Causes of Prehospital Misinterpretations of ST Elevation Myocardial Infarction

Objectives: To determine the causes of software misinterpretation of ST elevation myocardial infarction (STEMI) compared to clinically identified STEMI to identify opportunities to improve prehospital STEMI identification. Methods: We compared ECGs acquired from July 2011 through June 2012 using the LIFEPAK 15 on adult patients transported by the Los Angeles Fire Department. Cases included patients ≥18 years who received a prehospital ECG. Software interpretation of the ECG (STEMI or not) was compared with data in the regional EMS registry to classify the interpretation as true positive (TP), true negative (TN), false positive (FP), or false negative (FN). For cases where classification was not possible using registry data, 3 blinded cardiologists interpreted the ECG. Each discordance was subsequently reviewed to determine the likely cause of misclassification. The cardiologists independently reviewed a sample of these discordant ECGs and the causes of misclassification were updated in an iterative fashion. Results: Of 44,611 cases, 50% were male (median age 65; inter-quartile range 52–80). Cases were classified as 482 (1.1%) TP, 711 (1.6%) FP, 43371 (97.2%) TN, and 47 (0.11%) FN. Of the 711 classified as FP, 126 (18%) were considered appropriate for, though did not undergo, emergent coronary angiography, because the ECG showed definite (52 cases) or borderline (65 cases) ischemic ST elevation, a STEMI equivalent (5 cases) or ST-elevation due to vasospasm (4 cases). The sensitivity was 92.8% [95% CI 90.6, 94.7%] and the specificity 98.7% [95% CI 98.6, 98.8%]. The leading causes of FP were ECG artifact (20%), early repolarization (16%), probable pericarditis/myocarditis (13%), indeterminate (12%), left ventricular hypertrophy (8%), and right bundle branch block (5%). There were 18 additional reasons for FP interpretation (<4% each). The leading causes of FN were borderline ST-segment elevations less than the algorithm threshold (40%) and tall T waves reducing the ST/T ratio below threshold (15%). There were 11 additional reasons for FN interpretation occurring ≤3 times each. Conclusion: The leading causes of FP automated interpretation of STEMI were ECG artifact and non-ischemic causes of ST-segment elevation. FN were rare and were related to ST-segment elevation or ST/T ratio that did not meet the software algorithm threshold.     

Prehospital Nitroglycerin Safety in Inferior ST Elevation Myocardial Infarction

Patients with inferior ST elevation myocardial infarction (STEMI), associated with right ventricular infarction, are thought to be at higher risk of developing hypotension when administered nitroglycerin (NTG). However, current basic life support (BLS) protocols do not differentiate location of STEMI prior to NTG administration. We sought to determine if NTG administration is more likely to be associated with hypotension (systolic blood pressure < 90 mmHg) in inferior STEMI compared to non-inferior STEMI. We conducted a retrospective chart review of prehospital patients with chest pain of suspected cardiac origin and computer-interpreted prehospital ECGs indicating “ACUTE MI.” We included all local STEMI cases identified as part of our STEMI registry. Univariate analysis was used to compare differences in proportions of hypotension and drop in systolic blood pressure ≥ 30 mmHg after nitroglycerin administration between patients with inferior wall STEMI and those with STEMI in another region (non-inferior). Multiple variable logistic regression analysis was also used to assess the study outcomes while controlling for various factors. Over a 29-month period, we identified 1,466 STEMI cases. Of those, 821 (56.0%) received NTG. We excluded 16 cases because of missing data. Hypotension occurred post NTG in 38/466 inferior STEMIs and 30/339 non-inferior STEMIs, 8.2% vs. 8.9%, p = 0.73. A drop in systolic blood pressure ≥ 30 mmHg post NTG occurred in 23.4% of inferior STEMIs and 23.9% of non-inferior STEMIs, p = 0.87. Interrater agreement for chart review of the primary outcome was excellent (κ = 0.94). NTG administration to patients with chest pain and inferior STEMI on their computer-interpreted electrocardiogram is not associated with a higher rate of hypotension compared to patients with STEMI in other territories. Computer interpretation of inferior STEMI cannot be used as the sole predictor for patients who may be at higher risk for hypotension following NTG administration.     

风险指数评估ST段抬高型心肌梗死患者危险性的护理意义

目的　探讨风险指数在评估ST段抬高型心肌梗死 (STEMI)患者预后中的护理意义。方法　对 4 0 8例确诊为STEMI患者的风险指数进行回顾性分析。风险指数按患者入院时的心率、收缩压、年龄用公式 {HR× (age/1 0 ) 2 } /SBP计算得出。结果　 (1 )随着年龄、心率和收缩压的增加 ,STEMI患者的风险指数和病死率亦随之增加(P <0 .0 5 )。 (2 )STEMI患者风险指数越大 ,住院期间死亡率越高。 (3)STEMI患者中存活组的风险指数明显低于死亡组 (P <0 .0 0 1 )。结论　STEMI患者风险指数与住院期间死亡率密切相关 ,是护士判断STEMI患者预后简便而可靠的方法     

Recurrent Syncope in a Patient After Myocardial Infarction

CREDNER, S.C., et al.: Recurrent Syncope in a Patient After Myocardial Infarction. A patient with ischemic cardiomyopathy presented with burning pain of his body surface with consecutive orthostatic intolerance and recurrent syncopes. A diagnosis of acute autonomic dysfunction was made and the patient was treated with midodrine, resulting in restoration of orthostatic tolerance after 6 weeks of therapy. (PACE 2003; 26[Pt. I]:920–921)     

急性ST段抬高型心肌梗死自发再灌注患者的临床及造影特点分析

目的探讨罪犯血管发生自发再灌注的急性ST段抬高型心肌梗死(STEMI)的临床及造影特点。方法将2006年1月至2009年12月在安贞医院28病房行直接经皮冠脉介入治疗(PCI)的STEMI患者519例,根据直接PCI术前罪犯血管TIMI血流分级,把患者分为自发再灌注组(TIMI血流Ⅲ级)和无自发再灌注组(TIMI血流0～Ⅱ级)。通过冠脉造影观察直接PCI前罪犯血管自发再灌注的发生率,并对其临床相关因素及造影病变特点进行分析。结果两组患者在年龄、CTnI峰值、≥2支血管病变高血栓负荷以及罪犯病变位于LAD部位方面的差异均有统计学意义(其P值分别为0.000、0.000、0.002、0.000和0.003)。而在性别、高血压、糖尿病、吸烟、高脂血症、既往心绞痛、罪犯血管分布、罪犯病变在LCX和RCA分布以及侧枝循环建立方面,其差异均无统计学意义(P值均>0.05)。结论与未发生自发再灌注的患者相比,自发再灌注的STEMI患者年龄较小,CTnI峰值较低,血栓负荷较重,罪犯病变多位于LAD远段。     

Electrocardiographic ST-segment Elevation The Diagnosis of Acute Myocardial Infarction by Morphologic Analysis of the ST Segment

Acute myocardial infarction (AMI) is one of many causes of ST-segment elevation (STE) in emergency department (ED) chest pain (CP) patients. The morphology of STE may assist in the correct determination of its cause, with concave patterns in non-AMI syndromes and non-concave waveforms in AMI. OBJECTIVES: To determine the impact of STE morphologic analysis on AMI diagnosis and the ability of this technique to separate AMI from non-infarction causes of STE. METHODS: The electrocardiograms (ECGs) of consecutive ED adult CP patients (with three serial troponin I determinations) were interpreted in two-step fashion by six attending emergency physicians (EPs): 1) the determination of STE by three EPs followed by 2) STE morphologic analysis (either concave or non-concave) in those patients with STE. The impact of STE morphology analysis was investigated in the identification of AMI and non-AMI causes of STE. Acute myocardial infarction was diagnosed by abnormal serum troponin I values (>0.1 mg/dL) followed by a rise and fall of the serum marker; STE diagnoses of non-AMI causes were determined by medical record review. Interobserver reliability concerning STE morphology was determined. Study inclusion criteria included at least three troponin values performed in serial fashion no more frequently than every three hours, initial ED ECG, ED diagnosis, and final hospital diagnosis. RESULTS: Five hundred ninety-nine CP patients were entered in the study, with 171 (29%) individuals having STE on their ECGs. Of the 171 patients who had STE, 56 had AMI, 50 had unstable angina pectoris (USAP), and 65 had non-coronary final diagnoses. Forty-nine patients had non-concave STE, 46 with AMI and three with USAP; no patient with a non-coronary diagnosis had a non-concave STE morphology. The sensitivity and specificity of the non-concave STE morphology for AMI diagnoses were 77% and 97%, respectively; the positive and negative predictive values for non-concave morphology in AMI diagnoses were 94% and 88%, respectively. Interobserver reliability in the STE morphology determination revealed a kappa coefficient of 0.87. CONCLUSIONS: A non-concave STE morphology is frequently encountered in AMI patients. While the sensitivity of this pattern for AMI diagnosis is not particularly helpful, the presence of this finding in adult ED chest pain patients with STE strongly suggests AMI. This technique produces consistent results among these EPs.     

Safety and Effectiveness of Field Nitroglycerin in Patients with Suspected ST Elevation Myocardial Infarction

Objective: While widely used in the treatment of cardiac conditions, only limited data characterize out-of-hospital nitroglycerin (NTG) use. We sought to determine the safety of out-of-hospital sublingual NTG administered for suspected ST-segment elevation myocardial infarction (STEMI) and its effect on the patient's pain score. Methods: We prospectively identified adult patients with suspected STEMI transported by paramedics to three percutaneous Coronary Intervention PCI-capable hospitals in a large urban-suburban emergency medical services (EMS) system. We compared patients who received field NTG to those who did not. The primary outcome was the change in systolic blood pressure (SBP) between initial EMS measurement and emergency department (ED) triage vital signs. Secondary outcomes included the frequency of hypotension (SBP < 100?mmHg) and bradycardia (HR < 60) on ED arrival, drop in SBP ≥ 30?mmHg, out-of-hospital cardiac arrest (OHCA), and the change in pain score compared to an a priori threshold of ?1.39. Results: Among 940 EMS transports for suspected STEMI, we excluded 160 for initial SBP < 100?mmHg, leaving 780 subjects for the analysis. Median age was 67 with 61% male. NTG was administered to 340 (44%) patients. The median change in SBP was ?10?mmHg (IQR ?27, 2) and ?3?mmHg (IQR ?20, 9) in patients treated with and without NTG, respectively. The median difference in the decrease in SBP was 6?mmHg (95% CI 3, 9?mmHg). The frequencies of ED hypotension and bradycardia, the drop in SBP ≥ 30?mmHg, and the OHCA did not differ between groups. For patients with an initial pain score > 0, the average change in pain score for patients treated with NTG was ?2.6 (95% CI ?3.0, ?2.2), while patients who did not receive NTG had a change in pain score of ?1.4 (95% CI ?1.8, ?1.0). Conclusion: In this cohort, field NTG did not result in a clinically significant decrease in blood pressure when compared with patients who did not receive NTG. However, NTG did cause a clinically significant reduction in pain.     

替罗非班对行急诊经皮冠状动脉介入治疗ST段抬高性心肌梗死患者心肌灌注和心功能的影响

目的:探讨ST段抬高性心肌梗死(STEMI)患者行急诊经皮冠状动脉介入治疗(PCI)中使用盐酸替罗非班对心肌灌注和心功能的影响。方法:将广东省人民医院心内科收治的120例STEMI患者随机分为观察组和对照组各60例,观察组于术中冠脉注射盐酸替罗非班(10μg/kg),对照组注射等量0.9%氯化钠。比较两组术后即时造影检查结果、术后校正TIMI帧数、磷酸肌酸激酶同工酶(CK-MB)峰值及峰值时间、术后2hST段回落程度及住院期间的出血并发症,比较两组术后7 d、30 d、90 d的左室舒张末期内径(LVEDD)、左室射血分数(EF)、左室收缩末期内径(LVESD)及术后90 d不良心血管事件(MACE)发生情况。结果:观察组患者术后即时造影、校正TIMI帧数、磷酸肌酸激酶同工酶峰值及到达峰值时间、术后2 h sT段回落程度均明显优于对照组(P0.05);观察组患者术后90 d MACE发生率明显低于对照组(P0.05),但住院期间出血并发症的发生率无明显差异(P0.05);观察组患者术后7 d、30 d、90 d的左室EF较对照组明显增加,LVEDD、LVESD较对照组明显降低(P0.05)。结论:STEMI患者行急诊PCI治疗中,给予冠脉注射盐酸替罗非班可有效减少慢血流、无复流的发生率,改善左室功能和心肌水平再灌注状态。     

Vasospasm-lnduced Myocardial Infarction With Sumatriptan

Sumatriptan, a 5-hydroxytryptamine¹ (5-HT₁) receptor agonist is an effective abortive agent for migraine headaches. A common side effect in 3% to 7.9% of patients is chest pain. Although most cases of chest pain are not thought to be of cardiac origin, its mechanism is not entirely understood. Rare examples of electrocardiogram changes consistent with transient ischemia have been reported. Isolated instances of angina, arrhythmia, myocardial infarction, and death have been temporally associated with sumatriptan administration. In most cases, it is unclear whether underlying cardiovascular disease existed or contributed to this adverse event. We report the history of a 56-year-old female patient with migraine who experienced myocardial infarction shortly after using sumatriptan, despite having had a normal cardiovascular evaluation. As she had a normal cardiac catheterization after the event, we find it probable that sumatriptan induced coronary vasospasm and myocardial infarction.     

Color Kinesis在识别心梗后存活心肌及判断冠脉病变的应用研究

本研究将Ｃｏｌｏｒ Ｋｉｎｅｓｉｓ（ＣＫ）与多巴酚丁胺超声心动图负荷试验（ＤＳＥ）相结合,检测急性心肌梗塞（ＡＭＩ）后存活心肌及冠脉病变。方法：左室彩和１６节段分法,室壁运动状态采用４级分法。存活心肌以ＰＴＣＡ２周后二维超声心动图（２ＤＥ）与ＤＳＥ ＢＡＳＥ状态２ＤＥ的比较结果作为参数标准;冠脉病变以冠脉造影结果作为金２ＤＥ相当（７５．０％ｖｓ７９．２％）,ＣＫ对ＬＣＸ病变仍有很高的敏感性（９０．     

Circadian Patterns of ST Elevation Myocardial Infarction in the New Millennium

Objective

Nearly four decades ago, a circadian pattern of acute myocardial infarction (AMI) with a peak in the early morning waking hours was described. The goal of the present study was to determine whether major changes in lifestyle and significant advances in medical therapy have altered this pattern in the intervening years.

Design

Retrospective chart review.

Setting

Tertiary care hospital in central Wisconsin.

Methods

We examined circadian patterns of ST elevation myocardial infarction (STEMI) in 519 patients diagnosed with STEMI over a 5-year period. Time of symptom onset was obtained from patient self-reports in the medical record and was recorded over 24 hours.

Results

We observed a circadian pattern of STEMI occurrence with a morning peak at approximately 11:30 AM. This pattern was highly significant in patients who were not using beta-blockers (P <0.0001) and had no history of diabetes (P <0.0001), but was otherwise absent. The circadian pattern appeared to be attenuated in patients of a younger age, female gender, or who used statins or aspirin. Peak STEMI occurrence was earlier in smokers than non-smokers.

Conclusions

Despite significant lifestyle changes and medical advances in the nearly four decades since a circadian pattern of AMI occurrence was first described, patients with STEMI had a circadian pattern of symptom onset with a morning peak. Use of beta-blockers and a history of diabetes mellitus abolished this pattern. Other modifying factors, including medications, age, and gender attenuated, but did not abolish, the circadian pattern.     

急性ST段抬高型心肌梗死合并血糖代谢异常患者预后分析

目的:总结急性ST段抬高型心肌梗死(STEMI)合并血糖代谢异常(2型糖尿病或就诊血糖升高)患者的预后。方法:回顾性分析2010年1月-2013年9月我科确诊STEMI患者413例的临床资料,比较血糖正常组(A组)与就诊血糖升高组(B组)、2型糖尿病组(C组)的预后。结果:(B+C)组住院期间死亡率明显高于A组(24.7%vs.9.4%,P0.05),C组住院期间再发心肌梗死率明显高于B组和A组(3.9%vs.0%vs.0.7%,P0.05),C组、B组与A组比较,再发心绞痛率(23.4%vs.31.0%vs.14.7%,P0.05)、住院期间心力衰竭率(41.6%vs.50.0%vs.22.1%,P0.05)、住院期间MACE(58.4%vs.65.5%vs.33.4%,P0.05)及一年全因死亡率(34.2%vs.31.4%vs.16.7%,P0.05)发生率更高。结论 :STEMI合并血糖代谢异常的预后差于血糖正常组。     

A Non-ST Elevation Myocardial Infarction Associated with Alternative Medicine Ozone Infusion

BackgroundAlternative medicine is frequently used by patients even though most treatments are without demonstrable benefit and have not been properly evaluated for medical safety. Intravenous ozone is a modern form of alternative medicine. Even though ozone has been used medically for more than a century, ozone as an infusion is scientifically untested and potentially dangerous. This case notes a patient who underwent an ozone infusion who experienced syncope and a non-ST elevation myocardial infarction immediately thereafter.Case ReportA 50-year-old white woman presented after experiencing syncope after completion of ozone infusion therapy. The ozone infusion consisted of her blood being drawn and ozone gas being injected into the sample. This blood was subsequently transfused back into the patient's blood stream via peripheral intravenous catheter. An initial electrocardiogram revealed no signs of infarction or ischemia, but her initial troponin I was elevated and continued to rise. She was admitted for a non-ST elevation myocardial infarction and underwent an extensive cardiac evaluation. It was determined that the oxidative myocardial stress secondary to ozone was associated with the non-ST elevation myocardial infarction.Why Should an Emergency Physician be Aware of This?More patients are turning to alternative medicine. Unfortunately, the published literature regarding intravenous ozone exposure is scant; however, a multitude of studies have shown that ozone can have hazardous effects, including that of detrimental cardiovascular oxidative stress. Emergency physicians need to be aware of these novel treatments and their potential undetermined effects.     

波立维联合脑心通治疗非ST段抬高型心肌梗死的疗效

目的探讨波立维联合脑心通治疗非ST段抬高型心肌梗死(NSTEMI)的临床效果。方法将60例NSTEMI患者按随机数字表法分为观察组和对照组,对照组30例给予常规综合治疗措施,观察组30例在常规综合治疗基础上同时给予波立维联合脑心通治疗,评估两者治疗效果。结果治疗后观察组患者CK、CK-MB及cTnT水平均低于对照组(P<0.05)。观察组显效率、总有效率明显高于对照组,2组比较差异有统计学意义(P<0.05)。结论波立维联合脑心通治疗非ST段抬高型心肌梗死的临床效果明确,值得应用。     

氯吡格雷治疗急性非ST段抬高心肌梗死的临床观察

目的：观察氯吡格雷治疗急性非ST段抬高心肌梗死（NSTEMI）的临床疗效及安全性。方法：急性非ST段抬高心肌梗死（NsrITEMI）60例随机分为治疗组和对照组,对照组采用低分子肝素、阿司匹林及其他抗心绞痛药物,治疗组在以上治疗的基础上加用氯吡格雷首次顿服300mg,次日起75mg／d,连服2周。结果：治疗组能明显减少心绞痛发作频率（P〈0．05）,改善临床症状,对改善缺血性ST段压低明显优于对照组（P〈0．05）,且对出、凝血指标影响不大（P〉0．05）。结论：在常规抗心绞痛治疗基础上加用氯吡格雷对NSTEMI安全有效。     

Acute ST Elevation Myocardial Infarction Due to Allergic Reaction,Kounis Syndrome

Kounis syndrome is defined by the occurrence of an acute coronary syndrome (ACS) in the setting of an allergic, hypersensitivity or anaphylactic condition. Degranulation of mast cells and platelet activation leading to the release of multiple inflammatory mediators are thought to make the arterial circulation susceptible to acute cardiac events. It is an often underdiagnosed entity in the emergency setting, due to lack of awareness among emergency providers. Identifying Kounis syndrome is critical, since managing ACS differs from that of a classical acute myocardial infarction. We present the case of a 72-year old male patient with a history of stable coronary disease who presented to the emergency department with a diffuse pruritic rash and chest pain. Electrocardiogram showed ST elevation myocardial infarction. Urgent coronary angiography revealed total occlusion of the mid left anterior descending coronary artery which was treated with a drug eluting stent with an excellent outcome. The pruritic rash responded to treatment with intravenous corticosteroids and antihistamines; No allergens were identified. The patient’s symptoms resolved and he had an uneventful hospitalization.The diagnosis of Kounis syndrome can complicate the management of acute allergic reactions. Special precautions should be taken by emergency physicians with regards to the administration of beta blockers, morphine and vasodilators, which may be detrimental in this setting.     

Implementation of Specialty Centers for Patients with ST-Segment Elevation Myocardial Infarction

Background. Early percutaneous coronary intervention (PCI) has been shown to be superior to fibrinolytic therapy andis associated with reduced morbidity andmortality for patients with ST-segment elevation myocardial infarction (STEMI). Objective. To determine the performance of a regional system with prehospital 12-lead electrocardiogram (ECG) identification of STEMI patients anddirect paramedic transport to STEMI receiving centers (SRCs) for provision of primary PCI. Methods. This was a prospective study evaluating the first year of implementation of a regional SRC network to determine the key time intervals for patients identified with STEMI in the prehospital setting. Results. During the 12-month study period, 1,220 patients with a suspected STEMI were identified on prehospital 12-lead ECG, of whom 734 (60%) underwent emergency PCI. A door-to-balloon time of 90 minutes or less was achieved for 651 (89%) patients, and459 (62.5%) had EMS–patient contact-to-balloon times ≤ 90 minutes. Transport of suspected STEMI patients to an SRC resulted in ambulance diversion from a closer ED for 31% of patients anda median increase in transport time of 3.8 minutes. Conclusion. Door-to-balloon times within the 90-minute benchmark were achieved for almost 90% of STEMI patients transported by paramedics after implementing our regionalized SRC system     

Emergency Medical Services Utilization among Patients with ST-Segment Elevation Myocardial Infarction: Observations from the Singapore Myocardial Infarction Registry

Objective: Early activation of emergency medical services (EMS), rapid transport, and treatment of patients experiencing ST-segment elevation myocardial infarction (STEMI) can improve outcomes. The Singapore Myocardial Infarction Registry (SMIR) is a nation-wide registry that collects data on STEMI. We aimed to determine the prevalence, predictors, and outcomes of EMS utilization among STEMI patients presenting to Emergency Departments (ED) in Singapore. Methods: We analyzed STEMI patients enrolled by SMIR from January 2010 to December 2012. We excluded patients who were transferred, developed STEMI in-hospital or suffered cardiac arrest out-of-hospital or in the ED. Primary outcome was process-of-care timings. Secondary outcomes included the occurrence of cardiac complications. Multivariate analysis was used to examine independent factors associated with EMS transport. Results: 6412 patients were enrolled into the study; 4667 patients were eligible for analysis. 49.8% of patients utilized EMS transport. EMS transport was associated with higher rate of reperfusion therapy (74.3% vs. 65.1%, p < 0.01), shorter median symptom-to-door time (119 vs. 182 minutes, p < 0.01), door-to-balloon time (59 vs. 70 minutes, p < 0.01), and symptom-to-balloon time (185 vs. 233 minutes, p < 0.01). EMS transport had more patients with Killip Class 4 (7.5% vs 4.0%, p < 0.01) and was associated with greater presentation of heart failure, arrhythmias, and complete heart block. Independent predictors of EMS transport were age, syncope and Killip score; after-office-hour presentation was a negative predictor. Conclusion: Less than half of STEMI patients utilized EMS and EMS patients had faster receipt of initial reperfusion therapies. Targeted public education to reduce time to treatment may improve the care of STEMI patients.