Influence of early prehospital thrombolysis on mortality and event-free survival (the Myocardial Infarction Triage and Intervention [MITI] Randomized Trial). MITI Project Investigators

STEMI time delays: a clinical perspective : Editorial comment on the article by Verweij et al

STEMI time delays have been introduced as a performance indicator or marker of quality of care. As they are only one part of a very complex medical process, one should be aware of concomitant issues that may be overlooked or even be more important with regard to clinical outcome of STEMI patients. In this overview we try to summarise the most important ones.

Misdiagnosis of ruptured abdominal aortic aneurysm: systematic review and meta-analysis

PURPOSE

To quantitatively summarize the incidence of misdiagnosis of ruptured abdominal aortic aneurysms (rAAA), the most common presenting features, and the commonest incorrect differential diagnoses.

METHODS

A systematic search according to PRISMA guidelines was performed using EMBASE and MEDLINE databases to identify studies reporting the initial rate of misdiagnosis of patients with rAAA. Random-effects meta-analyses were performed to estimate the rate of misdiagnosis, presenting features, and commonest differential diagnoses. A sensitivity analysis was performed for studies reporting after 1990.

RESULTS

Nine studies comprising 1109 patients contributed to the pooled analysis, which found a 42% incidence of rAAA misdiagnosis (95% CI 29% to 55%). In studies reporting after 1990, misdiagnosis was seen in 32% (95% CI 16% to 49%). The most common erroneous differential diagnoses were ureteric colic and myocardial infarction. Abdominal pain, shock, and a pulsatile mass were presenting features in 61% (49%-72%), 46% (32%-61%), and 45% (29%-62%) of rAAAs, respectively.

CONCLUSION

The rate of misdiagnosis of rAAA has remained consistent over time and is concerning. There is a need for an effective clinical decision tool to enable accurate diagnosis and triage at the scene of the emergency.

Pre-hospital versus in-hospital thrombolysis for ST-elevation myocardial infarction

BACKGROUND

Early thrombolysis for individuals experiencing a myocardial infarction is associated with better mortality and morbidity outcomes. While traditionally thrombolysis is given in hospital, pre-hospital thrombolysis is proposed as an effective intervention to save time and reduce mortality and morbidity in individuals with ST-elevation myocardial infarction (STEMI). Despite some evidence that pre-hospital thrombolysis may be delivered safely, there is a paucity of controlled trial data to indicate whether the timing of delivery can be effective in reducing key clinical outcomes.

OBJECTIVES

To assess the morbidity and mortality of pre-hospital versus in-hospital thrombolysis for STEMI.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OVID), EMBASE (OVID), two citation indexes on Web of Science (Thomson Reuters) and Cumulative Index to Nursing and Allied Health Literature (CINAHL) for randomised controlled trials and grey literature published up to June 2014. We also searched the reference lists of articles identified, clinical trial registries and unpublished thesis sources. We did not contact pharmaceutical companies for any relevant published or unpublished articles. We applied no language, date or publication restrictions. The Cochrane Heart Group conducted the primary electronic search.

SELECTION CRITERIA

We included randomised controlled trials of pre-hospital versus in-hospital thrombolysis in adults with ST-elevation myocardial infarction diagnosed by a healthcare provider.

DATA COLLECTION AND ANALYSIS

Two authors independently screened eligible studies for inclusion and carried out data extraction and 'Risk of bias' assessments, resolving any disagreement by consulting a third author. We contacted authors of potentially suitable studies if we required missing or additional information. We collected efficacy and adverse effect data from the trials.

MAIN RESULTS

We included three trials involving 538 participants. We found low quality of evidence indicating uncertainty whether pre-hopsital thrombolysis reduces all-cause mortality in individuals with STEMI compared to in-hospital thrombolysis (risk ratio 0.73, 95% confidence interval 0.37 to 1.41). We found high-quality evidence (two trials, 438 participants) that pre-hospital thrombolysis reduced the time to receipt of thrombolytic treatment compared with in-hospital thrombolysis. For adverse events, we found moderate-quality evidence that the occurrence of bleeding events was similar between participants receiving in-hospital or pre-hospital thrombolysis (two trials, 438 participants), and low-quality evidence that the occurrence of ventricular fibrillation (two trials, 178 participants), stroke (one trial, 78 participants) and allergic reactions (one trial, 100 participants) was also similar between participants receiving in-hospital or pre-hospital thrombolysis. We considered the included studies to have an overall unclear/high risk of bias.

AUTHORS' CONCLUSIONS

Pre-hospital thrombolysis reduces time to treatment, based on studies conducted in higher income countries. In settings where it can be safely and correctly administered by trained staff, pre-hospital thrombolysis may be an appropriate intervention. Pre-hospital thrombolysis has the potential to reduce the burden of STEMI in lower- and middle-income countries, especially in individuals who have limited access to in-hospital thrombolysis or percutaneous coronary interventions. We found no randomised controlled trials evaluating the efficacy of pre-hospital thrombolysis for STEMI in lower- and middle-income countries. Large high-quality multicentre randomised controlled trials implemented in resource-constrained countries will provide additional evidence for the efficacy and safety of this intervention. Local policy makers should consider their local health infrastructure and population distribution needs. These considerations should be taken into account when developing clinical guidelines for pre-hospital thrombolysis.

Fibrinolysis or primary PCI in ST-segment elevation myocardial infarction

BACKGROUND

It is not known whether prehospital fibrinolysis, coupled with timely coronary angiography, provides a clinical outcome similar to that with primary percutaneous coronary intervention (PCI) early after acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Among 1892 patients with STEMI who presented within 3 hours after symptom onset and who were unable to undergo primary PCI within 1 hour, patients were randomly assigned to undergo either primary PCI or fibrinolytic therapy with bolus tenecteplase (amended to half dose in patients ≥75 years of age), clopidogrel, and enoxaparin before transport to a PCI-capable hospital. Emergency coronary angiography was performed if fibrinolysis failed; otherwise, angiography was performed 6 to 24 hours after randomization. The primary end point was a composite of death, shock, congestive heart failure, or reinfarction up to 30 days.

RESULTS

The primary end point occurred in 116 of 939 patients (12.4%) in the fibrinolysis group and in 135 of 943 patients (14.3%) in the primary PCI group (relative risk in the fibrinolysis group, 0.86; 95% confidence interval, 0.68 to 1.09; P=0.21). Emergency angiography was required in 36.3% of patients in the fibrinolysis group, whereas the remainder of patients underwent angiography at a median of 17 hours after randomization. More intracranial hemorrhages occurred in the fibrinolysis group than in the primary PCI group (1.0% vs. 0.2%, P=0.04; after protocol amendment, 0.5% vs. 0.3%, P=0.45). The rates of nonintracranial bleeding were similar in the two groups.

CONCLUSIONS

Prehospital fibrinolysis with timely coronary angiography resulted in effective reperfusion in patients with early STEMI who could not undergo primary PCI within 1 hour after the first medical contact. However, fibrinolysis was associated with a slightly increased risk of intracranial bleeding. (Funded by Boehringer Ingelheim; ClinicalTrials.gov number, NCT00623623.).

The cost-effectiveness of thrombolysis administered by paramedics

OBJECTIVE

The objective of this study is to estimate the expected health outcomes, costs and cost-effectiveness of changing from current practice, where thrombolytic therapy is given in hospital, to paramedic practice where thrombolytic therapy is administered by appropriately trained paramedics (pre-hospital) for STEMI patients.

METHODS

A decision-analysis microsimulation model was constructed with a 30-day component and a long-term health state transition component. A brief review of the literature was undertaken to obtain data on time-to-needle to populate the model. The primary health outcome was quality-adjusted life years (QALYs); secondary outcomes included cardiac events, procedures and survival. Costs to the Australian healthcare system for the rest of life were taken as the analytical perspective.

RESULTS

On average, STEMI patients gain 0.13 QALYs at an additional life-time cost of $343. The incremental cost-effectiveness ratios were $3428 per life-year gained and $2601 per QALY gained. These estimates were robust to changes in a range of assumptions and parameter values. The most important factor was the time-to-needle - the greater the difference between current practice times and paramedic practice times, the greater the health benefits and lower the cost per QALY (and life-year) gained. A key factor in the model was the substantially lower incidence of heart failure from earlier time-to-needle. Importantly, there was little change in the cost per QALY gained for a wide range of ages; thus, there is no argument to limit thrombolysis by paramedics to above or below an age threshold.

CONCLUSIONS

Paramedics administering thrombolysis can avert some STEMI deaths and the pre-hospital administration of thrombolysis is good value for money.

[Percutaneous transluminal coronary angioplasty in the right ventricle myocardial infarction treatment]

BACKGROUND/AIM

To present the results of percutaneous transluminal coronary angioplasty (PTCA) in the treatment of the patients with acute right ventricle myocardial infarction (ARVMI), with adjuvant analyses of the obtained results in the period of five years (2000-2004).

METHODS

Thrombolytic therapy and the primary percutaneous transluminal coronary angioplasty (PPTCA) was applied within the first 6 hours from the onset of anginous disorders, and rescue PTCA in the period from 6-24 hours from the onset of ARVMI. Results. A total number of 1175 patients, both sexes, 763 (64.8%) males and 412 females (35.2%), mean age 58.4 +/- 7.8 years, were treated for acute myocardial infarction (AIM) of different localization in the period of five years (2000-2004). Anterior infarction was found in 645 (54.8%) of the patients, and inferoposterior infarction (IPI) was localized in 530 patients (45.2%) patients of which in 134 (25.2%) AIMDK was proven. Out of 134 patients with proven acute myocardial of the right ventricle AIMDK, 53 (39.5%) got thrombolytic therapy, 64 patients (47.7%) were treated with the conservative heparin therapy, whereas in 17 patients (12.8%), primary percutaneous coronary angioplasty (PPTCA) was done. Delayed or rescue PTCA was done in 22 (18.8%) patients, in 8 (36.3%) from the group which got thrombolytic therapy, and in 14 (63.7%) treated with the heparin therapy. Out of the total number of 22 patients who got heparin or thrombolytic therapy combined with rescue PTCA, in 7 patients (31.8%) the complete clinical and angiographic effect of thrombolysis with AIM was achieved only by using a balloon. Baloon dilatation with the implantantion of intracoronary stent was performed in another 11 patients (50%), while 2 (9.1%) were sent to revascularization of the myocard due to diffusion changes in each of the 3 blood vessels, and 2 patients (9.1%) died. Of the patients, 17 (12.6%) had PPTCA with the implantation of intracoronary stent with the additional direct inhibitor of the platelet membrane glycoproteins IIb/IIIa (abciximab). All the patients treated in this way survived. They had no side effects nor serious complications. Their clinical recovery was satisfactory. In the first three weeks of the intrahospital period in the group of 45 patients (33.5%) with AIMDK, who got only thrombolytic therapy, 7 patients (15.5%) died, whereas in the group of 50 patients (37.3%) treated only with heparin, 13 (26%) died. In the group of 22 patients (18.8%) treated with the combined therapy with rescue PTCA and heparin or thrombolytic therapy, 2 patients (9.1%) died. In the group of 84 patients (62.6%) with AIMDK, who were treated with thrombolytic therapy with primary or rescue PTCA, 9 (10.7%) died. In the AIMDK group of 134 patients, 22 patients (16.4%) died in the period of 1 month of the hospital treatment, whereas in the second group of 396 patients with IPI, but without IDK, 36 (9.1%) died (chi2 = 4.789; p < 0.001). Out of the total number of 1175 patients with AIM in the five-year period of the intrahospital treatment, 145 patients (12.3%) died. In the group of patients with IPI, 58 patients out of 530 (10.9%) died, whereas 87 patients out of 645 (13.4%) with anterior infarction died, (chi2 = 0.567; p < 0.452).

CONCLUSION

The combination of thrombolytic therapy and PTCA shown in the obtained results completely justified this kind of treatment, and offered the patients with AIMDK a greater chance to surve than they had before.

Quality of life of elderly patients after prehospital thrombolytic therapy

We studied the long-term outcome and quality of life of elderly patients after prehospital thrombolysis to treat acute ST-elevation myocardial infarction. Data of 218 patients after prehospital thrombolytic therapy given by two physician staffed Helicopter Emergency Medical Service (HEMS) units were collected prospectively. Physical and mental status was evaluated at 4--6 months after discharge, and 1-year mortality was determined. Patients older than 65 years were compared with those younger than 65 years. There were 112 elderly and 106 younger patients. The elderly patients had more previous coronary events and more medications. Pain to therapy times between the two groups were equal (<65 years: 108+/-93 min (range 27--500 min) versus >65 years: 108+/-70 min (20-357 min)). After 4--6 months, the Barthel Daily Living Index or the Beck Depression Inventory (BDI) (depression, if BDI >/=10) showed no differences between the two groups (<65 years: 99+/-5 (range 65--100) versus >65 years: 98+/-12 (10--100); BDI>/=10, 18% versus 9%). One-year survival was lower among the elderly (79% versus 93%; p=0.001). No differences in the frequency of arrhythmias, haemodynamic problems during thrombolysis or complications such as intracranial haemorrhage after thrombolysis were detected. We concluded that elderly patients treated with prehospital thrombolysis for acute ST-elevation myocardial infarction recover mentally and physically as well as younger patients.

Potential diversion rates associated with prehospital acute myocardial infarction triage strategies

Thisstudy examines the potential number of patients who would be diverted from hospitals without percutaneous coronary intervention (PCI) capability, to centers with this capability, as a result of prehospital triage strategies for patients with suspected acute myocardial infarction (AMI). All patients with AMI admitted during a 1-year study period at two urban hospitals without PCI capability were identified through a prospectively maintained AMI registry. Pertinent clinical data were extracted from the AMI registry and patients' medical records. Patients were considered to have been eligible for prehospital diversion to a PCI center if they had ischemic symptoms of greater than 20 min and less than 24 h duration, and electrocardiographic changes consistent with ST elevation AMI (STEMI) were noted at the time of Emergency Department (ED) arrival or before arrival. There were 176 patients with AMI identified. One hundred three patients were transported to the ED by Emergency Medical Services (EMS). Of these, 39 had a clinical presentation and diagnostic EKG evidence of STEMI on ED arrival. Implementation of a prehospital triage strategy for patients with suspected STEMI may result in the diversion of 22% of patients with AMI from hospitals without PCI capability, assuming perfect specificity of prehospital triage. Actual implementation of a prehospital AMI diversion protocol may have an even greater impact on nonreceiving hospitals.

Efficacy and safety of tenecteplase in combination with the low-molecular-weight heparin enoxaparin or unfractionated heparin in the prehospital setting: the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 PLUS randomized trial in acute myocardial infarction

BACKGROUND

The combination of a single-bolus fibrinolytic and a low-molecular-weight heparin may facilitate prehospital reperfusion and further improve clinical outcome in patients with ST-elevation myocardial infarction.

METHODS AND RESULTS

In the prehospital setting, 1639 patients with ST-elevation myocardial infarction were randomly assigned to treatment with tenecteplase and either (1) intravenous bolus of 30 mg enoxaparin (ENOX) followed by 1 mg/kg subcutaneously BID for a maximum of 7 days or (2) weight-adjusted unfractionated heparin (UFH) for 48 hours. The median treatment delay was 115 minutes after symptom onset (53% within 2 hours). ENOX tended to reduce the composite of 30-day mortality or in-hospital reinfarction, or in-hospital refractory ischemia to 14.2% versus 17.4% for UFH (P=0.080), although there was no difference for this composite end point plus in-hospital intracranial hemorrhage or major bleeding (18.3% versus 20.3%, P=0.30). Correspondingly, there were reductions in in-hospital reinfarction (3.5% versus 5.8%, P=0.028) and refractory ischemia (4.4% versus 6.5%, P=0.067) but increases in total stroke (2.9% versus 1.3%, P=0.026) and intracranial hemorrhage (2.20% versus 0.97%, P=0.047). The increase in intracranial hemorrhage was seen in patients >75 years of age.

CONCLUSIONS

Prehospital fibrinolysis allows 53% of patients to receive reperfusion treatment within 2 hours after symptom onset. The combination of tenecteplase with ENOX reduces early ischemic events, but lower doses of ENOX need to be tested in elderly patients. At present, therefore, tenecteplase and UFH are recommended as the routine pharmacological reperfusion treatment in the prehospital setting.

Acute myocardial infarction

Acute myocardial infarction is a common disease with serious consequences in mortality, morbidity, and cost to the society. Coronary atherosclerosis plays a pivotal part as the underlying substrate in many patients. In addition, a new definition of myocardial infarction has recently been introduced that has major implications from the epidemiological, societal, and patient points of view. The advent of coronary-care units and the results of randomised clinical trials on reperfusion therapy, lytic or percutaneous coronary intervention, and chronic medical treatment with various pharmacological agents have substantially changed the therapeutic approach, decreased in-hospital mortality, and improved the long-term outlook in survivors of the acute phase. New treatments will continue to emerge, but the greatest challenge will be to effectively implement preventive actions in all high-risk individuals and to expand delivery of acute treatment in a timely fashion for all eligible patients.

Feasibility and timing of prehospital administration of reteplase in patients with acute myocardial infarction

BACKGROUND

In myocardial infarction patients undergoing thrombolysis, treatment delays negatively impact outcomes. This pilot study was conducted to determine the feasibility and timing of field administration of intravenous double bolus reteplase in patients with ST-elevation myocardial infarction.

METHODS

Sixty three patients with symptoms and EKG changes consistent with acute myocardial infarction of less than six hours duration received the first bolus of reteplase before arriving at the emergency department. A second bolus of reteplase was given in the emergency department. Subsequent resolution of ST-segment elevation was measured. Mean time from symptom onset to paramedic dispatch, and paramedic arrivals to first bolus of reteplase were measured. The mean time from the first bolus of reteplase to heparin bolus in an emergency department was also measured. All patients with evidence of ST-elevation and suspected acute myocardial infarction gave consent for the thrombolytic therapy. There were no refusals of therapy among those candidates eligible for thrombolysis.

RESULTS

The mean times from the first bolus of reteplase to heparin bolus in the emergency department was substantially longer than the in-field times. Resolution of ST-segment elevation was recorded in 52 of the 63 patients and the times of resolution ranged from five minutes after the first bolus dose to 190 minutes after the second bolus of reteplase. Resolution of ST-segment elevation and relief of pain occurred almost simultaneously.

CONCLUSIONS

These results demonstrated that in-field administration of thrombolytic therapy is a viable option to reduce the delay from symptom onset to initiation of thrombolysis. They demonstrated that satisfactory resolution of ST-segment elevation can be recorded in the field. The reduction in mortality observed in this study is comparable to previously published studies on inpatients.

Acute ischemic syndromes. Early response

The optimal treatment of patients with AIS depends on a well-run, integrated system of care involving patients and teams of health care professionals. It begins with patient education and extends to a method for accessing an efficient and effective EMS system. Medics must be well equipped and well trained to evaluate and begin initial treatment during prompt transport to an appropriate hospital. The role of out-of-hospital 12-lead ECGs and thrombolysis is reviewed and may be appropriate for some EMS systems. The initial evaluation and treatment in the ED goes on simultaneously and is a dynamic process. Prompt treatment with oxygen, nitroglycerin, morphine, and aspirin is indicated. Initial risk stratification is based on the first ECG, cardiac biomarkers, and the clinical history and physical exam. Disposition and further evaluation is individualized according to the initial work-up and risk assessment.

Prehospital thrombolysis in acute myocardial infarction

Efficacy of reperfusion therapy in acute myocardial infarction (AMI) is strictly time-dependent. Most benefit is achieved with initiation of therapy within the first 60-90 min after onset of symptoms. The majority of patients with AMIs are seen within this time window by emergency medical services. Moreover, average time gain of about 60 min is possible by prehospital thrombolysis. Randomized studies yielded a better outcome when a time gain of 90 min and more was achieved. Prehospital diagnosis of AMI is reliable. Moreover, out-of-hospital thrombolysis has no additional specific risks nor is it an obstacle for later percutaneous intervention. Consequently, patients seen within the first 60-90 min after onset of symptoms or for whom a time gain of 90 min or more can be expected should receive immediate prehospital thrombolysis.

Critical decision making in the management of patients with acute myocardial infarction and other acute coronary syndromes

The decision-making process for emergency physicians in managing patients with signs or symptoms of AMI or unstable angina is quite different than that used by other specialists who might evaluate such patients in a less critical setting (e.g., a cardiologist seeing a private patient in an office or outpatient clinic environment). The emergency physician's evaluation must be highly focused and follow established principles of emergency medicine (Fig. 2). Although the evaluation and treatment of all patients must be individualized to some degree, increasing experience at high-volume centers nationally indicates that well-constructed institutional strategies, protocols, and critical pathways can help emergency physicians to provide consistent, cost-effective management of such patients.

Accuracy and clinical effect of out-of-hospital electrocardiography in the diagnosis of acute cardiac ischemia: a meta-analysis

STUDY OBJECTIVE

We sought to evaluate quantitatively the evidence on the diagnostic performance of out-of-hospital ECG for the diagnosis of acute cardiac ischemia (ACI) and acute myocardial infarction (AMI) and the clinical effect of out-of-hospital thrombolysis.

METHODS

We conducted a systematic review and meta-analysis of the English-language literature published between 1966 and December 1998 on the diagnostic accuracy of out-of-hospital ECG and the clinical effect of out-of-hospital thrombolysis. Both prospective and retrospective studies qualified for the assessment of diagnostic performance. For clinical effect, data from prospective nonrandomized studies were synthesized separately from data from randomized trials. Diagnostic performance was assessed by using estimates of test sensitivity, specificity, and diagnostic odds ratios and was summarized by using summary receiver-operating characteristic curves. Measures of clinical effect included time savings, early ventricular function, early mortality, and long-term survival.

RESULTS

Diagnostic accuracy was evaluated in 11 studies with a total of 7,508 patients. Data were available for ACI in 5 studies and for AMI in 8 studies. For ACI, the random-effects pooled sensitivity was 76% (95% CI, 54% to 89%), the specificity was 88% (95% CI, 67% to 96%), and the diagnostic odds ratio was 23 (95% CI, 6.3 to 85). The respective figures for AMI were sensitivity of 68% (95% CI, 59% to 76%), specificity of 97% (95% CI, 89% to 92%), and diagnostic odds ratio of 104 (95% CI, 48 to 224). Both in nonrandomized (n=4, total 1,531 patients) and randomized (n=9, total 6,643 patients) studies, out-of-hospital thrombolysis shortened the time from onset of symptoms to thrombolytic treatment by 40 to 60 minutes. Data on short-term ejection fraction were sparse. Hospital mortality was reduced by 16% (95% CI, 2% to 27%) among randomized trials, and a similar estimate of effect was seen in nonrandomized studies. There was no clear effect on long-term mortality, but data were sparse.

CONCLUSION

Out-of-hospital ECG has excellent diagnostic performance for AMI and very good performance for ACI. Out-of-hospital thrombolysis achieves time savings and improves short-term mortality, but the effect on long-term mortality is unknown.

ACUTE MYOCARDIAL INFARCTION IN THE PREHOSPITAL SETTING

Despite research and public education, myocardial disease, infarction, and death from cardiac arrest continue to be one of the top public health issues. Many patients experiencing AMIs access health care and receive initial treatment from EMS personnel in the prehospital setting. Prompt identification and diagnosis of these patients, relief of chest pain, and shortening delays to definitive care can decrease morbidity and mortality. Prehospital diagnosis of AMI is enhanced with the use of 12-lead electrocardiograms, which can shorten time to thrombolysis or angiography. Prehospital use of thrombolytic agents has not gained widespread use in this country; it is, however, commonplace in Europe, where research suggests improved outcomes when thrombolysis is initiated prior to hospital arrival. Resuscitation of out-of-hospital cardiac arrest patients is difficult, resulting in dismal survival rates. Factors that appear to be associated with enhanced survival are witnessed arrest, bystander CPR, and short response times to defibrillation.

A review of the long term effects of thrombolytic agents

Unequivocal evidence exists that reperfusion therapy, when given within 12 hours after onset of symptoms, saves the lives of patients with acute myocardial infarction (MI). As a result, the routine use of such treatment has increased rapidly since the mid-1980s but the rates of utilisation have been relatively static over the last decade at approximately 50% of patients with acute MI. The major question arising in this respect is: is the benefit of reperfusion therapy, which is achieved during the acute phase in evolving MI, maintained on the long term? The main thrombolytic agents currently in use are streptokinase, alteplase, anistreplase, urokinase and reteplase. Other studies compared coronary angioplasty with thrombolytic therapy and investigated the effect of an additional angioplasty procedure after failed thrombolytic therapy. Furthermore, several studies have been performed to investigate the effect of initiation of reperfusion therapy before hospital admission. It is generally agreed that, in particular, patients receiving early treatment within 6 hours from onset of symptoms and patients with ST elevation benefit most from thrombolytic therapy. One would theoretically expect that infarct size reduction achieved by reperfusion therapy would also have a beneficial effect on the survival, not only during the hospital stay but also afterwards, resulting in diverging survival curves between patients who received reperfusion therapy and those who did not. However, the survival curves run perfectly parallel after hospital discharge from 1 year up to year 10 in most studies. The explanation for a lack of extra benefit may be a net result of combining the results of several subgroups. For example, thrombolytic therapy results in more frequent reinfarction especially in the first year, or patients with low left ventricular ejection fraction could survive the hospital phase because of effective thrombolytic therapy, but they survive at high risk. Although several trials suggest that primary percutaneous transluminal coronary angioplasty may be more beneficial than thrombolytic therapy in acute MI, these data should be interpreted cautiously unless confirmed by larger studies with long term results. In addition, evidence exists to suggest that administration of fibrinolytic treatment, under certain conditions, before hospital admission may lead to further improvement of a patient's prognosis. Again, further investigation is warranted. The conclusion is that clear evidence exists that the early improved survival after thrombolytic therapy has been shown to be maintained beyond a decade. However, the expected theorectical additional benefit of reperfusion therapy after hospital discharge has not been observed.

Thrombolysis with saruplase versus streptokinase in acute myocardial infarction: five-year results of the PRIMI trial

BACKGROUND

Short-term safety and efficacy of thrombolysis with saruplase in acute myocardial infarction have been shown in several trials. To assess long-term outcome of patients treated with saruplase or streptokinase for myocardial infarction, a 5-year follow-up of patients included in the Pro-Urokinase in Myocardial Infarction Trial was performed.

METHODS AND RESULTS

Follow-up data are available from 8 centers on 255 (92.4%) of 276 included patients. The 5-year mortality rate was comparable with 20.8% of patients in the saruplase group and 16.9% in the streptokinase group (odds ratio 1.29, 95% confidence interval 0.69 to 2.42). In both groups, a considerable number of fatal cardiovascular events occurred more than 1 year after study inclusion. Rates of percutaneous transluminal coronary angioplasty and coronary artery bypass grafting were comparable in both groups. Reinfarction within 5 years occurred in 19.0% of patients in the saruplase group and tended to be less frequent at 10.8% after streptokinase treatment (odds ratio 1.94, 95% confidence interval 0.98 to 3.84). In both groups, the majority of reinfarctions took place more than 3 months after study inclusion. The 5-year stroke rate was 3.6% and 7.2% in the saruplase and streptokinase groups, respectively (odds ratio 0.49, 95% confidence interval 0.16 to 1.47). Subjective symptoms of heart failure and angina pectoris were comparable in both groups.

CONCLUSIONS

Our data are consistent with a similar long-term outcome for patients treated with saruplase or streptokinase. Despite the low-risk profile of the patient cohort, there were considerable adverse event rates over a 5-year period.

Clinical epidemiology of acute myocardial infarction

In the United States by mid-century, cardiovascular disease accounted for more than half of all deaths. In the second half of this century, 85% of reduction in age-adjusted mortality rates from all causes can be ascribed to the decline in death from cardiovascular disease and stroke. Approximately half of such dramatic decline in mortality rates from ischemic heart disease (IHD) can be explained by primary and secondary prevention and half by therapeutic improvements. Epidemiology of therapeutic regimens in acute myocardial infarction (AMI) indicates substantial increases in the use of thrombolytic therapy, aspirin, beta-blockers and, in some countries, coronary angioplasty. The long-term results of several thrombolytic trials have shown the persistence of early benefit until 10 years after AMI. However, approximately half of the patients with AMI are admitted to the hospital too late to fully benefit from thrombolytic therapy, and one fourth of eligible patients do not receive any form of reperfusion. Primary angioplasty is advocated by some as the treatment of choice in AMI. The present results are not convincing enough to induce the enormously complex and costly reorganization of the health system, allowing the immediate access to coronary angiography for all or most patients with AMI. However, stenting the infarct coronary artery at the site of previous occlusion appears to improve the immediate and medium-term results of coronary revascularization procedures. Approximately half of the AMI survivors are rehospitalized within 1 year after the index event, and postinfarction mortality rate remains exceedingly high. After AMI, prognostic and therapeutic procedures have been introduced in the absence of evidence from controlled trials of their effectiveness profile. Outcome research is needed to standardize effective post-AMI policies. Moreover, new strategies are needed to reduce the incidence and mortality rates of acute ischemic events. A number of new candidate risk factors for IHD are emerging; they are associated with endothelial dysfunction, thrombogenic state, and inflammatory state. It is hoped that advances in molecular approach to cardiovascular disease, molecular genetics and transgenic techniques will allow better understanding and more effective therapeutic strategies to prevent and control IHD.

New thrombolytic strategy: bolus administration of tPA and urokinase-fibrinogen conjugate

Increased efficacy of thrombolytic therapy requires a comprehensive search for new and novel therapeutic strategies. Many new modified forms of plasminogen activators have been obtained by means of chemical and biological synthesis. However, clinical findings demonstrate that the reperfusion level achieved during thrombolysis remains the same for various thrombolytic agents, irrespective of an extensive search for an "ideal" thrombolytic. Thrombolytic therapy may be complicated by treatment delays, cumbersome schemes of preparation and administration, and hemorrhagic and rethrombotic events. These limitations may be overcome, at least in part, by applying combined thrombolysis with plasminogen activators exhibiting complementary actions and different pharmacokinetic profiles. The combined action of native thrombolytics allows the use of lower doses and simplified schemes of administration, yielding encouraging results in experimental models. Long-acting forms of plasminogen activators are being developed and tested in combination with tissue-type plasminogen activator as a trigger of thrombolysis. The combination of short- and long-acting plasminogen activators appears promising and potentially eligible for bolus administration to patients. On the basis of our own experimental results and data in the literature, we suggest a new thrombolytic strategy connected with the single injection of a combination of complementary and pharmacokinetically different plasminogen activators.

Pre-hospital thrombolysis

The administration of thrombolytic drugs outside hospital by emergency physicians is becoming more common. However, few in Europe live in areas where such a service is provided. The data suggest that the advantages can be appreciable in some circumstances but that the strategy may not be universally applicable.

Searching for the evidence in pre-hospital care: a review of randomised controlled trials. On behalf of the Ambulance Response Time Sub-Group of the National Ambulance Advisory Committee

OBJECTIVES

To identify randomised controlled trials (RCTs) which evaluate aspects of pre-hospital care; to perform categorisation by theme; to compare the sensitivity and precision of the search databases.

DATA SOURCES

August 1997 updates of MEDLINE and EMBASE databases, using the Datastar online system. Papers published in 1987 or later were included, with no language restrictions.

STUDY SELECTION

A trial was eligible for inclusion if it was judged, by two independent and blinded assessors, that participants followed up in the trial were definitely or possibly assigned prospectively to one of two or more alternative forms of healthcare with random allocation or a quasi-random method of allocation.

RESULTS

The literature search retrieved 849 papers, of which 569 (67%) were in MEDLINE and 486 (57%) in EMBASE. Forty one (5%) were confirmed as reports of RCTs or quasi-RCTs, and the total number of individual trials was 38. Ten of these trials dealt with thrombolytic drugs; 14 were concerned with other drugs, 12 with equipment, and two with other interventions. Four trials were based on a sample size of more than 1000, and seven reported a statistically significant effect on mortality. All 41 papers were in EMBASE, and all but one were also in MEDLINE.

CONCLUSIONS

Evidence based policy making with respect to the organisation of pre-hospital services cannot depend on RCTs. In the current relative absence of such evidence, practitioners and decision makers must use alternative information sources. A future review could examine a broader range of literature and be based on a wider search of published and unpublished material.

New strategy of thrombolysis. Conjunctive effect of plasminogen activators with different pharmacokinetic profile

Combined actions of native and prolonged thrombolytics allow the use of lower doses and simplified schemes of administration, thus yielding significant results in experimental therapy regarding the efficacy and safety of thrombolysis. Development of prolonged forms of plasminogen activators and testing their effect in combination with the thrombolysis trigger are well founded and of current interest. Thrombolytic compositions on the basis of short- and long-term-acting plasminogen activators appear to be promising and potentially eligible for bolus administration.

Thrombolysis in acute myocardial infarction improves prognosis and prolongs life but will increase the prevalence of heart failure in the geriatric population

This paper will review the hypothesis that early complete thrombolytic therapy in acute myocardial infarction reduces mortality and improves prognosis. ACE inhibitors improve remodelling and anti-platelet drugs or interventional procedures prevent reocclusion of the infarct related coronary artery. Most patients are left with significant myocardial damage and this effect is cumulative with subsequent infarction. The average age of death has increased by 10 years in the last three decades, so that many older patients survive. They have survived acute myocardial infarction and we now have a significant population with important heart failure despite good thrombolytic therapy.

Prehospital-initiated thrombolysis

OBJECTIVE

To evaluate the feasibility, safety, and efficacy of prehospital-initiated thrombolysis in decreasing the mortality rate due to acute myocardial infarction.

DATA SOURCES

English-language clinical studies, abstracts, and review articles identified from MEDLINE searches and bibliographies of identified articles. Epidemiologic data were extracted from the Internet.

STUDY SELECTION

Eight randomized clinical trials and two meta-analyses that compared prehospital-initiated thrombolysis with in-hospital-initiated thrombolysis.

DATA EXTRACTION

Pertinent studies were selected and the data were synthesized into a review format.

DATA SYNTHESIS

Early reperfusion of an infarct-related coronary artery is associated with lower mortality rates. Most of the delay in initiating treatment is caused by patient delay rather than transport delay or hospital delay. In addition, more than 30% of eligible patients do not receive thrombolytic therapy. Prehospital initiation of thrombolysis has been evaluated as a means of decreasing hospital delay and increasing the number of eligible patients receiving thrombolysis. Clinical trials document that prehospital-initiated thrombolysis is feasible and safe, and saves time. Of the eight randomized trials, three demonstrated a decrease in either cardiac or total mortality with prehospital thrombolysis. All studies were limited by relatively small sample sizes. Two published meta-analyses suggest a 16-17% reduction in mortality with prehospital thrombolysis. In the US, prehospital thrombolysis is not routinely recommended due to medical issues related to diagnostic accuracy and monitoring, legal concerns, and economic implications. Additional strategies, such as community-wide education and prehospital diagnostic electrocardiograms (ECGs), are being studied.

CONCLUSIONS

In clinical trials, prehospital-initiated thrombolytic therapy was shown to be safe and probably more effective than in-hospital administration of thrombolytic therapy, but this has not proven feasible in the US at this time. Despite time-savings by decreasing treatment delay with prehospital-initiated thrombolysis, patient delay still persists and accounts for the majority of delay. Future investigations will center on increasing the number of patients treated with thrombolytic agents through patient education, in-patient and out-patient programs that rapidly identify eligible patients, as well as prehospital diagnostic ECGs.

Factors associated with rehospitalization in patients with acute myocardial infarction

Rehospitalization of patients surviving acute myocardial infarction is common, but why it occurs is not well documented. In Seattle area hospitals, rehospitalization was frequent, particularly for women and those with extensive cardiac histories.