Quantification of the benefit of earlier thrombolytic therapy: five-year results of the Grampian Region Early Anistreplase Trial (GREAT)

Acute Coronary Syndrome

Acute coronary syndromes encompass a heterogenous group of patients with different clinical presentations, who have differences in both the extent and severity of underlying coronary atherosclerosis and who have different degrees of risk of progression to myocardial infarction. For each patient, the pre-hospital practitioner should make individual treatment decisions based on the history and examination, the ECG findings, the facilities and diagnostic equipment available and the transfer time to the nearest appropriate hospital. Patients with acute ischaemic chest pain should have oxygen, aspirin, nitrates and opioid analgesia. A 12 lead ECG should be performed within 5 minutes of initial assessment. If the ECG reveals ST-segment elevation or presumed new LBBB, this signifies acute myocardial infarction and in most cases immediate reperfusion therapy should be considered. The evidence of benefit in terms of mortality and morbidity following prompt anti-platelet and fibrinolytic therapy in such cases is unequivable. Pre-hospital fibrinolysis is now well established and should be undertaken in patients with acute infarction on clinical and ECG grounds if the transfer to hospital is likely to exceed 30 minutes and it is less than 12 hours since the onset of pain. Patients with no ECG evidence of infarction may still be at considerable risk and should still be conveyed to the nearest appropriate medical facility. Whilst en-route, they should receive aspirin, nitrates, low molecular weight heparin (LMWH) and beta blockers provided there are no contra-indications.

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.

Prospective observational cohort study of time saved by prehospital thrombolysis for ST elevation myocardial infarction delivered by paramedics

OBJECTIVES

To evaluate a system of prehospital thrombolysis, delivered by paramedics, in meeting the national service framework's targets for the management of acute myocardial infarction.

DESIGN

Prospective observational cohort study comparing patients with suspected acute myocardial infarction considered for thrombolysis in the prehospital environment with patients treated in hospital.

SETTING

The catchment area of a large teaching hospital, including urban and rural areas.

PARTICIPANTS

201 patients presenting concurrently over a 12 month period who had changes to the electrocardiogram that were diagnostic of acute myocardial infarction or who received thrombolysis for suspected acute myocardial infarction.

MAIN OUTCOME MEASURES

Time from first medical contact to initiation of thrombolysis (call to needle time), number of patients given thrombolysis appropriately, and all cause mortality in hospital.

RESULTS

The median call to needle time for patients treated before arriving in hospital (n=28) was 52 (95% confidence interval 41 to 62) minutes. Patients from similar rural areas who were treated in hospital (n=43) had a median time of 125 (104 to 140) minutes. This represents a median time saved of 73 minutes (P < 0.001). Sixty minutes after medical contact 64% of patients (18/28) treated before arrival in hospital had received thrombolysis; this compares with 4% of patients (2/43) in a cohort from similar areas. Median call to needle time for patients from urban areas (n=107) was 80 (78 to 93) minutes. Myocardial infarction was confirmed in 89% of patients (25/28) who had received prehospital thrombolysis; this compares with 92% (138/150) in the two groups of patients receiving thrombolysis in hospital.

CONCLUSIONS

Thrombolysis delivered by paramedics with support from the base hospital can meet the national targets for early thrombolysis. The system has been shown to work well and can be introduced without delay.

Emergency calls not requiring an urgent ambulance response: expert consensus

OBJECTIVES

This study sought expert consensus about which categories of patients from 248 Medical Priority (MPDS) ambulance dispatch codes might be appropriate for a nonemergency response or for whom dispatch of an ambulance might be appropriately denied if the patient were referred to a more suitable health care provider.

METHODS

A Delphi technique was used. Ten physicians, from the specialities of emergency medicine, general practice, and pre-hospital care formed the expert panel but were blinded to each other's identity. Participants received a written description of the operation of the MPDS and the Delphi technique and voted independently by mail.

RESULTS

Using majority voting, 54 dispatch codes (22%) were recommended for a nonemergency response/referral. This equates to 12.44% of annual emergency calls in a typical UK ambulance service (n = 9,021; 95% confidence interval, 12.21 to 12.69%). The kappa statistic (chance-corrected proportional agreement) between members of the expert panel was 0.62 (substantial).

CONCLUSIONS

The recommended dispatch codes for non-emergency response or referral represent a significant proportion of emergency ambulance calls. Theoretically, the implementation of nonemergency responses could have the benefit of reducing accidents involving emergency ambulances and could lead to improved response times for critically ill patients by freeing up resources. It could also support the targeting of patients to appropriate health care providers on first contact with the health service. However, given the poor reliability of expert opinion, further research using clinical outcome data is required to validate the recommendations made in this article before changing existing ambulance response systems.

Effect of socioeconomic status on out-of-hospital transport delays of patients with chest pain

STUDY OBJECTIVES

The effect of socioeconomic status on out-of-hospital care has not been widely examined. We determine whether socioeconomic status was associated with out-of-hospital transport delays for patients with chest pain.

METHODS

A retrospective study of patients with chest pain transported by means of ambulance in Toronto, Ontario, Canada, in 1999 was conducted. The primary outcome measure was the 90th percentile system response interval, with secondary outcomes being the 90th percentile on-scene interval, transport interval, and total out-of-hospital interval. Socioeconomic status was the primary independent variable. Covariates were age, sex, case severity, dispatch and return priority, time and day of transport, paramedic training, and percentage of high-rise apartments in the region.

RESULTS

Four thousand three hundred fifty-six patients met the inclusion criteria. The 90th percentile system response interval and total out-of-hospital interval were 11 minutes and 49 minutes, respectively. In multivariate analyses, the highest socioeconomic status neighborhoods were significantly associated with decreased system response interval (34.0 seconds; 95% confidence interval [CI] 6.2 to 70.9 seconds) and transport interval (132.3 seconds; 95% CI 24.1 to 229.6 seconds). In addition, age (+45.3 seconds per 10 years; 95% CI 13.3 to 75.1 seconds), female sex (+205.0 seconds; 95% CI 78.1 to 287.7 seconds), and advanced care paramedic crews (+371.6 seconds; 95% CI 263.3 to 490.1 seconds) were associated with delays in total out-of-hospital interval. Lastly, calls originating from the highest socioeconomic status neighborhoods were dispatched the highest proportion of advanced care paramedic crews, despite similar dispatch priorities and case severities.

CONCLUSION

High socioeconomic status neighborhoods were associated with shorter out-of-hospital transport intervals for patients with chest pain. In addition, out-of-hospital delays were associated with age, sex, and advanced care paramedic crew type, with calls from the highest socioeconomic status neighborhoods being most likely to receive advanced care paramedic crews.

Identification of acutely ischemic myocardium using ultrasonic strain measurements. A clinical study in patients undergoing coronary angioplasty

OBJECTIVES

The goal of this study was to investigate whether the changes in myocardial deformation measured with ultrasonic strain could accurately identify acutely ischemic myocardium during coronary angioplasty.

BACKGROUND

Early identification of acute myocardial ischemia has important clinical implications. The accuracy of ultrasonic strain for the detection of acute myocardial ischemia has been validated in animal experiments but has not been investigated in the clinical setting.

METHODS

In 73 patients (64 +/- 12 years), either radial or longitudinal strain values were monitored in the "at-risk" segments before, during, and early after right, circumflex, and left anterior descending coronary angioplasty. Based on the visual wall motion assessed before the angioplasty, segments were divided into normokinetic (group I) and hypo/akinetic (group II). Strain data in the "at-risk " segments were compared with values derived from the adjacent nonischemic segments and normal values in 20 controls.

RESULTS

Coronary occlusion induced a marked reduction in the systolic strain both in the radial (from 49 +/- 6.9% to 23 +/- 4.6% in group I and from 21.9 +/- 11% to 11.3 +/- 8.4% in group II, p < 0.001) and longitudinal directions. Concomitantly, postsystolic strain increased (from 3.8 +/- 3.1% to 14.6 +/- 9.5% in group I, and from 4.4 +/- 3.7% to 11.3 +/- 7.8% in group II in radial direction, p < 0.001). Upon reperfusion, all deformation parameters returned to near preocclusion values. In comparison with control, baseline, and reperfusion data, the systolic and postsystolic strain parameters measured during total coronary occlusion identified acutely ischemic myocardium with a sensitivity of 86% to 95% and a specificity of 83% to 89%.

CONCLUSIONS

In this model of acute ischemia, ultrasonic strain indexes differentiate acutely ischemic segments from both normal and dysfunctional myocardium. This should be a promising new approach to the bedside monitoring of acute ischemic changes in regional myocardial function.

Implementing paramedic thrombolysis--an overview

The UK Government has made improvements in cardiac care a high priority. The publication in 2000 of the National Service Framework for Coronary Heart Disease and the NHS Plan set out national standards for the management of suspected heart attack, including challenging targets for reducing treatment delays for administration of thrombolytic therapy. This paper discusses the background, evidence base and challenges of implementing one component of the Government's drive to improve cardiac care: the NHS Plan commitment to a three year programme to equip and train ambulance paramedics to safely provide thrombolysis for appropriate patients.

[Acute myocardial infarction management in a hospital center with emergency ambulance service and intensive care unit, without cardiac catheterization laboratory]

OBJECTIVES

We report our experience about acute myocardial infarction management in a small hospital with no possibility of coronarography.

MATERIALS AND METHODS

In 1998, 60 patients were hospitalized for acute myocardial infarction < 10 days. We studied characteristics of patients, the management of myocardial infarction, the mortality.

RESULTS

Our population consisted of 83% of men and 17% of women with a mean age of 63.5 and 74 years respectively. An out-hospital doctor was first warned by 60% of patients. For hospitalization, the emergency ambulance service (SMUR) was used in 45% of cases, out-hospital doctors using these means of transport in 36% of cases. The global time of intervention was 18h30. The mean time for patients managed in the first sixth hours was 2h10. A thrombolysis was applied for 35% of patients (15% in prehospital that is to say 32% of "SMUR patients", and 20% in hospital). A transfer to the neighbouring university hospital for primary or rescue coronary angioplasty was decide for 41% of patients. A total of 77% of our patients underwent a coronarography. The global mortality at 10 days was 13.3% (< 75 years: 10.6%; > 75 years: 23%).

CONCLUSIONS

A low volume centre and with no possibility of coronarography can manage the acute phase of myocardial infarction with results closed to those of the literature.

[Time intervals in primary angioplasty from onset of symptoms until restoration of blood flow]

INTRODUCTION AND OBJECTIVE

A limitation to the widespread use of primary angioplasty is delayed reperfusion. Most current data are from clinical trials and there is little information about the use of primary angioplasty in clinical practice. The objective of this study was to analyze the duration of each stage leading to primary angioplasty in a hospital where it is the treatment of choice for acute myocardial infarction.

PATIENTS AND METHOD

Prospective observational study of patients admitted to our hospital from April 2000 to August 2001 for acute myocardial infarction with an indication for reperfusion. The time intervals from onset of symptoms until the end of angioplasty were analyzed.

RESULTS

Primary angioplasty was performed in 201 of 218 patients with an indication for reperfusion (92%). Median values (percentiles 25-75) were: Time 1 (onset of symptoms-hospital arrival): 91 (50-150) minutes. Time 2 (hospital arrival-call to interventional team): 20 (10-49) minutes. Time 3: (call to interventional team-team arrival): 15 (0-20) minutes. Time 4: (team arrival patient arrival at the catheterization laboratory): 10 (5-15) minutes. Time 5 (patient arrival-opening of coronary artery): 20 (15-30) minutes. Time 6 (opening of coronary artery-TIMI III flow): 10 (0-25) minutes.

CONCLUSIONS

The most time-consuming stage in primary angioplasty was from the onset of symptoms until patient arrival at the hospital (Time 1). Inside the hospital, the most time-consuming stage was the diagnosis and decision to perform angioplasty (Time 2). The rates of primary angioplasty could be increased if delays in reperfusion were reduced with respect to those considered acceptable in current practice guidelines.

Prehospital selection of patients for thrombolysis by paramedics

OBJECTIVE

Heart disease is the major cause of death in Wales. Myocardial infarction accounts for most fatalities either acutely or as a result of late heart failure and unheralded sudden cardiac death. Prompt relief of new coronary occlusions by thrombolytic agents has been shown to reduce significantly both early mortality and subsequent morbidity from acute myocardial infarction. The prehospital delivery of these drugs is feasible, and carries no greater risk than administration in hospital. This study tests the hypothesis that paramedics can identify patients with acute myocardial infarction who are suitable for prehospital thrombolysis, and thus reduce the "call to needle" time.

METHOD

Paramedics from rural Wales were trained in the acquisition and recognition of 12 lead ECGs, and also in the modified indications for thrombolytic therapy as defined by the Joint Royal Colleges Ambulance Liaison Committee (JRCALC). Ninety six consecutive patients, with possible myocardial infarction, were included in the study. The paramedics made an independent decision regarding the eligibility of the patients for thrombolysis before hospital admission, noting the time that they could have administered the drug. These decisions were compared with the treatment subsequently received in hospital.

RESULTS

No errors were made by the paramedics in case selection (specificity of 100% (95% CI 95.9% to 100%)). There was a potential reduction in call to needle time of 41.2 minutes (95% CI 25.7 minutes to 56.9 minutes, p=0.001).

CONCLUSIONS

It was concluded that the paramedic selection of patients for the prehospital administration of a thrombolytic is both feasible and safe.

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.

[Beneficial effects of direct call to Emergency Medical Services on time delays and management of patients with acute myocardial infarction. The RICO (obseRvatoire des Infarctus de Côte-d'Or) data]

The influence of direct calls to specialized Emergency Medical Services in case of suspected myocardial infarction has not been extensively studied. The RICO registry is an exhaustive registry implemented in all six institutions participating in primary care of patients with acute myocardial infarction in one French administrative department (Côte-d'Or). From January 2001 to October 2001, 322 patients were admitted for acute myocardial infarction, among whom only 57 (18%) had directly called emergency medical services after the onset of symptoms. The baseline characteristics of patients who had directly called the emergency services were not different from those of the patients who had not. However, the time from symptom onset to first medical intervention (48 versus 105 minutes, p = 0.02) and from first medical intervention to hospital admission (60 versus 103 minutes, p = 0.02) were markedly shorter in patients who had directly called the emergency medical services. This resulted in a significant increase in the use of reperfusion therapy (70% versus 38%, p = 0.003), including a higher proportion of primary angioplasty (33% versus 20%, p = 0.04). This study documents the beneficial effect of a direct call to the Emergency Medical Services by the patients themselves. Too few patients, however use this opportunity and actions should be taken for informing the lay public of the benefits of this medical service.

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.

Normal flow (TIMI-3) before mechanical reperfusion therapy is an independent determinant of survival in acute myocardial infarction: analysis from the primary angioplasty in myocardial infarction trials

BACKGROUND

Whereas survival after lytic therapy for myocardial infarction is strongly dependent on early administration, it is unknown whether the otherwise excellent outcomes in patients undergoing primary PTCA for acute myocardial infarction, in whom TIMI-3 flow rates of >90% may be achieved, can be further improved by early reperfusion.

METHODS AND RESULTS

Among 2507 patients enrolled in 4 PAMI trials undergoing primary PTCA, spontaneous reperfusion (TIMI-3 flow) was present in 16% at initial angiography. Compared with patients without TIMI-3 flow, those with TIMI-3 flow before PTCA had greater left ventricular ejection fraction (57+/-10% versus 53+/-11%, P=0.003) and were less likely to present in heart failure (7.0% versus 11.6%, P=0.009). Patients with initial TIMI-3 flow had significantly lower in-hospital rates of mortality, new-onset heart failure, and hypotension and had a shorter hospital stay. Cumulative 6-month mortality was 0.5% in patients with initial TIMI-3 flow, 2.8% with TIMI-2 flow, and 4.4% with initial TIMI-0/1 flow (P=0.009). By multivariate analysis, TIMI-3 flow before PTCA was an independent determinant of survival (odds ratio 2.1, P=0.04), even when corrected for by postprocedural TIMI-3 flow.

CONCLUSIONS

Patients undergoing primary PTCA in whom TIMI-3 flow is present before angioplasty present with greater clinical and angiographic evidence of myocardial salvage, are less likely to develop complications related to left ventricular failure, and have improved early and late survival. These data warrant prospective randomized trials of pharmacological strategies to promote early reperfusion before definitive mechanical intervention in acute myocardial infarction.

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.

Optimal prehospital cardiovascular care

Optimal prehospital cardiovascular care may improve the morbidity and mortality associated with acute myocardial infarctions (AMIs) that begin in the community. Reducing the time delays from AMI symptom onset to intervention begins with maximizing effective patient education to reduce patient delay in recognizing symptoms and seeking assistance. Transportation delays can be minimized by appropriate use of 911 systems and improving technological 911 support. Patient triage to heart centers from the prehospital setting requires strict and comprehensive definition of the criteria for these centers by competent, unbiased clinical societies or governmental agencies. Prehospital 12-lead electrocardiograms and initiation of thrombolytic therapy can provide acute diagnosis and early treatment, thus facilitating faster processing and more directed in-hospital intervention. They also minimize over- and undertriage of patients to cardiac centers. Although evidence from investigational trials suggests that many of these procedures are effective, more research is required to ensure correct implementation and quality assurance at all emergency service levels.

Using patient-reportable clinical history factors to predict myocardial infarction

Using a derivation data set of 1253 patients, we built several logistic regression and neural network models to estimate the likelihood of myocardial infarction based upon patient-reportable clinical history factors only. The best performing logistic regression model and neural network model had C-indices of 0.8444 and 0.8503, respectively, when validated on an independent data set of 500 patients. We conclude that both logistic regression and neural network models can be built that successfully predict the probability of myocardial infarction based on patient-reportable history factors alone. These models could have important utility in applications outside of a hospital setting when objective diagnostic test information is not yet be available.

Changes in mortality of acute myocardial infarction as a function of a changing treatment during the last two decades

Forty years ago, after the establishment of coronary care units, a significant decrease in mortality of acute myocardial infarction was noted. Twenty years ago, the break-through of thrombolysis realized once again a significant decrease in mortality. In this study we compare, in a rather small community hospital, the mortality and safety of thrombolytic therapy in acute myocardial infarction with a more conventional, conservative medical therapy. We examined all cases of acute myocardial infarction between 1978 up to 1998 inclusive, concerning treatment and mortality rate after a six month period. To be included in the study, acute myocardial infarction had to fulfill particular inclusion criteria. A total of 1863 cases of acute myocardial infarction were included. The mortality rate of patients with acute myocardial infarction treated with thrombolytic agents was strikingly lower and statistically very significantly different (p < 0.001) in comparison with the mortality rate of patients treated with heparin or coumarine derivatives. The mortality rate dropped from 10.57% in the coumarine group and from 14.95% in the heparin group to 5.41% in the alteplase group, to 4.95% in the anistreplase group and 4.00% in the streptokinase subgroup. The complications directly connected to the treatment did not seem to be different between the five groups, and they were also not more frequent by using thrombolytic agents. In the last 20 years, better preventive measures (life habits, diet, medication) and trials to better control the risk factors have not influenced greatly the average amount of cholesterol in patients with an acute myocardial infarction. Also the percentage of patients with high blood pressure has hardly decreased over the last 20 years. The mortality associated with acute myocardial infarction has decreased significantly with the use of thrombolytics. In most cases, thrombolytics are administered routinely and safely. In this way, they are the first choice therapy for myocardial infarction in smaller hospitals. To obtain excellent coronary patency, thrombolytic agents with a long half-life and with PAI-1 resistance are required in the future. The current measures and medical therapies seem to be insufficient to control the risk factors for coronary atherosclerosis.

Delay times and management of acute myocardial infarction in indigenous and non-indigenous people in the Northern Territory

OBJECTIVES

To investigate differences in presentation and management of Indigenous and non-Indigenous patients hospitalised with acute myocardial infarction (AMI).

DESIGN

Retrospective review of hospital medical records.

PARTICIPANTS AND SETTING

122 patients with definite or possible AMI admitted to hospitals in the Top End of the Northern Territory (NT) in 1996.

MAIN OUTCOME MEASURES

Percentage receiving thrombolytic therapy; delays from symptom onset to primary and emergency department presentations, first and diagnostic electrocardiograms, thrombolytic therapy and aspirin; drugs prescribed during hospitalisation.

RESULTS

Thrombolytic therapy was given to 12/41 Indigenous patients (29%) and 38/81 non-Indigenous patients (47%) (P = 0.06). Presentation delay over 12 hours was the reason for not giving thrombolytic therapy for 14/29 Indigenous patients (48%) and 8/43 non-Indigenous patients (19%) (P < 0.01). Median delay times were longer for Indigenous patients for all six categories of delay, although the difference was significant only for delay to emergency department presentation (10:00 versus 3:26 hours; P < 0.01) and to diagnostic electrocardiogram (8:10 versus 3:50 hours; P < 0.01). Delays were also longer for patients from rural compared with urban areas. Once diagnosed, Indigenous patients were as likely as non-Indigenous patients to receive aspirin (93% versus 96%) and beta-blockers (70% versus 69%) and more likely to receive angiotensin-converting enzyme inhibitors (60% versus 40%; P = 0.03).

CONCLUSIONS

Delays in presentation affect Indigenous people living in rural and urban areas as well as non-Indigenous people living in rural areas. Concerted efforts are needed to improve health service access in rural areas and to encourage Indigenous people with persistent chest pain to present earlier.

Risk of intracranial haemorrhage with bolus versus infusion thrombolytic therapy: a meta-analysis

BACKGROUND

Although thrombolytic therapy given by bolus injection seems to be as effective as infusion over 60-90 min, no single trial has been adequately powered to detect clinically important safety differences between the two strategies. We did a meta-analysis to find out whether bolus administration of thrombolytics is associated with an increased frequency of intracranial haemorrhage.

METHODS

We identified randomised trials comparing bolus with infusion thrombolytic therapy by a search of electronic databases, reference lists, and conference proceedings. Odds ratios for primary intracranial haemorrhage, non-haemorrhagic stroke, mortality, and reinfarction were calculated for each trial and were combined in a fixed-effects model.

FINDINGS

Seven trials, involving a total of 103,972 patients, met our inclusion criteria. Bolus treatment was associated with an increased risk of intracranial haemorrhage compared with infusion (0.8 vs 0.6%; odds ratio 1.25 [95% CI 1.08-1.45]; p=0.003). The increased risk was most striking in trials comparing bolus with infusion administration of the same agent (1.75 [1.32-2.33], p=0.0001), but was also evident in trials comparing a newer-generation bolus agent with standard infusion therapy (1.25 [1.03-1.50]; p=0.02). The rates of non-haemorrhagic stroke (0.94 [0.81-1.09]), 30-day mortality (1.01 [0.97-1.06]), or reinfarction (1.04 [0.97-1.11]) did not differ between the two strategies.

INTERPRETATION

The increased risk of bolus thrombolytic treatment seems to be primarily associated with the method of administration rather than properties of the agents. Although the increased risk of intracranial haemorrhage is small, physicians should balance this risk against the putative benefits of easier administration with no difference in mortality or reinfarction.

Delay in calling for help during myocardial infarction: reasons for the delay and subsequent pattern of accessing care

OBJECTIVE

To determine the reasons for delay in calling for help during acute myocardial infarction and the reasons for choice of first medical contact.

DESIGN

Review of routine medical records and one to one semi-structured interviews.

SETTING

Community survey in city of Glasgow, north of the river Clyde.

PATIENTS

228 men and 85 women aged between 25 and 65 years, respectively, who survived acute myocardial infarction between October 1994 and December 1996.

RESULTS

Only 25% of the subjects made a call for help within one hour of the onset of coronary symptoms; in 40% the delay was greater than four hours. Symptoms were not recognised as coronary in origin in the majority of cases. In all cases where delay was more than one hour the main reasons for the delay were thinking that symptoms would go away or that they were not serious. Requesting the attendance of a general practitioner was the first course of action in the majority of cases (55%); the main reason given was that the patient believed this should always be the first course of action. Reluctance to call the emergency services reflected the belief that the symptoms were not serious enough to warrant an ambulance.

CONCLUSIONS

Strategies to reduce patient delay times in this deprived urban population must focus on educating the public on the recognition and diversity of coronary symptoms and the benefits of presenting promptly to hospital by way of the emergency ambulance service.

Changing the site of delivery of thrombolytic treatment for acute myocardial infarction from the coronary care unit to the emergency department greatly reduces door to needle time

OBJECTIVE

To quantify the change in door to needle time when delivery of thrombolytic treatment of acute myocardial infarction was changed from the coronary care unit to the emergency department.

DESIGN

A comparative observational study using prospectively collected data.

SETTING

Coronary care unit and emergency department of an Australian teaching hospital.

PARTICIPANTS

89 patients receiving thrombolysis in coronary care unit between June 1994 and January 1996, and 100 patients treated in the emergency department between April 1997 and May 1998.

INTERVENTIONS

From April 1997, by agreement between cardiology and emergency medicine, all patients with acute myocardial infarction receiving thrombolysis were treated by emergency physicians in the emergency department.

MAIN OUTCOME MEASURE

Door to needle time measured from time of arrival at the hospital to start of thrombolysis. Other outcomes included pain to needle time and mortality.

RESULTS

Median door to needle times were less for patients treated in the emergency department than in the coronary care unit (37 minutes, 95% confidence interval (CI) 33 to 44 v 80 minutes, 95% CI 70 to 89, respectively; p < 0.0001). Door to needle time was under 60 minutes in 83% of emergency department patients and 26% of coronary care unit patients (57% difference, 95% CI 45% to 69%; p < 0.0001). Median pain to needle time was less for emergency department patients than for coronary care unit patients (161 minutes, 95% CI 142 to 177 v 195 minutes, 95% CI 180 to 209; p = 0.004); times of less than 90 minutes occurred in 18% of emergency department patients v 1% of coronary care unit patients (17% difference, 95% CI 9% to 25%; p < 0.05). Overall mortality was similar in patients treated in the emergency department and the coronary care unit.

CONCLUSIONS

With a collaborative interdepartmental approach, thrombolytic treatment of acute myocardial infarction was more rapid in the emergency department, without compromising patient safety. This should improve the outcome in patients with infarcts treated with thrombolytic agents.

Factors associated with delay in reperfusion therapy in elderly patients with acute myocardial infarction: analysis of the cooperative cardiovascular project

BACKGROUND

Many elderly patients with an acute myocardial infarction (AMI) do not receive thrombolysis within 30 minutes of hospital arrival as recommended by the American College of Cardiology/American Heart Association Guidelines. We sought to identify factors associated with delay in administration of thrombolysis after arrival to the hospital in these patients and to determine whether this delay is associated with increased mortality rates.

METHODS AND RESULTS

By using the Cooperative Cardiovascular Project database, we identified patients who received thrombolysis for an AMI. The patients were stratified into groups by time to thrombolysis after hospital arrival. Among a cohort of 17,379 patients, 22.2% received thrombolysis in the first 30 minutes after hospital arrival. Patients treated after the first 30 minutes were more likely to be older, be female, be diabetic, have a history of hypertension or heart failure, and have less marked ST elevation. They were also more likely to be admitted to smaller hospitals with a lower volume of AMIs and to hospitals without a cardiac catheterization laboratory. The 30-day mortality rate was significantly lower for patients treated within the first 30 minutes. After adjustments were made for clinical and hospital characteristics, delays in therapy beyond 30 and 90 minutes were associated with an increase in 1-year mortality rates of 9% and 27%, respectively, compared with delays for patients treated within 30 minutes.

CONCLUSIONS

After hospital arrival, time to treatment with thrombolytic therapy is longer than recommended in a significant proportion of patients. Clinical characteristics and institutional factors are associated with the delay in treatment. The more rapid treatment of appropriate elderly patients with an AMI probably will reduce mortality rates.

Reduction of congestive heart failure symptoms by very early fibrinolytic therapy in acute myocardial infarction: a long-term follow-up

BACKGROUND

In patients with acute myocardial infarction (MI), early fibrinolytic therapy results in improved survival and preservation of ventricular function. The purpose of the study was to determine whether very early treatment also reduces the development of congestive heart failure.

METHODS AND RESULTS

During the years 1984 to 1989, 358 consecutive patients with acute MI were treated with streptokinase, 161 within the first 1.5 hours from the onset of chest pain (group A) and 197 within 1.5 to 4.0 hours (group B). In 68, fibrinolysis was initiated in the prehospital setting pioneered by our group. Symptoms related to heart failure including dyspnea on exertion, fatigue, orthopnea, paroxysmal nocturnal dyspnea, nocturia, and peripheral edema, in addition to pulmonary edema events, were assessed during 5 years of follow-up. The evaluation was based on medical records and a detailed questionnaire, which was filled in by the investigators. A favorable significant effect of very early thrombolysis on the development of most of these limiting symptoms appeared 3 months after hospital discharge and persisted thereafter (P <.05). During hospitalization, pulmonary edema attacks occurred less frequently in patients from group A (23% vs 36.5%, P <.01). This difference persisted during 4 years of follow-up (13% vs 36%, P <.001).

CONCLUSIONS

Our data demonstrate that very early fibrinolytic therapy results in a significant long-term reduction of congestive heart failure-related symptoms and thereby improves the quality of life in patients after MI.

Effect of ambulance 12-lead ECG recording on times to hospital reperfusion in acute myocardial infarction

OBJECTIVE

To review the evidence that recording a prehospital 12-lead electrocardiogram (ECG) reduces time from hospital arrival to initiation of reperfusion therapy for acute myocardial infarction (AMI).

DATA SOURCES

Medline search from 1966 to the present (articles in all languages) and examination of bibliographies.

STUDY SELECTION

Published studies of prehospital 12-lead ECG recording that included control groups and reported time intervals from hospital arrival to start of reperfusion therapy.

DATA EXTRACTION

Eight articles satisfied selection criteria (two randomised controlled trials, four non-randomised interventional studies and two prospective observational studies).

DATA SYNTHESIS

Widely varying study methodologies precluded meta-analysis. All studies had methodological problems, but hospital delays were consistently reduced. Such improvements appear to be small in hospitals where delays are already minimal.

CONCLUSIONS

Little evidence is available to support routine prehospital 12-lead ECG recording if the median hospital time to reperfusion is already less than 30 minutes. Improvement of in-hospital treatment times may be a better initial strategy than prehospital 12-lead ECG recording, as this will benefit more patients and allow ambulance services to better allocate their available resources.

A community hospital's effort to expedite treatment for patients with chest pain

OBJECTIVE

The purpose of this study was to determine treatment times at a community hospital that does not receive prehospital electrocardiogram (ECG) transmission and to determine the effect of time to first hospital ECG on overall door-to-drug time.

DESIGN

Descriptive.

SETTING

238-bed Regional Medical Center in Burlington, North Carolina.

SAMPLE

One hundred four patients with a final diagnosis of acute myocardial infarction were included in this 16-month study.

RESULTS

A median door-to-ECG time of 5 minutes was within the American College of Cardiology/American Heart Association recommendation of 10 minutes. Shorter treatment times to obtain the first ECG and initiate thrombolytic therapy were associated with younger patients and those arriving by ambulance.

CONCLUSIONS

While efficiency in obtaining a first hospital ECG on patients with suspected acute myocardial infarctions was achieved, this did not result in low door-to-drug times. Further streamlining of protocol and the exploration of prehospital initiatives may result in a significant reduction in door-to-drug times.

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.

Importance of time to reperfusion for 30-day and late survival and recovery of left ventricular function after primary angioplasty for acute myocardial infarction

OBJECTIVES

The purpose of this study was to evaluate the importance of time to reperfusion for outcomes after primary angioplasty for acute myocardial infarction.

BACKGROUND

Survival benefit of thrombolytic therapy for acute myocardial infarction is strongly dependent on time to treatment. Recent observations suggest that time to treatment may be less important for survival with primary angioplasty.

METHODS

Consecutive patients (n=1,352) with acute myocardial infarction treated with primary angioplasty were followed for up to 13 years. Paired acute and follow-up ejection fraction data were obtained at cardiac catheterization in 606 patients.

RESULTS

Reperfusion was achieved within 2 h in 164 patients (12%). Thirty-day mortality was lowest with early reperfusion (4.3% at <2 h vs. 9.2% at > or = 2 h, p=0.04) and was relatively independent of time to reperfusion after 2 h (9.0% at 2 to 4 h, 9.3% at 4 to 6 h, 9.5% at >6 h). Thirty-day-plus late cardiac mortality was also lowest with early reperfusion (9.1% at <2 h vs. 16.3% at > or = 2 h, p=0.02) and relatively independent at time to reperfusion after 2 h (16.4% at 2 to 4 h, 16.9% at 4 to 6 h, 15.6% at >6 h). Improvement in left ventricular ejection fraction was greatest in the early reperfusion group and relatively modest after 2 h (6.9% at <2 h vs. 3.1% at > or =2 h, p=0.007).

CONCLUSIONS

Time to reperfusion, up to 2 h, is important for survival and recovery of left ventricular function. After 2 h, recovery of left ventricular function is modest and survival is relatively independent of time to reperfusion. These data suggest that factors other than myocardial salvage may be responsible for survival benefit in patients treated with primary angioplasty after 2 h.

Call to needle times after acute myocardial infarction in urban and rural areas in northeast Scotland: prospective observational study

OBJECTIVE

To determine call to needle times and consider how best to provide timely thrombolytic treatment for patients with acute myocardial infarction.

DESIGN

Prospective observational study.

SETTING

City, suburban, and country practices referring patients to a single district general hospital in northeast Scotland.

SUBJECTS

1046 patients with suspected acute myocardial infarction given thrombolytic treatment.

MAIN OUTCOME MEASURES

Time from patients' calls for medical help until receipt of opiate or thrombolytic treatment, measured against a call to needle time of 90 minutes or less, as proposed by the British Heart Foundation.

RESULTS

General practitioners were the first medical contact in 97% (528/544) of calls by country patients and 68% (340/502) of city and suburban patients. When opiate was given by general practitioners, median call to opiate time was about 30 minutes (95% within 90 minutes) in city, suburbs, and country; call to opiate delay was about 60 minutes in city and suburban patients calling "999" for an ambulance. One third of country patients received thrombolytic treatment from their general practitioners with a median call to thrombolysis time of 45 minutes (93% within 90 minutes); this compares with 150 minutes (5% within 90 minutes) when this treatment was deferred until after hospital admission. In the city and suburbs, no thrombolytic treatment was given outside hospital, and only a minority of patients received it within 90 minutes of calling; median call to thrombolysis time was 95 (46% within 90 minutes) minutes.

CONCLUSIONS

The first medical contact after acute myocardial infarction is most commonly with a general practitioner. This contact provides the optimum opportunity to give thrombolytic treatment within the British Heart Foundation's guideline.