Serial Electrocardiograms for Chest Pain Patients with Initial Nondiagnostic Electrocardiograms: Implications for Thrombolytic Therapy

Objectives: To determine the proportion of acute myocardial infarction (AMI) patients without ST–segment elevation who subsequently develop ST–segment elevation during their hospital courses; and to compare demographics and presenting features of AMI patient subgroups: those with initial ST–segment elevation, those with in–hospital ST–segment elevation, and those with no ST–segment elevation. Methods: A retrospective cohort analysis of admitted chest pain patients who had a hospital discharge diagnosis of AM1 was performed. Each chart was examined for initial ECG interpretation, serial ECG analysis, patient age, gender, cardiac risk factors, in-hospital survival, time between sequential ECGs, and number of ECGs performed within the first 48 hours of hospital admission. Results: Of the 114 charts reviewed, 20 patients had ECGs meeting thrombolytic criteria on arrival. Of the 94 AM1 patients who had nondiagnostic ECGs on arrival, 19 (20%) subsequently developed ECG changes meeting thrombolytic criteria. Seven patients developed these changes within eight hours of the initial ECG, four from eight to 12 hours after, two from 12 to 24 hours after, and six more than 24 hours after. Most patients who had documented AMIs did not develop ECG criteria for thrombolytic therapy during their hospitalizations. Male gender and smoking history were more commonly associated with late ST-segment elevation for those presenting with nondiagnostic ECGs. All the patients who had late diagnostic ECG changes survived to hospital discharge. Serial ECGs were performed more frequently in the group who had initially diagnostic ECGs and least frequently in the group who did not develop ST-segment elevation during their hospitalizations. Conclusions: Most patients with AM1 do not meet ECG criteria for the administration of thrombolytic therapy. A significant minority (20%) of the admitted chest pain patients with subsequently confirmed AMIs developed ECG criteria for thrombolytics during their hospitalizations. Further attention to such patients who have delayed ST-segment elevation is warranted. A standardized in-hospital serial ECG protocol should be considered to identify admitted patients who develop criteria for thrombolytic or other coronary revascularization therapy.     

Instability of ST segments in the early stages of acute myocardial infarction in patients undergoing continuous 12-lead ECG monitoring

Many patients presenting to the emergency department with suspected acute myocardial infarction (AMI) have an initial 12-lead electrocardiogram (ECG) nondiagnostic for acute injury and thus do not meet any accepted ECG criteria for thrombolytic therapy. Early studies in the use of intracoronary thrombolytic therapy documented that cyclic variations in ST segment magnitudes between normalcy and injury are common during the early phase of AMI and correspond to spontaneous intermittent coronary opening and reocclusion. The reliance on a single ECG to diagnose AMI may mean that many patients with AMI are missed if the initial ECG is obtained during a window of ST segment normalcy. We present 3 patients with AMI who underwent continuous 12-lead ST segment monitoring with frequent serial ECGs whose ST segments periodically normalized during the acute injury phase. We believe continuous 12-lead ST segment monitoring with frequent serial ECGs can aid the physician in identifying patients with AMI who may benefit from thrombolytic therapy and other urgent revascularization techniques.     

QT Dispersion Does Not Predict Early Ventricular Fibrillation After Acute Myocardial Infarction

Ventricular arrhythmias may be associated with increased QT dispersion (difference between maximum and minimum QT on standard 12-lead ECG). We performed a case control study to determine if QT dispersion on the admission ECG could predict early VF after acute myocardial infarction. The cases were 24 patients with acute myocardial infarction (14 inferior, 8 anterior, and 2 lateral) with VF within 12 hours of admission. There were 24 control patients without VF matched for site of infarction and ST segment score (sum of ST segment elevation). VF occurred a median of 153 minutes (interquartile range 93–245) after onset of chest pain and 33 minutes (range 7–104) after initial ECG. QT (399 ± 37 and 394 ± 37), QT corrected (440 ± 38 and 429 ± 29), and QT dispersion (68± 20 and 66 ± 27) were similar in patients and controls. By design, ST score was similar (11 ± 9 vs 9 ± 5 mV), although a good match could not be obtained for three patients with extreme ST elevation. Patients with VF presented to the hospital earlier after the onset of chest pain (median 95 min [range 65–188] compared to 150 min [range 80–270], P= 0.05) and had a lower serum sodium (138 ± 2.4 vs 140 ± 2.5, P = 0.05) than controls. Thus, QT interval and QT dispersion, measured on the presenting ECG, did not predict early VF after myocardial infarction.     

Identification of the culprit artery involved in inferior wall acute myocardial infarction using electrocardiographic criteria

We tested whether particular electrocardiogram (ECG) changes can identify the right coronary (RCA) or left circumflex (LCX) artery as the responsible vessel in inferior wall acute myocardial infarction (AMI) in 73 patients. A standard 12-lead ECG was performed within 6 h of onset of chest pain. Coronary angiography was performed between 1 week and 6 weeks after the infarction. RCA and LCX lesions were detected in 53 and 20 patients, respectively. The most useful ECG parameters for implicating the RCA were a higher ST elevation in lead III than lead II (specificity 94%, sensitivity 86%) and an S/R wave ratio > 0.33 plus ST segment depression > 1 mm in lead aVL (specificity 94%, sensitivity 92%). Absence of these criteria was associated with LCX occlusion (specificity 100%, sensitivity 87%). These results indicate that composite ECG criteria are useful in predicting the artery involved in inferior wall AMI.     

Complications from the use of thrombolytic agents in patients with cocaine associated chest pain

Previous investigators have noted that patients with cocaine associated chest pain frequently have abnormal electrocardiograms, including ST segment elevation, in the absence of ongoing myocardial ischemia. The effects of these nonischemic ST segment elevations have not been evaluated. We report two patients with cocaine associated chest pain and ST segment elevations who received thrombolytic agents in the absence of myocardial ischemia. Neither patient sustained a myocardial infarction, nor had clinical evidence of reperfusion. The ST segment elevations persisted after resolution of chest pain in both patients, and both of the patients experienced complications of thrombolytic therapy. One patient sustained a hemorrhagic stroke and one had minor oral-pharyngeal bleeding. Given the lack of documented efficacy, concerns about safety, and poor specificity of the electrocardiogram for myocardial ischemia in patients with cocaine associated chest pain, thrombolytic therapy should be used with caution in these patients.     

Thrombolytic therapy within one hour of the onset of acute myocardial infarction

Between 1986 and 1988, 239 consecutive patients with acute myocardial infarction received thrombolytic therapy up to 285 minutes after onset of symptoms; in 39 (17 with anterior infarction, 21 inferior, one lateral infarction) recombinant tissue plasminogen activator or anistreplase was administered a mean of 51 minutes (range 20-60 minutes) after the onset of symptoms. The patency rates (26 of 30; 87 per cent), rapid ST segment resolution (36 of 38; 95 per cent) and QRS score of less than or equal to 3 (28 of 38; 74 per cent) were statistically significantly higher for those seen and treated in the first hour in comparison with those seen and treated later. For those treated within the first hour mean peak creatine kinase was 1264 U/l for those with TIMI grade 2 or 3 (partial or complete perfusion) compared with 3005 U/l for those with TIMI grade 0 or 1 (no perfusion or penetration without perfusion) (p = 0.02): mean peak creatine kinase-MB for those with TIMI grade 2 or 3 perfusion was 115 U/l compared with 312 U/l for those with TIMI grade 0 or 1 (p = 0.01). Four of the 39 patients developed ventricular fibrillation following thrombolytic therapy, three within 24 hours of infarction and one following reinfarction on day 15. There were no significant bleeding complications. One patient died. Thrombolytic therapy within 1 hour of the onset of symptoms led to a very high angiographic patency rate, rapid ST segment resolution with preservation of left ventricular function. This therapy is without significant complications.     

Posterior myocardial infarction with isolated ST elevations in V8 and V9: Is this an "ST elevation MI"?

We report a case of a 53-year-old man whose first manifestation of coronary artery disease was an acute isolated posterior myocardial infarction (IPMI). Acute IPMI is relatively uncommon and predominantly due to occlusion of the left circumflex coronary artery. IPMI is challenging to diagnose due to the absence of ST segment elevation on a standard 12-lead electrocardiogram (ECG) even in the setting of total coronary artery occlusion and transmural (Q-wave) infarct. We discuss the diagnostic implications of the absence of tall R waves in leads V1 and V2 on this patient's ECG. The utility of posterior leads (V7 through V9) is demonstrated. The controversy surrounding the use of thrombolytic therapy or primary angioplasty in the setting of acute IPMI without ST segment elevation on a standard 12-lead ECG is reviewed.     

Using the 12-lead ECG to assess acute coronary patients

Acute coronary syndromes (ACS) are characterized by the rupture of unstable plaque within coronary arteries. Depending on the extent of the ensuing occlusion and myocardial damage, ACS can be classified as unstable angina, non-ST elevation myocardial infarction (MI) and ST elevation MI. The electrocardiogram (ECG) is an invaluable tool in the assessment of patients with ACS. It provides evidence for the location of myocardial ischaemia, injury and infarction and is a crucial factor in the decision to administer thrombolytic agents and other management strategies. The 12-lead ECG is limited to a view of the left ventricle, however it can be extended to provide additional information about the right ventricular and posterior walls. Critical care nurses with ECG skills can contribute to the early detection and management of patients with ACS.     

Anticoagulant and thrombolytic agents in acute coronary syndrome

The term acute coronary syndrome (ACS) pertains to the instable and life-threatening forms of a clinically manifest coronary artery disease with biochemical and/or electrocardiographic evidence od myocyte cell death. In detail, it includes the unstable angina pectoris, the non-ST segment elevation myocardial infarction (NSTEMI) the ST segment elevation myocardial infarction (STEMI) and as well the sudden cardiac death. As early reperfusion of ischaemic myocardium is the most effective way for limiting infarct size by restoring the balance between myocardial oxygen supply and demand, it is the most important therapeutic goal to achieve early and complete antegrade flow in the occluded or restricted vessel, related with a reduction of short and longtime complications as heart failure and severe arrhythmias. It is generally accepted, that the primary percutaneous coronary intervention (PCI) is the method of choice in acute myocardial infarction (STEMI) to restore TIMI-3 blood flow in occluded coronary arteries, if this can be performed within two hours of symptom onset and by a highly specialized team. Since this requirements are only met in 20% of hospitals caring for patients with STEMI in Germany, the therapy with thrombolytic and anticoagulant agents plays still an important role. Apart from a rapid and effective prehospital primary care, it depends furthermore on a differentiated anticoagulatory and antithrombotic therapy during coronary intervention to get optimal results.     

A potential diagnostic pitfall in acute chest pain: Massive pulmonary embolism mimicking acute STEMI

Background

Pulmonary embolism (PE) represents a clinical challenge for clinicians because of nonspecific presentations, including dyspnea, chest pain, and tachycardia. The immediate 12-lead electrocardiogram (ECG) is commonly used to facilitate differential diagnosis of acute chest pain. Although relative rare, massive pulmonary embolism could induce ST segment elevation and mimic acute myocardial infarction.

Initial experience with the Endicor X-sizer thrombectomy device in patients with ST segment elevation myocardial infarction

Summary We investigated 16 patients with ST segment elevation myocardial infarction who had an occluded coronary artery (TIMI 0) at initial angiogram. Instead of balloon angioplasty and stenting, patients were subjected to thrombectomy (Endicor X-sizer) and stenting. In 15/16 patients the occlusion could be crossed by the thrombectomy device resulting in TIMI flow 3 in all of them. Thereafter, stenting was performed. At final angiogram all 15 patients continued to show TIMI flow grade 3. Twelve-lead ECG was performed prior to and post-intervention. ST elevation was measured as the sum of eight leads for anterior infarction and of five leads for inferior infarction. In 13/15 patients, ECG analysis was possible (2 developed bundle branch block post-intervention). In all 13 patients, a >50% ST decrease of the initial amount of ST elevation was observed reaching a >70% reduction in 11 patients. Procedural complications were low (one coronary dissection after thrombectomy) and 30 days follow-up was uneventful. Thrombectomy using the Endicor X-Sizer device may become an attractive mechanical reperfusion strategy for patients with acute myocardial infarction. Received: 29 September 2001 Accepted: 5 December 2001     

Stress testing before discharge is not required for patients with low and intermediate risk of acute coronary syndrome after emergency department short stay assessment

Objective: To investigate the usefulness of stress testing before discharge in patients assessed low to intermediate risk of acute coronary syndrome (ACS). Methods: A prospective observational study was undertaken of patients presenting to the ED with suspected myocardial ischaemia. After negative initial electrocardiogram (ECG) and serum troponin testing, patients were admitted to the emergency short stay unit (ESSU) for further evaluation using a chest pain protocol that included stress testing as the final risk stratification tool. The primary outcome measure was evidence of myocardial ischaemia at stress testing. Results: Of the 300 patients enrolled and followed up, there were no deaths at 30 days and no myocardial infarcts in patients discharged from the short stay. Two patients (0.67%) had positive serum troponin levels at 6 h after the onset of chest pain and were diagnosed with non‐ST segment elevation myocardial infarctions. Three patients (1%) had abnormal stress testing and were admitted to hospital from ESSU. On review, all three patients were high risk, according to The National Heart Foundation of Australia/Cardiac Society of Australia and New Zealand guidelines. Conclusion: The present study showed that an ED short stay unit can effectively evaluate and manage patients with low and intermediate risk of ACS. The study suggests that patients with low and intermediate risk for ACS might safely be discharged after normal serial ECG and cardiac biomarkers, with a view to early outpatient stress testing. With strict adherence to admission criteria, there does not appear to be any benefit of stress testing before discharge.     

急诊经皮冠状动脉介入治疗ST段抬高心肌梗死的护理

目的研究ST段抬高心肌梗死急诊经皮冠状动脉介入治疗(急诊PCI)的护理要点。方法43例ST段抬高急性心肌梗死行急诊PCI术,观察胸痛、血压、心率、心律失常、再灌注心律失常、出血并发症,密切配合医生做好术前准备,术中监护和术后护理。结果25例术中出现再灌注心律失常,3例出现穿刺部位血肿,所有43例顺利出院。结论快速的术前准备,术中密切监测症状、心电图和血流动力学改变,术后及时发现并发症,做好心理护理与健康指导,有助于手术的安全和成功率。     

Acute myopericarditis with focal ECG findings mimicking acute myocardial infarction

Background: Although history, physical examination, laboratory data points, and electrocardiogram (ECG) are helpful, distinguishing among pericarditis, myopericarditis, and myocardial infarction can be difficult. Objectives: This case, which presents as pericarditis with concomitant myocarditis (myopericarditis), illustrates the four evolving ECG stages of pericarditis and highlights some of the potential difficulties in differentiating between myopericarditis and acute myocardial infarction. Case Report: We present the case of a previously healthy 15-year-old boy who presented to the Emergency Department (ED) from his family physician's office for chest pain and presumed pericarditis. The patient's initial ECG showed infero-lateral ST-segment elevation, and his troponin T was elevated at 1.54 ng/mL (ref. < 0.03). Several hours after presentation to the ED, the patient experienced “10/10” chest pain, and a repeat ECG showed ST elevation increased from the prior ECG. After an emergent echocardiogram revealed no regional wall abnormalities, he was transferred to a pediatric cardiac intensive care unit, where a heart catheterization revealed no coronary irregularities. He was discharged 4 days later with the diagnosis of myopericarditis. Conclusion: This case report illustrates some of the difficulties in differentiating among myopericarditis and myocardial infarction in a 15-year-old patient presenting with chest pain.     

经剑突结扎羊左冠状动脉致急性心肌梗死动物模型血流动力学的变化

目的 观察羊急性心肌梗死动物模型建立中血流动力学的变化.方法 用剑突结扎法制备羊急性心肌梗死动物模型.观察心肌梗死前及梗死后即刻、30 min、1 h和2 h心电图（ECG）ST段、平均动脉压（MAP）、中心静脉压（CVP）以及心率的变化.结果 术前描记ECG均正常.心肌梗死后即刻有8只、30 min有10只、2 h有18只羊可见ST段抬高;2只羊术中死亡.术后4周18只羊ECG描记均可见胸导联有病理性Q波;MAP、CVP和心率变化较心肌梗死前差异均无显著性（P均〉0.05）;有6只羊出现频发室性期前收缩,均经静脉注射利多卡因后消除.结论 羊小范围心肌梗死动物模型建立对循环功能影响轻微,形成梗死可靠,术后动物可长期存活,为临床冠心病的实验研究提供了一个有价值的动物模型.     

Consideration for primary angioplasty: impact on the door-to-drug time in AMI patients ultimately treated with thrombolytic agent

The objective of this study was to determine if consideration for percutaneous transluminal coronary angioplasty (PTCA) delays administration of thrombolytic therapy in acute myocardial infarction (AMI) patients. Retrospective medical record review of patients ultimately diagnosed with AMI who presented to the ED with chest pain and ST segment elevation on the electrocardiogram; these patients also received acute reperfusion therapy (PTCA or thrombolytic agent). AMI was diagnosed by abnormal elevations in the creatinine phosphokinase MB fraction. The study period covered 2 years (July 1, 1994 to June 30, 1996) in a university hospital ED with an annual volume of 60,000 patient-visits. The use of reperfusion therapies, time intervals, and times of presentation were recorded. Patients were divided into two groups based on cardiac catheterization laboratory (CATH) availability: (group I, CATH currently in operation, Monday to Friday, 7 am to 7 pm and group II, CATH currently not in-operation, all other times). Fifty-two patients with AMI met entry criteria. Patients were treated with thrombolytic therapy in 25 cases; PTCA in 27 cases. Patients received thrombolytic agents within statistically equivalent time intervals regardless of the period of presentation; time to thrombolytic therapy for group I patients was 38 +/- 16 minutes compared with 36 +/- 26 minutes for group II patients (P =. 891). A trend toward significance was noted in the use of PTCA compared with thrombolytic agent; Group I patients were more often treated with PTCA (19) compared with group II patients (11, P =.067). Patients were more rapidly treated with PTCA during CATH operation; the mean time to PTCA for group I patients was 73.5 minutes compared with PTCA for group II patients with 107.8 minutes (P =.033). The consideration for PTCA did not significantly delay the administration of thrombolytic therapy at the study site institution. PTCA was initiated more rapidly in patients presenting with AMI during hours of CATH operation.     

非ST段抬高型急性冠状动脉综合征患者胸痛时间、肌钙蛋白水平及心电图ST段下移的诊断价值

目的:探讨非ST段抬高型急性冠状动脉综合征(ACS)患者胸痛时间、肌钙蛋白水平及心电图ST段下移的临床诊断价值。方法:收集自2008-06—2008-12,在急诊科因急性胸痛拟诊不稳定性心绞痛(UA)及非ST段抬高心肌梗死(NSTEMI)收入院且记录资料完整的54例患者。仔细询问病史、体检,据胸痛持续时间分成3组(0.5h,0.5～2h,≥2h),并完成常规18导联心电图检查,将患者入院时心电图ST段下移幅度分成3组(1mV,1～2mV,≥2mV),同时抽静脉血做肌钙蛋白I(TnI)检测。据TnI水平将患者分成3组(TnI0.02μg/L,0.02μg/L～0.04μg/L,≥0.04μg/L),根据冠状动脉造影结果诊断急性心肌梗死。结果:随着胸痛发生时间延长或肌钙蛋白水平升高,心肌梗死的发病率显著升高。随着ST段下移幅度加深,心肌梗死的发病率没有升高。结论:胸痛时间及TnI水平对非ST段抬高的ACS患者的预测均有重要价值,但心电图的ST段变化对于非ST段抬高的ACS患者的预测价值有待进一步探讨。     

胸痛中心持续改进机制对急性心肌梗死患者行PPCI治疗的影响

目的 探讨胸痛中心持续改进机制对急性ST 段抬高型心肌梗死（STEMI）行直接经皮冠状动脉介入治疗 （PPCI）患者关键指标的影响。方法 2017年12月至2018年11月在我院行PPCI的急性 STEMI 患者90例，其中2017年12月至2018年5月46例为对照组，2018年6月至 2018年11月44例为观察组。比较两组的首份心电图获取时间、微信传输比例、绕行急诊和冠心病重症监护病房（CCU）比例、门球扩张（D to B）时间。结果 观察组首份心电图获取时间、D to B时间低于对照组（P<0.05）；观察组微信传输比例、绕行急诊和CCU比例高于对照组（P<0.05）。结论 胸痛中心持续改进可提高STEMI患者的微信传输比例、绕行急诊和CCU比例，缩短首份心电图获取时间、D to B时间，为STEMI患者进一步救治赢得时间。     

急性下壁心肌梗死患者的临床特点分析

目的 分析研究急性下壁心肌梗死患者的临床特点. 方法 将急性下壁心肌梗死患者100例根据冠状动脉造影结果分为两组:76例为右冠状动脉(RCA)闭塞(A组),24例为左回旋支冠状动脉(LCX)闭塞(B组). 结果 心电图ST段抬高STⅢ>STⅡ及ST段压低STAVL>ST I A组显著高于B组(均P<0.05);ST段抬高STⅢ0.1 mV A组显著高于B组(P<0.05);胸前导联V1～6ST段压低患者中,合并左前降支冠状动脉(LAD)病变的患者显著高于胸前导联V1～6ST段无压低者(P<0.05);左心室射血分数(LVEF)A组[(51±14)%]显著低于B组[(57±10)%](P<0.05);合并右心室心肌梗死A组显著高于B组(P<0.05);急性下壁心肌梗死患者总的住院病死率6%,均为A组,但心源性休克、心力衰竭、Ⅱ、Ⅲ度房室传导阻滞,室性心动过速/心室颤动及住院病死率,两组差异均无统计学意义(均P>0.05);死亡者中心源性休克占83.3%. 结论 心电图Ⅲ、Ⅱ、I、AVL、及V4R导联ST段变化能预测急性下壁心肌梗死相关血管,急性下壁心肌梗死患者伴胸前导联ST段压低提示LAD病变,RCA闭塞所致下壁心肌梗死LVEF低于LCX闭塞者,心源性休克为死亡主要原因.     

急性下壁心肌梗死胸前导联ST段压低的临床意义

目的分析急性下壁心肌梗死伴胸前导联ST段压低的临床意义。方法选择84例急性下壁心肌梗死患者常规心电图及24h动态心电图进行对照分析。结果急性下壁心肌梗死伴胸前导联ST段压低多于不伴胸前导联ST段压低（P〈0．01）;下壁伴正后壁心肌梗死伴胸前导联ST段压低多于不伴胸前导联ST段压低（P〈0．01）;下壁伴右心室心肌梗死与胸前导联ST段压低无明显关联（P〈0．01）;急性下壁心肌梗死伴胸前导联ST段压低者严重室性心律失常与房室传导阻滞的发生率较不伴胸前导联ST段压低者高（P〈0．01）。结论急性下壁心肌梗死伴胸前导联ST段压低往往提示梗死范围大或同时存在心肌缺血、冠脉病变广泛、心功能损害较严重,并且严重室性心律失常与房室传导阻滞的发生率明显增高,心肌酶峰值明显增高临床预后较差。