Francis M. Fesmire

Delta CK-MB outperforms delta troponin I at 2 hours during the ED rule out of acute myocardial infarction.

It has been shown that a rise in creatine kinase MB bank (CK-MB) of > or = + 1.6 ng/mL in 2 hours is more sensitive and equally specific for detection of acute myocardial infarction (AMI) as compared with a 2-hour CK-MB > or = 6 ng/mL during the emergency department (ED) evaluation of chest pain. Because cardiac specific troponin I (cTnI) is thought to have similar early release kinetics as compared with CK-MB mass, we undertook a retrospective cohort study in 578 chest pain patients whose baseline CK-MB and cTnI was less than two times the hospitals upper limits of normal and who underwent a 2-hour CK-MB and cTnI to compare sensitivities and specificities of the 2-hour delta CK-MB (deltaCK-MB) and delta cTnI (delta cTnI) for AMI and 30-day Adverse Outcome (AO). Thirty day AO was defined as AMI, life-threatening complication, death, or percutaneous transluminal coronary angioplasty (PTCA)/coronary artery bypass graft (CABG) within 30 days of ED presentation. Optimum delta values were determined by choosing the smallest cutoff value greater than the assay precision where the deltaCK-MB and delta cTnI had a positive likelihood ratio for 30-day AO of > or = 15. A deltaCK-MB > or = +1.5 ng/mL was more sensitive than a deltaTnI > or = +0.2 ng/mL for AMI (87.7% versus 61.4%; P < .0005) and 30-day AO (56.7% versus 42.3%; P < .005). There were no differences in specificities for AMI and 30-day AO. Combining the two tests (MBdelta > or = +1.5 ng/mL and/or a deltaTnI > or = +0.2 ng/mL) resulted in an incremental increase in sensitivity of 89.5% for AMI and 61.9% for AO (P < .005). Patients with either a rise in CK-MB of > or = +1.5 ng/mL or rise in cTnI of > or = +0.2 ng/mL in 2 hours should receive consideration for aggressive antiischemic therapy and further diagnostic testing before making an exclusionary diagnosis of nonischemic chest pain.

Continuous 12-lead electrocardiograph monitoring in the emergency department

Many patients presenting to the emergency department with suspected acute myocardial infarction have an initial electrocardiogram (ECG) non-diagnostic for acute injury or ischemia. Continuous ST segment monitoring devices have been used by physicians in the past to diagnose ischemia in the ambulatory outpatient population and to identify coronary occlusion in postthrombolytic and postsurgical patients. We report three patients with suspected acute myocardial infarction who underwent real-time continuous 12-lead ST segment monitoring with frequent serial ECGs on a microprocessor-controlled device during their initial emergency department evaluation. Continuous 12-lead ECG monitoring revealed significant changes on the ECG in all three cases presented, with a resultant change in emergency department therapy. Interestingly, all of these patients had significant ECG changes in the absence of recurrence of chest pain. We believe real-time continuous 12-lead ST segment monitoring with frequent serial ECGs can identify patients with an initially nondiagnostic or atypical ECG who may benefit from early interventional 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.

Improved identification of acute coronary syndromes with second generation cardiac troponin I assay: utility of 2-hour delta cTnI ≥+0.02 ng/mL

It has been shown that the 2-h Stratus II delta creatine kinase-MB (CK-MB) is more sensitive and is equally specific compared to a 2-h Stratus II CK-MB and to a 2-h Stratus II delta cardiac troponin-I (DeltacTnI) for identification of acute myocardial infarction and adverse outcome (AO). Because the newest generation of Stratus (Stratus CS) cTnI assay has an analytical sensitivity of 0.03 ng/mL, compared to 0.35 ng/mL for the first generation assay, we undertook a small pilot study of 120 chest pain patients to compare sensitivities and specificities for 30-day AO of the Stratus CS DeltacTnI immunoassay to the DeltaCK-MB and DeltacTnI, as measured by the Abbott Axsym immunoassay, and to the DeltaCK-MB, as measured by the Stratus CS. A Stratus CS DeltacTnI > or = +0.02 ng/mL in 2 h was more sensitive (61.9%) than an Axsym DeltaCK-MB > or = +1.3 ng/mL (38.1%; p = 0.03), a Stratus CS DeltaCK-MB > or = +0.4 ng/mL (38.1%; p = 0.03), and an Axsym DeltacTnI > or = +0.3 ng/mL (33.3%; p = 0.03) for 30-day AO. There were no differences in specificities. Our data support enhanced identification of ACS with a second generation cTnI assay. Pending larger studies, patients with a rise in DeltacTnI of > or = +0.02 ng/mL in 2 h, as measured by the Stratus CS immunoassay, should receive consideration for aggressive anti-ischemic therapy and further diagnostic testing prior to making an exclusionary diagnosis of non-ischemic chest pain.

ST-segment instability preceding simultaneous cardiac arrest and AMI in a patient undergoing continuous 12-lead ECG monitoring

Little data exist concerning the actual onset time (time zero) in sudden death (SD) and acute myocardial infarction (AMI). Most studies have focused on describing the warning arrhythmias that occur before SD and AMI and have relied on retrospective analyses of fortuitous data obtained from patients who experience these adverse outcomes while undergoing routine ambulatory holter monitoring. Because of the limitations of holter monitoring, little information is known concerning the actual incidence of ST-segment changes preceding SD and AMI. The first case of simultaneous onset of silent SD and AMI occurring in a patient undergoing continuous 12-lead electrocardiograph (ECG) monitoring during his initial emergency department evaluation is reported. Analyses of the serial 12-lead electrocardiographs showed extensive transient silent ST-segment elevations and depressions preceding cardiac arrest and AMI and provided insight in the pathogenesis of SD and AMI. Continuous 12-lead ECG monitoring can identify patients at high risk for SD and AMI and allow physicians to intervene before the development of life-threatening conditions.

Early use of glycoprotein IIb/IIIa inhibitors in the ED treatment of non-ST-segment elevation acute coronary syndromes: a local quality improvement initiative.

A prospective observational study was conducted in 2,007 patients experiencing chest pain to determine impact of local quality improvement (QI) measures on the use of glycoprotein (GP) IIb/IIIa inhibitors in the ED treatment of high-risk patients with non-ST-segment elevation acute coronary syndromes (ACS). Patients with injury on the initial ECG or new sustained injury on continuous ECG were excluded. QI interventions were as follows: control (0-4 mo): no interventions (standardized protocols and prewritten orders in place 4 months prior); phase I (5-8 mo): simple education/awareness program with posted drug information pamphlets and eligibility criteria; phase II (9-12 mo): mandated QI form with real-time feedback and focused one-on-one physician education championed by an ED physician QI advocate. A total of 179 (8.9%) of the study patients met predefined high-risk criteria. Of these, a total of 41 (23.0%) patients had GP IIb/IIIa inhibitor therapy initiated in the ED. Percent of high-risk patients receiving therapy increased from 6.0% during the control phase to 16.1% during phase I and 50.9% during phase II. After controlling for patient demographics, patients treated during phase I had a 2.8 times increased odds (95% confidence interval CI: 0.8-10.3; P =.11 [not significant]) of receiving GP IIb/IIIa inhibitor relative to the control phase, and patients treated during phase II had a 20.2 times increased odds (95% CI: 6.1-66.9; P <.0001) of treatment. In conclusion, local QI measures incorporating standardized protocols, preprinted orders, physician education, and interactive feedback championed by an ED QI physician advocate can increase early use of GP IIb/IIIa inhibitors in the ED treatment of high-risk patients presenting with chest pain.

Improved identification of acute coronary syndromes with delta cardiac serum marker measurements during the emergency department evaluation of chest pain patients

Current findings from the American College of Emergency Physicians (ACEP) are that no serum marker reliably identifies or excludes acute myocardial infarction (AMI) within 6 h of symptom onset. The ACEP recommends repeat serum marker testing 6–10 h after symptom onset for CK-MB mass and subform, and 8–12 h after symptom onset for cardiac troponin I and T before making an exclusionary diagnosis of non-AMI chest pain. A new approach for identifying myocardial necrosis is to rely on time changes in the serum marker value over an abbreviated time interval (slope or delta values) as opposed to the traditional approach of relying on a value exceeding the threshold of normalcy. As assays become ever more sensitive and precise, this approach has the potential for both reliably identifying and excluding AMI (and subsets of high-risk unstable angina) at earlier time intervals with no loss in specificity. This article discusses some of the experimental evidence for this delta approach and some preliminary evidence for the potential of utilizing second-generation cTnl assays for the identification of acute coronary syndromes. Finally, we discuss a unique way of viewing receiver-operating characteristic (ROC) curves as catalogs of likelihood ratios, which we believe will be more useful to the clinician in the proper interpretation of serum marker values.

Cardiac Injury Due to Accidental Discharge of Nail Gun

BACKGROUND Since 1991, the incidence of injuries associated with pneumatic and explosive powered nail guns has steadily been rising due to increasing use of these devices by the untrained consumer. The vast majority of injuries involve the extremities, but injuries have been reported to occur in virtually every area of the body. OBJECTIVE Discuss the epidemiology, pathophysiology, and management of penetrating cardiac nail gun injuries. CASE REPORT A 33-year-old man sustained a penetrating cardiac injury from accidental discharge of a nail gun. The patient had successful repair of a laceration to his right ventricle. CONCLUSIONS Penetrating cardiac injuries from pneumatic nail guns are rare and have mortality similar to stab wounds. Improved safety mechanisms and training are the keys to prevention. Consideration also should be given to implementing legislation restricting the sale of nail guns.

Use of Neural Networks to Predict Adverse Outcomes from Acute Coronary Syndrome for Male and Female Patients

Neural networks have been used to examine a set of thirteen objective features and a single subjective physicians assessment for emergency room patients with symptoms possibly indicative of acute coronary syndrome (ACS). The objective data is information routinely collected during triage. The neural networks were used to fuse the disparate types of information with the goal of forecasting thirty-day adverse patient outcome. Results were evaluated using receiver operating characteristic curves describing the outcomes of the nets, both using only objective features and including the subjective physicians assessment. These results, based on all patient data, are compared to those obtained using neural networks trained on information from male and female patients separately. While preliminary, the results of this continuing study are significant from the perspective of potential use of the intelligent fusion of biomedical informatics to aid the physician in prescribing treatment necessary to prevent serious adverse outcome from ACS.

The ECG in acute myocardial infarction

The initial ECG is the most rapid and readily available tool in the emergency department for the evaluation of patients presenting with suspected myocardial infarction. However, studies have shown that the initial ECG is diagnostic of acute myocardial infarction in only a minority of patients. This paper discusses the importance of the initial ECG and other information in aiding the disposition of patients with suspected myocardial infarction. Classic electrocardiographic descriptions are discussed as well as the newer terminology of Q wave versus non-Q wave infarction and ST segment versus T wave infarction. A brief review is made of the electrophysiology of the ECG changes seen in myocardial infarction. Finally, clinical studies are presented that establish a definite role for the use of the initial ECG.