Thrombolysis after acute myocardial infarction: Are Canadian physicians up to the challenge?

Acute myocardial infarction (AMI) evolves as a time-dependent wave front of ischemia when the abrupt rupture of an unstable fatty plaque initiates coronary thrombosis. The prospect of salvaging potentially viable myocardial tissue has led to the development of reperfusion strategies using thrombolytic agents. The efficacy of thrombolytic therapy is determined in large measure by the speed with which it is initiated. It is therefore vital to minimize the "door-to-needle" time once a patient with AMI arrives at the emergency department. In this issue (see pages 497 to 505) Dr. Jafna L. Cox and associates report that Canadian centres participating in the GUSTO-I trial were significantly slower to initiate thrombolytic therapy than their US counterparts. In this editorial Cox and associates'' report is reviewed against the background of similar trials, and strategies to minimize delays in the initiation of thrombolytic therapy are suggested.     

Effect of "fast track" admission for acute myocardial infarction on delay to thrombolysis.

OBJECTIVE--To evaluate the impact of a fast track triage system for patients with acute myocardial infarction. DESIGN--Comparison of delays in admission to hospital and in receiving thrombolytic treatment before and after introducing fast track system with delays recorded in 1987-8. Patients fulfilling clinical and electrocardiographic criteria for myocardial infarction were selected for rapid access to the cardiac care team, bypassing evaluation by the medical registrar. SETTING--Major accident and emergency, cardiac and trauma centre. SUBJECTS--359 patients admitted to the cardiac care unit during 1 February to 31 July 1990 with suspected acute infarction. MAIN OUTCOME MEASURES--Accuracy of diagnosis and delay from arrival at hospital to thrombolytic treatment. RESULTS--248 of the 359 patients had myocardial infarction confirmed, of whom 127 received thrombolytic treatment. The fast track system correctly identified 79 out of 127 (62%) patients who subsequently required thrombolytic treatment. 95% (79/83) of patients treated with thrombolysis after fast track admission had the diagnosis confirmed by electrocardiography and enzyme analysis. The median delay from hospital admission to thrombolytic treatment fell from 93 minutes in 1987-8 to 49 minutes in fast track patients (p less than 0.001). Delay in admission to the cardiac care unit was reduced by 47% for fast tract patients (median 60 minutes in 1987-8 v 32 minutes in 1990, p less than 0.001) and by 25% for all patients (60 minutes v 45 minutes, p less than 0.001). CONCLUSION--This fast track system requires no additional staff or equipment, and it halves inhospital delay to thrombolytic treatment without affecting the accuracy of diagnosis among patients requiring thrombolysis.     

Tuesday morning rounds

Survival in the acute phase of myocardial infarction and the subsequent prognosis are critically dependent on the time between onset of symptoms and medical intervention. Studies have shown that the time that patients take to decide to seek help accounts for most of the delay. We documented the length of time from onset of symptoms to arrival in hospital for 201 patients consecutively admitted to one of four hospitals in the Regional Municipality of Ottawa-Carleton between October 1986 and February 1987 for suspected acute myocardial infarction. Of the 160 survivors 42% waited more than 4 hours (a critical time for effective thrombolytic therapy) before coming to hospital, and nearly a third did not arrive within 6 hours. On the basis of interviews conducted with 42 patients, sociodemographic factors, education, past experience with an acute myocardial infarction, a previous diagnosis of angina and a coronary-prone behaviour pattern did not explain the delay. How patients perceived the seriousness of their symptoms and how they used other illness-related coping strategies explained 46% of the variance in the delay. Interventions aimed at reducing the delay between onset of symptoms and treatment must focus on patients'' preadmission behaviour.     

Standardised pre-hospital care of acute myocardial infarction patients: MISSION! guidelines applied in practice

Background. To improve acute myocardial infarction (AMI) care in the region ‘Hollands-Midden’ (the Netherlands), a standardised guideline-based care program was developed (MISSION!). This study aimed to evaluate the outcome of the pre-hospital part of the MISSION! program and to study potential differences in pre-hospital care between four areas of residency. Methods. Time-to-treatment delays, AMI risk profile, cardiac enzymes, hospital stay, in-hospital mortality, and pre-AMI medication was evaluated in consecutive AMI patients (n=863, 61±13years, 75% male) transferred to the Leiden University Medical Center for primary percutaneous coronary intervention (PCI). Results. Median time interval between onset of symptoms and arrival at the catheterisation laboratory was 150 (interquartile range [IQR] 101-280) minutes. The alert of emergency services to arrival at the hospital time was 48 (IQR 40-60) minutes and the door-to-catheterisation laboratory time was 23 (IQR 13-42) minutes. Despite significant regional differences in ambulance transportation times no difference in total time from onset of symptoms to arrival at the catheterisation room was found. Peak troponin T was 3.33 (IQR 1.23-7.04) µg/l, hospital stay was 2 (IQR 2-3) days and in-hospital mortality was 2.3%. Twelve percent had 0 known risk factors, 30% had one risk factor, 45% two to three risk factors and 13% had four or more risk factors. No significant differences were observed for AMI risk profiles and medication pre-AMI. Conclusions. This study shows that a standardised regional AMI treatment protocol achieved optimal and uniformly distributed pre-hospital performance in the region ‘Hollands-Midden’, resulting in minimal time delays regardless of area of residence. Hospital stay was short and in-hospital mortality low. Of the patients, 88% had ≥1 modifiable risk factor. (Neth Heart J 2010;18:408-15.)     

Recommendations for ensuring early thrombolytic therapy for acute myocardial infarction. The Heart and Stroke Foundation of Canada,the Canadian Cardiovascular Society and the Canadian Association of Emergency Physicians for the Emergency Cardiac Care Coalition.

OBJECTIVE: To recommend practical steps to ensure early thrombolytic therapy and thereby reduce mortality and morbidity associated with acute myocardial infarction (AMI). OPTIONS: Various factors were considered that influence time to thrombolysis related to patients, independent practitioners and health care systems. OUTCOMES: Reduction in morbidity and mortality associated with AMI. EVIDENCE: Early initiation of thrombolytic therapy reduces morbidity and mortality associated with AMI. The ECC Coalition analysed the factors that might impede early implementation of thrombolytic therapy. VALUES: Published data were reviewed, and recommendations were based on consensus opinion of the Emergency Cardiac Care (ECC) Coalition. The ECC Coalition comprises 20 professional, nongovernment and government organizations and has a mandate to improve emergency cardiac care services through collaboration. BENEFITS, HARMS AND COSTS: Early thrombolytic therapy reduces morbidity and mortality associated with AMI. Implementation of the recommendations will result in reduced time to thrombolytic therapy, streamlining of current practices and enhanced cooperation among health care professionals to expedite care. Depending on existing practices, implementation may require protocol development, and public and professional education. Although costs are associated with educating the public and health care professionals, they are outweighed by the financial and social benefits of reduced morbidity and mortality. RECOMMENDATIONS: Early recognition of AMI symptoms by the public and health care professionals, early access to the emergency medical services system and early action by emergency care providers in administering thrombolytic therapy (within 30 minutes after the patient''s arrival at the emergency department). VALIDATION: No similar consensus statements or practice guidelines for thrombolytic therapy in Canada are available for comparison.     

Initiating thrombolytic therapy for acute myocardial infarction: whose job is it anyway?

Although thrombolytic therapy has clearly become the standard of care for acute myocardial infarction (AMI), its delivery in Canada continues to be extremely variable. Significant unnecessary delays in the initiation of this treatment still occur in many hospitals and constitute the most common avoidable cause of death in patients with AMI. The authors agree with the statement by representatives of the member organizations of the Emergency Cardiac Care Coalition (see pages 483 to 487 of this issue) that emergency service providers must get patients to hospital sooner and that all eligible patients should receive thrombolytic therapy within 30 minutes of their arrival at hospital. This objective requires that thrombolytic therapy be initiated by emergency physicians and be supported by well-established guidelines for its use.     

静脉溶栓时机对急性ST段抬高型心肌梗死患者溶栓效果及主要不良心脏事件发生率的影响

目的:探讨静脉溶栓时机对急性ST段抬高型心肌梗死患者溶栓效果及主要不良心脏事件发生率的影响。方法:将2016年1月至2017年12月我院接诊的314例急性ST段抬高型心肌梗死患者纳入本研究,按照溶栓治疗时间不同分为A组(发病至溶栓时间6 h)172例、B组(发病至溶栓时间为6～12 h)102例和C组(发病至溶栓时间12 h)40例,比较三组患者溶栓效果、溶栓后ST段回落情况以及住院期间主要不良心脏事件发生情况。结果:A组患者梗死冠脉溶通率、溶栓后ST段回落幅度高于B组和C组,且B组高于C组,差异均有统计学意义(P0.05)。A组患者治疗后ST段回落最大幅度所需时间、住院期间主要不良心脏事件总发生率低于B组和C组,且B组低于C组,差异均有统计学意义(P0.05)。结论:急性ST段抬高型心肌梗死患者发病后6 h内静脉溶栓治疗梗死冠脉溶通率更高、ST段回落效果更好,可降低住院期间主要不良心脏事件发生风险。     

Dietary intake of carotenoids and retinol and the risk of acute myocardial infarction in Italy

BACKGROUND: Carotenoids may reduce the risk of coronary heart disease through their antioxidant properties, but the results of epidemiological studies are controversial. We analysed the relation between the intake of selected carotenoids and retinol and risk of acute myocardial infarction (AMI). METHODS: A case-control study was conducted in Milan, Italy, in 1995-2003. Cases were 760 patients with nonfatal AMI, and controls 682 patients admitted to hospital. RESULTS: The risk of AMI decreased with increasing intake of alpha-carotene (odds ratios, OR = 0.71, 95% confidence intervals, CI 0.51-0.98, for the highest vs the lowest quartile of intake), beta-carotene (OR = 0.71, 95% CI 0.50-1.01) and beta-criptoxanthin (OR = 0.64, 95% CI 0.46-0.88). No associations emerged for total carotenoids, lycopene, lutein plus zeaxanthin and retinol. CONCLUSIONS: Our study suggests a weak protective effect of alpha-carotene, beta-carotene and beta-criptoxanthin on the risk of AMI. It also indicates that total carotenoids, lycopene, lutein plus zeaxanthin and retinol were not related to the risk of the disease.     

Feasibility,safety, and efficacy of domiciliary thrombolysis by general practitioners: Grampian region early anistreplase trial. GREAT Group.

OBJECTIVE--To assess the feasibility, safety, and efficacy of domiciliary thrombolysis by general practitioners. DESIGN--Randomised double blind parallel group trial of anistreplase 30 units intravenously and placebo given either at home or in hospital. SETTING--29 rural practices in Grampian admitting patients to teaching hospitals in Aberdeen (average distance 36 (range 16-62) miles). PATIENTS--311 patients with suspected acute myocardial infarction and no contraindications to thrombolytic therapy seen at home within four hours of onset of symptoms. MAIN OUTCOME MEASURES--Time saving, adverse events, Q wave infarction, left ventricular function. RESULTS--Anistreplase was administered at home 101 minutes after onset of symptoms, while anistreplase was given in hospital 240 minutes after onset of symptoms (median times). Adverse events after thrombolysis were infrequent and, apart from cardiac arrest, not a serious problem when they occurred in the community: seven of 13 patients were resuscitated after cardiac arrest out of hospital. By three months after trial entry the relative reduction of deaths from all causes in patients given thrombolytic therapy at home was 49% (13/163 (8.0%) v 23/148 (15.5%); difference -7.6% (95% confidence interval -14.7% to -0.4%), p = 0.04). Full thickness Q wave infarction was less common in patients with confirmed infarction receiving treatment at home (65/122 (53.3%) v 76/112 (67.9%); difference -14.6% (95% confidence interval -27.0% to -2.2%), p = 0.02). CONCLUSIONS--General practitioners provided rapid pre-hospital coronary care of a high standard. Compared with later administration in hospital, giving anistreplase at home resulted in reduction in mortality, fewer cardiac arrests, fewer Q wave infarcts, and better left ventricular function. Benefits were most marked where thrombolytic therapy was administered within two hours of the onset of symptoms.     

Resuscitation from cardiac arrest: assessment of a system providing only basic life support outside of hospital

Resuscitation outside of hospital of victims of cardiac arrest is a major challenge to our emergency care system. Most cities in Canada do not have a mobile advanced life support service; instead they rely on basic life support outside of hospital. The outcome in such cases and the factors affecting the outcome are largely unknown. Thus, it is difficult to estimate the lifesaving potential of adding advanced life support to the existing measures available for care outside of hospital.A prospective study of all resuscitation attempts begun outside of hospital was conducted during 18 consecutive months in 1977-78 in Winnipeg; at that time only basic life support was available outside of hospital. Resuscitation was attempted 849 times, and 33 patients (4%) survived to be discharged from hospital. Data analysis revealed that: (a) none of the 58% of patients in asystole at the time of arrival at a hospital survived to be discharged, but 11% of the patients with ventricular fibrillation or tachycardia (27% of the entire group) survived; (b) the survival rate was lower when the interval from the emergency telephone call to the patient''s arrival at the hospital exceeded 10 minutes; and (c) basic life support was begun immediately in 29% of the patients with ventricular fibrillation or tachycardia, and increased the survival rate fivefold.The training of private citizens in basic life support is a vital component of total emergency cardiac care. A mobile advanced life support service will be effective in saving lives if it reduces the delay before definitive care is instituted, preferably to less than 10 minutes.     

Myocardial Infarction Occurs with a Similar 24 h Pattern in the 4G/5G Versions of Plasminogen Activator Inhibitor-1

PAI-1 expression is regulated by a 4G/5G promoter polymorphism. The 4G allele is associated with greater circadian variation of PAI-1 levels. We hypothesized that the 24 h variation of cardiac risk is more pronounced among persons with the 4G4G genotype than among ones with 4G5G and 5G5G genotypes. We assessed the time of onset of symptoms in 623 consecutive patients with acute myocardial infarction (AMI) enrolled in the MISSION! Study between February 1, 2004, and October 29, 2006. All of the patients were genotyped for the PAI-1 4G/5G polymorphism. We quantified the amplitude of the 24 h variation of AMI with a generalized linear model with Poisson distribution. A morning peak, between 06:00–11:59 h (n?=?197; 32% of all cases), in the onset of symptoms of AMI was observed. The group composed of patients with the 4G4G genotype did not have a more pronounced morning peak than the groups composed of other genotypes; the 24 h variation was 38% (95% confidence interval 12–70%) in the group of 4G4G patients and 34% (14–58%) and 56% (20–100%) in the 4G5G and 5G5G groups of patients, respectively. Our findings show that 24 h variation of cardiac risk is not more pronounced among the 4G4G genotype of PAI-1. (Author correspondence: j.g.vanderbom@lumc.nl)     

Time delays in provision of thrombolytic treatment in six district hospitals. Joint Audit Committee of the British Cardiac Society and a Cardiology Committee of Royal College of Physicians of London.

OBJECTIVE--To measure the delays between onset of symptoms and admission to hospital and provision of thrombolysis in patients with possible acute myocardial infarction. DESIGN--Observational study of patients admitted with suspected myocardial infarction during six months. SETTING--Six district general hospitals in Britain. SUBJECTS--1934 patients admitted with suspected myocardial infarction. MAIN OUTCOME MEASURES--Route of admission to hospital and time to admission and thrombolysis. RESULTS--Patients who made emergency calls did so sooner after onset of symptoms than those who called their doctor (median time 40 (95% confidence interval 30 to 52) minutes v 70 (60 to 90) minutes). General practitioners took a median of 20 (20 to 25) minutes to visit patients, rising to 30 (20 to 30) minutes during 0800-1200. The median time from call to arrival in hospital was 41 (38 to 47) minutes for patients who called an ambulance from home and 90 (90 to 94) minutes for those who contacted their doctor. The median time from arrival at hospital to thrombolysis was 80 (75 to 85) minutes for patients who were treated in the cardiac care unit and 31 (25 to 35) minutes for those treated in the accident and emergency department. CONCLUSION--The time from onset of symptoms to thrombolysis could be reduced substantially by more effective use of emergency services and faster provision of thrombolysis in accident and emergency departments.     

Patient and general practitioner delays in acute myocardial infarction

The longest component of the total delay in coming under coronary care is patient delay, and it has been suggested that public education might be used to make it shorter. The patterns of patient delay were studied in 450 patients with acute myocardial infarction uncomplicated by cardiac arrest out of hospital, of whom 243 had a previous history of ischaemic heart disease. Patient delays had a skewed distribution with a modal delay of up to one hour, a median delay of two hours, and a mean delay of 10 hours. Two thirds of patients had sought help from their general practitioners within four hours of the onset of symptoms. During the first four hours the longer that patients delayed the lower was the subsequent mortality (27%, 18%, and 9% for delays of one hour or less, up to two hours, and up to four hours, respectively), but patients who delayed four to eight hours had the highest mortality of all (38%). Neither the median value nor the pattern of patient delays was altered by a previous history of ischaemic heart disease.There were pronounced differences in doctor delays, depending on the patient''s age, delay time, and ultimate place of treatment, showing that the doctors'' behaviour was influenced before they had seen their patients. Nevertheless, the median total delay for patients aged up to 70 was one hour 35 minutes, and a higher proportion of patients were seen early after infarction than in recent hospital trials of thrombolytic treatment.These findings suggest that the patients'' call for help and the doctors'' response may be at an instinctive level according to the patients'' distress; these patterns of behaviour may be difficult to modify by public education.     

A multicentre observational study of presentation and early assessment of acute stroke

ObjectiveTo investigate delays in the presentation to hospital and evaluation of patients with suspected stroke.DesignMulticentre prospective observational study.Setting22 hospitals in the United Kingdom and Dublin.Participants739 patients with suspected stroke presenting to hospital.ResultsThe median age of patients was 75 years, and 400 were women. The median delay between onset of symptoms and arrival at hospital was 6 hours (interquartile range 1 hour 48 minutes to 19 hours 12 minutes). 37% of patients arrived within 3 hours, 50% within 6 hours. The median delay for patients using the emergency service was 2 hours 3 minutes (47 minutes to 7 hours 12 minutes) compared with 7 hours 12 minutes (2 hours 5 minutes to 20 hours 37 minutes) for referrals from general practitioners (P<0.0001). Use of emergency services reduced delays to hospital (odds ratio 0.45, 95% confidence interval 0.23 to 0.61). The median time to evaluation by a senior doctor was 1 hour 9 minutes (interquartile range 33 minutes to 1 hour 50 minutes) but was undertaken in only 477 (65%) patients within 3 hours of arrival. This was not influenced by age, sex, time of presentation, mode of referral, hospital type, or the presence of a stroke unit. Computed tomography was requested within 3 hours of arrival in 166 (22%) patients but undertaken in only 60 (8%).ConclusionDelays in patients arriving at hospital with suspected stroke can be reduced by the increased use of emergency services. Over a third of patients arrive at hospital within three hours of stroke; their management can be improved by expediting medical evaluation and performing computed tomography early.

What is already known on this topic

Delay in presentation and assessment of patients with suspected stroke prevents the possible benefits from thrombolysis being achievedLittle is known about the presentation and early management of patients with acute stroke in the United Kingdom

What this study adds

Most patients with suspected stroke in the United Kingdom arrive at hospital within six hours of the onset of symptomsNot all patients are evaluated by a senior doctor within three hours of arrival at hospital and most do not undergo computed tomographyThe potential for thrombolysis in patients with acute stroke can be improved significantly by greater use of emergency services and expediting evaluation and investigations by doctors     

Evaluation of a multicomponent intervention to shorten thrombolytic door-to-needle time in stroke patients in China (MISSION): A cluster-randomized controlled trial

BackgroundRapid intravenous thrombolysis (IVT) for acute ischemic stroke (AIS) is crucial for improving outcomes. However, few randomized trials of interventions aimed at reducing in-hospital delay have been carried out in China. We aimed to evaluate the effect of a multicomponent intervention on thrombolytic door-to-needle time (DNT) of AIS patients via video teleconference based on the Behavior Change Wheel (BCW) method.Methods and findingsThis cluster-randomized trial, conducted between January 1, 2019 and December 31, 2019, randomly allocated 22 hospitals equally to PEITEM (Persuasion Environment reconstruction Incentivization Training Education Modeling) intervention or routine care plus stroke registry and subsequently enrolled 1,634 AIS patients receiving IVT within 4.5 hours upon stroke onset from participant hospitals. The PEITEM group received a 1-year PEITEM 6-component intervention based on the behavioral theory monthly via video teleconference. The primary outcome was the proportion of patients with a DNT of 60 minutes or less. A total of 987 patients participated in the PEITEM group (mean age, 69 years; female, 411 [41.6%]) and 647 patients in the control group (mean age, 70 years; female, 238 [36.8%]). Of all participants, the proportion of DNT ≤60 minutes in the PEITEM group was higher than in the control group (82.0% versus 73.3%; adjusted odds ratio, 1.77; 95% confidence interval (CI), 1.17 to 2.70; ICC, 0.04; P = 0.007). Among secondary outcomes, the average DNT was 43 minutes in the PEITEM group and 50 minutes in the control group (adjusted mean difference: −8.83; 95% CI, −14.03 to −3.64; ICC, 0.12; P = 0.001). Favorable functional outcome (score of 0 to 1 on the modified Rankin scale (mRS)) was achieved in 55.6% patients of the PEITEM group and 50.4% of the control group (adjusted odds ratio, 1.38; 95% CI, 1.00 to 1.90; ICC, 0.01; P = 0.049). Main study limitations include non-blinding of clinicians, and that specific interventions component responsible for the observed changes could not be determined.ConclusionsThe teleconference-delivered PEITEM intervention resulted in a moderate but clinically relevant shorter DNT and better functional outcome in AIS patients receiving IVT.Trial registrationClinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT03317639","term_id":"NCT03317639"}}NCT03317639.

Wansi Zhong and co-workers study an intervention aimed at improving delivery of prompt thrombolytic treatment for ischemic stroke in China.     

Building a "brain attack" team to administer thrombolytic therapy for acute ischemic stroke

Before tissue plasminogen activator (tPA) was licensed for use in Canada, in February 1999, the Calgary Regional Stroke Program spearheaded the development and organization of local resources to use thrombolytic therapy in patients who had experienced acute ischemic stroke. In 1996 special permission was obtained from the Calgary Regional Health Authority to use intravenously administered tPA for acute ischemic stroke, and ethical and scientific review boards approved the protocols. After 3 years our efforts have resulted in improved patient outcomes, shorter times from symptom onset to treatment and acceptable adverse event rates. Areas for continued improvement include the door-to-needle time and broader education of the public about the symptoms of acute ischemic stroke.     

Modeling the Cost Effectiveness of Neuroimaging-Based Treatment of Acute Wake-Up Stroke

Background

Thrombolytic treatment (tissue-type plasminogen activator [tPA]) is only recommended for acute ischemic stroke patients with stroke onset time <4.5 hours. tPA is not recommended when stroke onset time is unknown. Diffusion-weighted MRI (DWI) and fluid attenuated inversion recovery (FLAIR) MRI mismatch information has been found to approximate stroke onset time with some accuracy. Therefore, we developed a micro-simulation model to project health outcomes and costs of MRI-based treatment decisions versus no treatment for acute wake-up stroke patients.

Methods and Findings

The model assigned simulated patients a true stroke onset time from a specified probability distribution. DWI-FLAIR mismatch estimated stroke onset <4.5 hours with sensitivity and specificity of 0.62 and 0.78, respectively. Modified Rankin Scale (mRS) scores reflected tPA treatment effectiveness accounting for patients’ true stroke onset time. Discounted lifetime costs and benefits (quality-adjusted life years [QALYs]) were projected for each strategy. Incremental cost-effectiveness ratios (ICERs) were calculated for the MRI-based strategy in base-case and sensitivity analyses. With no treatment, 45.1% of simulated patients experienced a good stroke outcome (mRS score 0–1). Under the MRI-based strategy, in which 17.0% of all patients received tPA despite stroke onset times >4.5 hours, 46.3% experienced a good stroke outcome. Lifetime discounted QALYs and costs were 5.312 and $88,247 for the no treatment strategy and 5.342 and $90,869 for the MRI-based strategy, resulting in an ICER of $88,000/QALY. Results were sensitive to variations in patient- and provider-specific factors such as sleep duration, hospital travel and door-to-needle times, as well as onset probability distribution, MRI specificity, and mRS utility values.

Conclusions

Our model-based findings suggest that an MRI-based treatment strategy for this population could be cost-effective and quantifies the impact that patient- and provider-specific factors, such as sleep duration, hospital travel and door-to-needle times, could have on the optimal decision for wake-up stroke patients.     

Role of patient chronotype on circadian pattern of myocardial infarction: a pilot study

Population-based studies indicate the risk of acute myocardial infarction (AMI) is greatest in the morning, during the initial hours of diurnal activity. The aim of this pilot study was to determine whether chronotype, i.e., morningness and eveningness, impacts AMI onset time. The sample comprised 63 morning- and 40 evening-type patients who were classified by the Horne-?stberg Morningness-Eveningness Questionnaire (MEQ) in the hospital after experiencing the AMI. The average wake-up and bed times of morning types were ~2?h earlier than evening types. Although the lag in time between waking up from nighttime sleep and AMI onset during the day did not differ between the two chronotypes, the actual clock-hour time of the peak in the 24-h AMI pattern did. The peak in AMI of morning types occurred between 06:01 and 12:00?h and that of the evening types between 12:01 and 18:00?h. Although the results of this small sample pilot study suggest one's chronotype influences the clock time of AMI onset, larger scale studies, which also include assessment of 24-h patterning of events in neither types, must be conducted before concluding the potential influence of chronotype on the timing of AMI onset.     

常见血清酶测定在急性心肌梗塞诊断中的应用

对1992年6月至1993年4月入院诊断为急性心肌梗塞(AMI)患者在发病后即时至48 h分三个阶段进行连续取血样测定4种血清酶（AST、CK、LDH、CKMB）的含量,且与心电图作比较.结果表明,在AMI过程中酶异常检出率最高可达到90%（AST、CK-MB）,最低为70%（LDH）.若以异常Q波为AMI确诊,其不能检出率为40%;提示在AMI早期作血清酶检测有助于进一步确诊及减少漏诊率.若AMI患者已下降的CK-MB再度上升,提示可能有新的梗死灶发生;AMI患者在发病6 h内,血清酶显著升高,提示预后不佳.