK group 13.04 days vs. 17.97 days, mean age in group treated with r-Pa is 64.29 ± 10.03 approximate with anticoagulant group mean age 64.17 ± 11.08; differ significantly with SK group mean age 56.75 ± 10.04. Survival after 1 year was 96.4% for r-Pa and 96.9% SK.CONCLUSIONS: SK and r-Pa are successful thrombolytics with high effectiveness. It is gained a higher survival with the thrombolytic treatments. Reteplase is well tolerated in older patients than SK, is easier to apply than Streptokinase, but has higher cost.

Meta-analysis of randomized phase II trials to inform subsequent phase III decisions

BACKGROUND

If multiple Phase II randomized trials exist then meta-analysis is favorable to increase statistical power and summarize the existing evidence about an intervention's effect in order to help inform Phase III decisions. We consider some statistical issues for meta-analysis of Phase II trials for this purpose, as motivated by a real example involving nine Phase II trials of bolus thrombolytic therapy in acute myocardial infarction with binary outcomes.

METHODS

We propose that a Bayesian random effects logistic regression model is most suitable as it models the binomial distribution of the data, helps avoid continuity corrections, accounts for between-trial heterogeneity, and incorporates parameter uncertainty when making inferences. The model also allows predictions that inform Phase III decisions, and we show how to derive: (i) the probability that the intervention will be truly beneficial in a new trial, and (ii) the probability that, in a new trial with a given sample size, the 95% credible interval for the odds ratio will be entirely in favor of the intervention. As Phase II trials are potentially optimistic due to bias in design and reporting, we also discuss how skeptical prior distributions can reduce this optimism to make more realistic predictions.

RESULTS

In the example, the model identifies heterogeneity in intervention effect missed by an I-squared of 0%. Prediction intervals accounting for this heterogeneity are shown to support subsequent Phase III trials. The probability of success in Phase III trials increases as the sample size increases, up to 0.82 for intracranial hemorrhage and 0.79 for reinfarction outcomes.

CONCLUSIONS

The choice of meta-analysis methods can influence the decision about whether a trial should proceed to Phase III and thus need to be clearly documented and investigated whenever a Phase II meta-analysis is performed.

Diastolic Timed Vibrator: Noninvasive Pre-Hospitalization Treatment of Acute Coronary Ischemia

The speed of intervention is one of the major factors in increasing the survival rate of patients suffering from acute coronary ischemia. The two principal techniques currently in use: pharmacological and interventional, can be employed to re-canalize coronary arteries, but the former is slow acting and often leads to incomplete reperfusion, while the latter requires specialized personnel in a hospital with a cardiac catheterization laboratory. In this paper, we introduce a novel method intended for pre-hospitalization treatment of patients with acute coronary ischemia that can be safely applied by a minimally trained individual prior to or during patient transportation to hospital. It consists in applying low frequency mechanical vibrations to the left intercostal space of patient's chest during diastole of the heart cycle, to induce vibrations of the heart and thus of the coronary arteries. Mechanical vibrations stimulate mixing of blood which improves drug delivery to the occlusion site, applies mechanical force on the clot leading to its faster dissolution and finally acts as a strong vasodilator in case of spasms. We introduce the principle of operation and the architecture of the Diastolic Timed Vibrator (DTV), including a custom ECG processing algorithm, vibration pattern generator and active braking methods. Experimental results demonstrate the functionality of the DTV device and pave way for in-vivo tests necessary for clinical confirmation of the proposed method.

Comparison of in-hospital outcomes with low-dose fibrinolytic therapy followed by urgent percutaneous coronary intervention versus percutaneous coronary intervention alone for treatment of ST-elevation myocardial infarction

In patients with acute ST-elevation myocardial infarction (STEMI), a strategy of prehospital reduced dose fibrinolytic administration coupled with urgent percutaneous coronary intervention (PCI), termed FAST-PCI strategy, has been found to be superior to primary PCI (PPCI) alone. A coordinated STEMI system of care that includes FAST-PCI should offer better outcomes than a system in which prehospital diagnosis of STEMI is followed by PPCI alone. The aim of this study was to compare the in-hospital outcomes for patients treated with the FAST-PCI approach with outcomes for patients treated with the PPCI approach in a common system. The in-hospital data for 253 STEMI patients (March 2003-December 2009) treated with a FAST-PCI protocol were compared with 124 patients (January 2010-August 2011) treated with PPCI strategy alone. In-hospital mortality was the primary comparator. Stroke, major bleeding, and reinfarction during index hospitalization were also compared. The in-hospital mortality was significantly lower with FAST-PCI than with PPCI (2.77% vs 10.48%, p = 0.0017). Rates of stroke, reinfarction, and major bleeding were similar in the 2 groups. There was a lower frequency of pre-PCI Thrombolysis In Myocardial Infarction 0 flow (no patency) seen in patients treated with FAST-PCI compared with the PPCI patients (26.7% vs 62.7%, p <0.0001). Earlier infarct artery patency in the FAST-PCI group had a favorable impact on the incidence of cardiogenic shock on hospital arrival (3.1% vs 20.9%, p <0.0001). In conclusion, compared with a PPCI strategy in a common STEMI system of care, the FAST-PCI strategy was associated with earlier infarct artery patency and lower incidence of cardiogenic shock, as well as with reduced in-hospital mortality.

Impact of type of thrombolytic agent on in-hospital outcomes in ST-segment elevation myocardial infarction patients in the Middle East

Little is known about the impact of thrombolytic agents on in-hospital outcomes in the Middle East. The objective of this study was to evaluate the impact of thrombolytic agents on in-hospital outcomes in ST-segment elevation myocardial infarction (STEMI) patients in six Middle Eastern countries. Gulf Registry of Acute Coronary Events was a prospective, multinational, multicentre, observational survey of consecutive acute coronary syndrome patients admitted to 65 hospitals in 2006 and 2007. Out of 1,765 STEMI patients admitted to hospitals within 12 h of symptoms onset, 25, 43, and 30% were treated with streptokinase, reteplase, and tenecteplase, respectively. Median age of the study cohort was 50 (45-59) years and majority were males (89%). The overall median symptom onset-to-presentation and median door-to-needle times were 130 min (65-240) and 45 min (30-75), respectively. Streptokinase patients had worse GRACE risk scores compared to patients who received fibrin specific thrombolytics. Academic hospitals and cardiologists as admitting physicians were associated with the use of fibrin specific thrombolytics. After significant covariate adjustment, both reteplase [odds ratio (OR), 0.38; 95% CI: 0.18-0.79; P = 0.009] and tenecteplase (OR, 0.30; 95% CI: 0.12-0.77; P = 0.012) were associated with lower all-cause in-hospital mortality compared with streptokinase. No significant differences in other in-hospital outcomes were noted between the thrombolytic agents. In conclusion, in light of the study's limitations, fibrin specific agents, reteplase and tenecteplase, were associated with lower all-cause in-hospital mortality compared to the non-specific fibrin agent, streptokinase. However, the type of thrombolytic agent used did not influence other in-hospital outcomes.

Optimal Anticoagulant Therapy in ST Elevation Myocardial Infarction Interventions

Bivalirudin is a direct thrombin inhibitor. It is a new recommendation for the treatment of patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention. Bivalirudin combined with aspirin and P2Y₁₂ inhibitors has proved to be an effective and safe choice for the management of thrombus in coronary artery disease. The use of bivalirudin compared with the combination of heparin plus glycoprotein IIb/IIIa inhibitors as anticoagulant therapy is associated with reduced severe bleeding and inpatient mortality, as well as diminished costs. There is only a slight increase of late stent thrombosis, which may be controlled with the use of thienopyridines.

Newer Pharmaceutical Agents for STEMI Interventions

ST-elevation myocardial infarction (STEMI) causes 12.6% of deaths worldwide. Treatment strategies involve early revascularization by percutaneous coronary intervention and/or fibrinolytics, with adjunctive pharmacologic therapy. While antiplatelet therapy remains the cornerstone of pharmacologic management, newer antithrombotic therapies are showing benefit in the reduction of long-term thrombotic events following acute vessel occlusion. Future directions in adjunctive STEMI management include the use of hematopoietic stem cell therapy or growth factors to induce proliferation and differentiation of cardiac myocytes.

Clinical Profile and Mortality of ST-Segment Elevation Myocardial Infarction Patients Receiving Thrombolytic Therapy in the Middle East

Objective:

Little is known about thrombolytic therapy patterns in patients with ST-elevation myocardial infarction (STEMI) in the Middle East. The objective of this study was to evaluate the clinical profile and mortality of STEMI patients who arrived in hospital within 12 hours from pain onset and received thrombolytic therapy.

Patients and Methods:

This was a prospective, multinational, multi-centre, observational survey of consecutive acute coronary syndrome patients admitted to 65 hospitals in six Middle Eastern countries during the period between October 2008 and June 2009, as part of Gulf RACE-II (Registry of Acute Coronary Events). Analyses were performed using univariate statistics.

Results:

Out of 2,465 STEMI patients, 66% (n = 1,586) were thrombolysed with namely: streptokinase (43%), reteplase (44%), tenecteplase (10%), and alteplase (3%). 22.7% received no reperfusion. Median age of the study cohort was 50 (45-59) years with majority being males (91%). The overall median symptom onset-to-presentation and door-to-needle times were 165 (95- 272) minutes and 38 (24-60) minutes, respectively. Generally, patients presenting with higher GRACE risk scores were treated with newer thrombolytic agents (reteplase and tenecteplase) (P < 0.001). The use of newer thrombolytic agents was associated with a significantly lower mortality at both 1-month (0.8% vs. 1.7% vs. 4.2%; P = 0.014) and 1-year (0% vs. 1.7% vs. 3.4%; P = 0.044) compared to streptokinase use.

Conclusions:

Majority of STEMI patients from the Middle East were thrombolysed with streptokinase and reteplase in equal numbers. Nearly one-fifth of patients did not receive any reperfusion therapy. There was inappropriately long symptom-onset to hospital presentation as well as door-to-needle times. Use of newer thrombolytic agents in high risk patients was appropriate. Newer thrombolytic agents were associated with significantly lower mortality at 1-month and 1-year compared to the older agent, streptokinase.

Coronary collateral circulation: Effects on outcomes of acute anterior myocardial infarction after primary percutaneous coronary intervention

Background

To investigate the effects of collateral coronary circulation on the outcome of the patients with anterior myocardial infarction (MI) with left anterior desending artery occlusion abruptly.

Methods

Data of 189 patients with acute anterior MI who had a primary percutaneous coronary intervention (PCI) in the first 12 h from the onset of symptoms between January 2004 and December 2008 were retrospective analyzed. Left anterior descending arteries (LAD) of all patients were occluded. LADs were reopened with primary PCI. According to the collateral circulation, all patients were classified to two groups: no collateral group (n = 111), patients without angiographic collateral filling of LAD or side branches (collateral index 0) and collateral group (n = 78), and patients with angiographic collateral filling of LAD or side branches (collateral index 1, 2 or 3). At one year's follow-up, the occurrence of death, reinfarction, stent thrombosis (ST), target vessel revascularization and readmission because of heart failure were observed.

Results

At one year, the mortality was lower in patients with collateral circulation compared with those without collateral circulation (1% vs. 8%, P = 0.049), whereas there were no differences in the occurrence of reinfarction, ST, target vessel revascularization and readmission because of heart failure. The occurrence of composite of endpoint was lower in patients with collateral circulation compared with those without collateral circulation (12% vs. 26%; P = 0.014).

Conclusions

Pre-exist collateral circulation may prefigure the satisfactory prognosis to the patients with acute anterior MI after primary PCI in the first 12 h of MI onset.

Serine-proteases as plasminogen activators in terms of fibrinolysis

OBJECTIVES

This review should give an overview about the natural human plasminogen activators and their various modified variants as well as similar substances isolated from animals, microorganisms and plants. When a blood clot is formed in a blood vessel, it avoids the oxygen supply of the surrounding tissue. A fast fibrinolytic therapy should redissolve the blood vessel and reduce the degradation of the tissue. All proteases that are part of the human blood coagulation and fibrinolytic system belong to the serine protease family. t-PA (tissue plasminogen activator) and u-PA (urokinase plasminogen activator) are the naturally occurring fibrinolytic agents that are also used in therapy.

KEY FINDINGS

Despite many years of research, t-PA is still the gold standard in fibrinolytic therapy. But it has to be given as an infusion, which needs time. Modified fibrinolytic substances are, were, or perhaps will be in the market. They have different advantages over t-PA, but often the disadvantages predominate.

CONCLUSION

Many substances have been developed but an optimal fibrinolytic agent combined with a simple administration is not in therapeutic use to date.

Differentiating pharmacologic agents used in catheter-directed thrombolysis

The use of catheter-directed thrombolysis is a proven treatment for arterial ischemia, deep vein thrombosis, and severe pulmonary embolism. For arterial ischemia, thrombolysis has resulted in improved amputation-free survival and fewer subsequent surgeries to reestablish blood flow to the ischemic limb. The management of patients with thromboembolic diseases is complex, and the multiple thrombolytic drugs available to choose from compound this complexity. Although some believe the available thrombolytic agents are interchangeable, real biochemical differences exist that may prove otherwise. This article describes these pharmacologic differences and how they may affect the clinical practice of catheter-directed thrombolysis.

Proteases as therapeutics

Proteases are an expanding class of drugs that hold great promise. The U.S. FDA (Food and Drug Administration) has approved 12 protease therapies, and a number of next generation or completely new proteases are in clinical development. Although they are a well-recognized class of targets for inhibitors, proteases themselves have not typically been considered as a drug class despite their application in the clinic over the last several decades; initially as plasma fractions and later as purified products. Although the predominant use of proteases has been in treating cardiovascular disease, they are also emerging as useful agents in the treatment of sepsis, digestive disorders, inflammation, cystic fibrosis, retinal disorders, psoriasis and other diseases. In the present review, we outline the history of proteases as therapeutics, provide an overview of their current clinical application, and describe several approaches to improve and expand their clinical application. Undoubtedly, our ability to harness proteolysis for disease treatment will increase with our understanding of protease biology and the molecular mechanisms responsible. New technologies for rationally engineering proteases, as well as improved delivery options, will expand greatly the potential applications of these enzymes. The recognition that proteases are, in fact, an established class of safe and efficacious drugs will stimulate investigation of additional therapeutic applications for these enzymes. Proteases therefore have a bright future as a distinct therapeutic class with diverse clinical applications.

Warfarin and fibrinolysis--a challenging combination: an observational cohort study

Background

Patients presenting with ST-segment elevation myocardial infarction (STEMI) frequently use warfarin. Fibrinolytic agents and warfarin both increase bleeding risk, but only a few studies have been published concerning the bleeding risk of warfarin-prescribed patients receiving fibrinolysis. The objective of this study was to define the prevalence for intracranial haemorrhage (ICH) or major bleeding in patients on warfarin treatment receiving pre-hospital fibrinolysis.

Methods

This was an observational cohort study. Data for this retrospective case series were collected in Helsinki Emergency Medical Service catchment area from 1.1.1997 to 30.6.2010. All warfarin patients with suspected ST-segment elevation myocardial infarction (STEMI), who received pre-hospital fibrinolysis, were included. Bleeding complications were detected from Medical Records and classified as ICH, major or minor bleeding.

Results

Thirty-six warfarin patients received fibrinolysis during the study period. Fourteen patients had bleeding complications. One (3%, 95% CI 0-15%) patient had ICH, six (17%, 95% CI 7-32%) had major and seven (19%, 95% CI 9-35%) had minor bleeding. The only fatal bleeding occurred in a patient with ICH. Patients' age, fibrinolytic agent used or aspirin use did not predispose to bleeding complications. High International Normalized Ratio (INR) seemed to predispose to bleedings with values over 3, but no statistically significant difference was found.

Conclusions

Bleedings occur frequently in warfarin patients treated with fibrinolysis in the real world setting, but they are rarely fatal.

Thrombolytics and myocardial infarction

Coronary artery disease is the single leading cause of death in the United States. Occlusion of the coronary artery was identified to be the cause of myocardial infarction almost a century ago. Following a series of investigations, streptokinase was discovered and demonstrated to be beneficial for the treatment of patients with acute myocardial infarction in terms of reducing short- and long-term mortality. Newer agents including tissue plasminogen activators such as alteplase, reteplase, tenecteplase were developed subsequently. In the present era, thrombolytic therapy and primary percutaneous coronary intervention has revolutionized the way patients with acute myocardial infarction are managed resulting in significant reduction in cardiovascular death. This article provides an overview of the various thrombolytic agents utilized in the management of patients with acute myocardial infarction.

Thrombolysis with reteplase, an unglycosylated plasminogen activator variant, in experimental embolic stroke

We incorporated diffusion-weighted magnetic resonance imaging (MRI) (DWI) and perfusion-weighted MRI (PWI) to evaluate the efficacy of thrombolysis in experimental embolic stroke using a plasminogen activator, reteplase. Reteplase (rPA) is an unglycosylated plasminogen activator with enhanced fibrinolytic potency. Right internal carotid arteries of 34 rabbits were embolized using aged heterologous thrombi. Baseline DWI and PWI scans 0.5 hours after embolization confirmed successful embolization among 32. Intravenous treatment with rPA (n=11; 1 mg/kg bolus), recombinant tissue plasminogen activator (rt-PA) (n=11; 6 mg/kg bolus over 1 hour), or placebo (n=10) commenced 1 hour after stroke induction. MRIs were performed at 1.75, 3, and 5 hours after embolization. Six hours after embolization, brains were harvested and examined for hemorrhage. Posttreatment areas of diffusion abnormality and perfusion delay were graded using both a semiquantitative scale and percent areas expressed as a ratio of the baseline values. Improved perfusion was seen among the rt-PA, and rPA-treated groups compared with placebo, using a semiquantitative scale (P<.01 rt-PA v controls, P<.05, rPA v controls). DWI scans, however, were not improved with thrombolysis. Cerebral hemorrhage was not increased with thrombolytic treatment, although the incidence of wound site hemorrhage was higher with either rPA or rt-PA. One fatal systemic hemorrhage was observed in each of the thrombolytic-treated groups. Cerebral perfusion was equally improved with either rt-PA or rPA without causing excess cerebral hemorrhage. An advantage of rPA is single-bolus dosing rather than continuous infusion. Use of rPA for stroke treatment should be further explored.

Optimizing the use of thrombolytics in ST-segment elevation myocardial infarction

The advent of thrombolytic therapy was a major advance in the treatment of ST-segment elevation myocardial infarction (STEMI). The administration of fibrinolytic reperfusion therapy can reduce mortality rates by as much as 30%, with the greatest benefit observed if therapy is administered soon after symptom onset. Outcomes with thrombolytic therapy are improved if there is adjunctive treatment with aspirin, clopidogrel and an anti-thrombin agent. Although there is evidence that primary percutaneous coronary intervention (PCI) is the most effective reperfusion strategy, the majority of hospitals still do not have PCI capabilities and, thus, thrombolytic therapy remains a cornerstone of treatment for STEMI. Trials of thrombolytic therapy have demonstrated that initial patency rates can approach 85%, but there is still a need for improvement of non-invasive markers that predict failure or re-occlusion of the infarct-related artery. Because of the overwhelming data demonstrating the importance of rapid reperfusion, current studies are examining the role of earlier treatment of patients with STEMI via pre-hospital administration and/or coordinated systems for rapid diagnosis, transfer and delivery of definitive care. Facilitated PCI, a strategy of thrombolytic therapy followed by immediate PCI, has not been shown to be beneficial and current studies are examining the optimal timing of coronary angiography after thrombolytic therapy.

The impact of initial treatment delay using primary angioplasty on mortality among patients with acute myocardial infarction: from the Korea acute myocardial infarction registry

The impact of treatment delays to reperfusion on patient mortality after primary percutaneous coronary intervention (PCI) for ST elevation myocardial infarction (STEMI) is controversial. We analyzed 5,069 patients included in the Korea Acute Myocardial Infarction Registry (KAMIR) between November 2005 and January 2007. We selected 1,416 patients who presented within 12 hr of symptom onset and who were treated with primary PCI. The overall mortality at one month was 4.4%. The medians of door-to-balloon time, symptom onset-to-balloon time, and symptom onset-to-door time were 90 (interquartile range, 65-136), 274 (185-442), and 163 min (90-285), respectively. One-month mortality was not increased significantly with any increasing delay in door-to-balloon time (4.3% for < or =90 min, 4.4% for >90 min; p=0.94), symptom onset-to-balloon time (3.9% for < or =240 min, 4.8% for >240 min; p=0.41), and symptom onset-to-door time (3.3% for < or =120 min, 5.0% for >120 min; p=0.13). These time variables had no impact on one-month mortality in any subgroup. Thus, this first nationwide registry data in Korea showed a good result of primary PCI, and the patient prognosis may not depend on the initial treatment delay using the current protocols.

Accelerated streptokinase in ST-elevation myocardial infarction — a romanian (ASK–ROMANIA) multicenter registry

BACKGROUND

The classical streptokinase regimen (1.5 M.U. over 60 min) may be too slow in patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVE

To compare the efficacy and safety of four streptokinase regimens in STEMI patients.

METHODS

1880 consecutive patients admitted within 6 h of STEMI onset were allocated one of the following four streptokinase regimens: 1.5 M.U. over 60 min (n=517); 1.5 M.U./30 min (n=355); 1.5 M.U./20 min (n=507); 0.75 M.U./10 min, repeated or not after 50 min if no electrocardiographic criteria of reperfusion (n=501).

RESULTS

Rates of coronary reperfusion (non-invasively detected) for SK1.5/30 (72.39%), SK1.5/20 (75.34%) and SK0.75/10 (72.85%) were similar and higher than for SK1.5/60 (64.03%, p=0.019, p<0.0001, and p=0.006, respectively). In-hospital mortality was significantly lower for SK1.5/20 (7.10%) and SK0.75/10 (7.38%) and at the limit of significance for SK1.5/30 (7.60%) compared with SK1.5/60 (11.60%, p<0.0001, 0.006, and 0.053, respectively). Intracerebral haemorrhage and other major bleeding had similar incidence in the four groups.

CONCLUSIONS

Compared to the classical 1.5 M.U. over 60 min streptokinase regimen, significantly higher rates of coronary reperfusion and lower in-hospital mortality can be obtained by infusing the same dose over only 20 min, or either one or two half doses over only 10 min, without risk increase.

Reperfusion strategies in acute ST-segment elevation myocardial infarction: a comprehensive review of contemporary management options

There are an estimated 500,000 ST-segment elevation myocardial infarction (STEMI) events in the U.S. annually. Despite improvements in care, up to one-third of patients presenting with STEMI within 12 h of symptom onset still receive no reperfusion therapy acutely. Clinical studies indicate that speed of reperfusion after infarct onset may be more important than whether pharmacologic or mechanical intervention is used. Primary percutaneous coronary intervention (PCI), when performed rapidly at high-volume centers, generally has superior efficacy to fibrinolysis, although fibrinolysis may be more suitable for many patients as an initial reperfusion strategy. Because up to 70% of STEMI patients present to hospitals without on-site PCI facilities, and prolonged door-to-balloon times due to inevitable transport delays commonly limit the benefit of PCI, the continued role and importance of the prompt, early use of fibrinolytic therapy may be underappreciated. Logistical complexities such as triage or transportation delays must be considered when a reperfusion strategy is selected, because prompt fibrinolysis may achieve greater benefit, especially if the fibrinolytic-to-PCI time delay associated with transfer exceeds approximately 1 h. Selection of a fibrinolytic requires consideration of several factors, including ease of dosing and combination with adjunctive therapies. Careful attention to these variables is critical to ensuring safe and rapid reperfusion, particularly in the prehospital setting. The emerging modality of pharmacoinvasive therapy, although controversial, seeks to combine the benefits of mechanical and pharmacologic reperfusion. Results from ongoing clinical trials will provide guidance regarding the utility of this strategy.

Reperfusion strategies for ST-elevation myocardial infarction

Management of ST-elevation myocardial infarction requires rapid, sustained and early restoration of flow in the infarct-related artery to minimize myocardial damage and to improve clinical outcomes. Primary percutaneous coronary intervention (PCI) is the preferred therapy but is limited by restricted availability and delays in implementation. Fibrinolytic administration is widely available but is limited by its failure to achieve Thrombolysis in Myocardial Infarction grade 3 flow in many patients, re-infarction, and intracranial hemorrhage. A combination approach to reperfusion--facilitated PCI--involves the administration of a pharmacologic agent to improve reperfusion with PCI. The evidence supporting facilitated PCI varies according to the pharmacologic regimen at this time.

Reperfusion strategies in the emergency treatment of ST-segment elevation myocardial infarction

Prompt restoration of blood flow is the primary treatment goal in ST-segment elevation myocardial infarction to optimize clinical outcomes. The ED plays a critical role in rapid triage, diagnosis, and management of ST-elevation myocardial infarction, and in the decision about which of the 2 recommended reperfusion options, that is, pharmacologic and mechanical (catheter-based) strategies, to undertake. Guidelines recommend percutaneous coronary intervention (PCI) if the medical contact-to-balloon time can be kept under 90 minutes, and timely administration of fibrinolytics if greater than 90 minutes. Most US hospitals do not have PCI facilities, which means the decision becomes whether to treat with a fibrinolytic agent, transfer, or both, followed by PCI if needed. Whichever reperfusion approach is used, successful treatment depends on the ED having an integrated and efficient protocol that is followed with haste. Protocols should be regularly reviewed to accommodate changes in clinical practice arising from ongoing clinical trials.

Door-to-balloon delays with percutaneous coronary intervention in ST-elevation myocardial infarction

The benefits of reperfusion in ST-elevation myocardial infarction are time-dependent no matter if epicardial blood flow is restored with primary percutaneous coronary intervention (PCI) or fibrinolysis. Rapid, sustained, and early restoration of flow in the infarct-related artery is necessary to minimize myocardial damage and to improve clinical outcomes. Though fibrinolytic therapy is widely available, it is limited by unpredictable efficacy, reinfarction, and intracranial hemorrhage. PCI has predictable success in opening the artery but is limited by delays in implementation, particularly in transfer patients. The selection of PCI or fibrinolytic therapy for ST-elevation myocardial infarction should be based on knowledge of the benefits and limitations of each strategy. While PCI is the superior strategy if employed rapidly by competent personnel, fibrinolytic therapy should be considered when significant delays to implementation of PCI are anticipated. Continued efforts, aimed at reducing the time to therapy with PCI and fibrinolysis, are of paramount importance.

Impact of treatment delays on outcomes of primary percutaneous coronary intervention for acute myocardial infarction: analysis from the CADILLAC trial

BACKGROUND

The impact of treatment delays on outcomes after primary percutaneous coronary intervention for acute myocardial infarction is controversial.

METHODS

The CADILLAC trial randomized 2082 patients with acute myocardial infarction to stenting versus percutaneous transluminal coronary angioplasty, each with or without abciximab.

RESULTS

Earlier reperfusion (<3 vs 3-6 vs >6 hours) was associated with lower 1-year mortality (2.6% vs 4.3% vs 4.8%, P = .046 for <3 vs > or = 3 hours), more frequent grade 2 to 3 myocardial blush (55% vs 53% vs 44%, P = .003), more frequent complete ST-segment resolution (64% vs 68% vs 47%, P = .006), and greater improvement in left ventricular function. Early reperfusion (<3 vs 3-6 vs > or = 3 hours) was associated with lower mortality in high-risk patients (3.8% vs 6.9% vs 7.0%, P = .051 for <3 vs > or = 3 hours) but not in low-risk patients (1.4% vs 0.6% vs 1.0%, P = .63). Door-to-balloon times were independently correlated with mortality in patients presenting early after the onset of symptoms (< or = 2 hours, hazard ratio 1.24, P = .013) but not late (>2 hours, heart rate 0.88, P = .33).

CONCLUSIONS

Early reperfusion results in superior clinical outcomes, enhanced microvascular reperfusion, and better recovery of left ventricular function. Incremental treatment delays impact mortality more in high-risk versus low-risk patients and more in patients presenting early versus late after the onset of symptoms. These data emphasize the importance of minimizing treatment delays and have implications regarding patient triage for primary percutaneous coronary intervention.

Role of fibrinolytic therapy in the current era of ST-segment elevation myocardial infarction management

In patients presenting with ST-elevation myocardial infarction, early, effective reperfusion of the culprit artery is needed to salvage myocardium, maintain left ventricular function, and reduce mortality. According to American College of Cardiology/American Heart Association guidelines for the treatment of these patients, the time from medical contact (i.e., firm ST-elevation myocardial infarction diagnosis) to initiation of fibrinolytic therapy (door-to-needle time) should be 30 minutes, and the time from medical contact to percutaneous coronary intervention (PCI) (door-to-balloon time) should be 90 minutes. Because many patients present to hospitals that are not equipped to administer PCI, door-to-balloon time often falls far short of the ideal. When PCI is not readily available, efficient prehospital treatment with t-PA-based fibrinolytic agent formulations that can be delivered in a bolus and do not require weight-based adjustment may reduce mortality rates and result in outcomes similar to PCI when administered promptly.