Continuous 12-lead electrocardiographic monitoring in an emergency department chest pain unit: an assessment of potential clinical effect

STUDY OBJECTIVES: Continuous 12-lead serial ECG monitoring has been proposed to assist in the evaluation of patients with acute coronary syndrome and nondiagnostic ECG in an emergency department chest pain unit. However, the ability of serial ECG to detect acute coronary syndrome and its benefit in addition to a standard protocol has not been established. We evaluate the ability of continuous 12-lead ECG to detect acute coronary syndrome, assess the incremental benefit of the serial ECG in association with a set protocol in an ED chest pain unit, and evaluate whether serial ECG changes could be considered as prognostic factors. METHODS: Patients who met Agency for Health Care Policy and Research guidelines for intermediate risk for short-term cardiovascular event unstable angina were prospectively studied in the chest pain unit. Patients were monitored with the Mortara Instruments ELI 100 STM continuous 12-lead ECG system with ST-segment analysis. ST-segment changes of greater than 100 microV in 2 or more contiguous leads or greater than 200 microV in 1 lead were considered positive. Data were compared with serial serum cardiac markers, cardiac function study results, angiographic results, and 30-day outcome results. RESULTS: One hundred nineteen patients had serial ECG applied. The median duration of monitoring was 4.2 hours. Forty patients were given a diagnosis of acute coronary syndrome. Chest pain unit protocol detected 52 patients, and 23 were given a diagnosis of acute coronary syndrome (sensitivity 58%; specificity 63%). Sixteen patients had ST-segment changes of greater than 100 microV or greater than 200 microV, and 9 were given a diagnosis of acute coronary syndrome. The addition of the serial ECG to the chest pain unit protocol increased the sensitivity to 65% and decreased the specificity to 58%. Two patients with ST-segment changes but none without ST-segment changes had an adverse cardiac event, yielding a sensitivity of 100% and a specificity of 88%. CONCLUSION: Serial ECG is of limited value in the diagnostic evaluation of intermediate-risk patients managed in the chest pain unit with a standard protocol. However, when ST-segment changes are present, they indicate an increased likelihood for an adverse cardiac event.     

Continuous 12-lead ST-segment monitoring improves identification of low-risk patients with chest pain and a worse in-hospital outcome

BACKGROUND: Various strategies have been proposed to improve diagnosis and triage of patients with chest pain at low risk, but uncertainty still exists on the optimal combination of diagnostic tools that should be used in this subset of patients. HYPOTHESIS: The aim of this study was to evaluate the incremental benefit of continuous 12-lead ST-segment monitoring over that provided by conventional diagnostic tools in patients with chest pain. METHODS: Of 232 consecutive patients referred because of chest pain, 52 were classified as low-risk according to the Agency for Health Care Policy and Research unstable angina guidelines and observed for 12 h with serial cardiac enzymes and electrocardiograms (ECG) (every 3 h). All patients also underwent both echocardiography at entry and continuous 12-lead ST-segment monitoring during the observation period. RESULTS: During a mean hospital stay of 3.7 days (range 1-14 days), a benign outcome was observed in 37 patients (71%), whereas 15 patients (29%) had major cardiac events or recurrence of chest pain of ischemic origin. Addition of ST-segment monitoring findings to baseline clinical data as well as to serial enzymes and ECG features added significant incremental prognostic value (p < 0.001). Multivariate analysis showed reproduction of pain by chest pressure (p < 0.05) and presence of ST-segment changes (> or = 0.1 mV) during 12-lead ST-segment monitoring (p < 0.001) as independent predictors of a benign or unfavorable outcome. CONCLUSIONS: In low-risk patients with chest pain, continuous 12-lead ST-segment monitoring provides significant incremental diagnostic and prognostic information to currently used clinical, enzymatic, and ECG data, and is helpful in identifying the subset of patients with a worse in-hospital outcome.     

Identification of the optimal electrocardiographic leads for detecting acute epicardial injury in acute myocardial infarction

Current coronary care electrocardiographic (ECG) monitoring techniques are aimed at detection of cardiac arrhythmias rather than myocardial ischemia. However, in patients with acute myocardial infarction (AMI) who undergo reperfusion therapy, monitoring ST-segment deviation could provide an early noninvasive indicator of coronary artery reocclusion. In this study, the admission 12-lead ECGs of patients with initial AMI were used to propose optimal lead locations for ST-segment monitoring. The study population was selected from consecutive Duke University Medical Center admissions during 1965 to 1981 who met the following inclusion criteria: chest pain for no more than 8 hours, initial AMI documented by ECG and 3 of 4 enzyme criteria, greater than or equal to 0.1 mV (1 mV = 10 mm) of ST elevation in at least 1 of the standard 12 leads (not aVR) on admission ECG, and no ECG evidence of conduction disturbances, ventricular hypertrophy or tachycardia. ST-segment deviation was quantified; AMI location was assigned based on the lead with maximal deviation. Of the 80 patients who had an inferior AMI, lead III was both the most frequent location for ST elevation (94%) and the most common site with maximal ST deviation. Lead V2 had the highest incidence of ST-segment depression (60%). In the 68 patients who had an anterior AMI, lead V2 had the highest frequency of ST elevation (99%). Leads V2 and V3 were the most common sites of maximal elevation. Thus, for monitoring ST deviation, leads III and V2 may be superior to leads II and V1, which are commonly used in arrhythmia monitoring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Accuracy of 22-lead ECG analysis for diagnosis of acute myocardial infarction and coronary artery disease in the emergency department: a comparison with 12-lead ECG.

STUDY OBJECTIVES: To compare a new 22-lead ECG with the 12-lead ECG for diagnosis of acute myocardial infarction (AMI). DESIGN: Prospective study of all consenting patients presenting to the emergency department with chest pain. SETTING: Urban hospital ED. TYPE OF PARTICIPANTS: 163 patients admitted with a cardiac-related diagnosis and complete data sets of 22- and 12-lead ECG results and creatine kinase-MB analysis. INTERVENTIONS: Patient care and existing protocols were unaltered, with the exception of including the new 22-lead ECG. MEASUREMENTS AND MAIN RESULTS: Forty-one of 163 patients had an AMI as defined by creatine kinase-MB analysis. The 22-lead ECG provided a statistically significant improvement in sensitivity (83%) for AMI diagnosis over the 12-lead ECG (51%) with specificities of 76% and 99%, respectively. CONCLUSION: When combined with clinical judgment, the 22-lead ECG could provide a 97.6% sensitivity for AMI diagnosis while reducing unnecessary admissions for "rule-out MI" by 69%.     

The combination of a continuous 12-lead ECG and troponin T; a valuable tool for risk stratification during the first 6 hours in patients with chest pain and a non-diagnostic ECG.

AIMS: The aim was to examine the early prognostic value of a combination of a continuous 12-lead ECG and troponin T in patients with chest pain and an ECG non-diagnostic for acute myocardial infarction. METHODS AND RESULTS: ST monitoring was performed and samples for analysis of troponin T were collected from admission for 12 h from 598 patients. After 6 h, the peak value of troponin T in 27% was > or = 0.10 microg.l(- 1), while 15% had had ST episodes, defined as transient ST deviations of at least 0.1 mV. Both a troponin T > or = 0.10 microg. l(-1) and ST episodes predicted worsening outcome. After 30 days, there were 6.8% and 1.4% (P<0.01) cardiac deaths or myocardial infarctions in the group with and without troponin T > or = 0.10 microg.l(-1), respectively. The corresponding event rates in patients with and without ST episodes were 10% and 1.6% (P<0.001). In a multivariate analysis both troponin T and ST episodes were independent predictors of cardiac death or myocardial infarction. When ST monitoring and troponin T status were combined, patients could be divided into low-, intermediate-, and high-risk groups. CONCLUSIONS: A combination of continuous 12-lead monitoring and troponin T seems to be a valuable tool for risk stratification during the first 6 h in this population.     

ST-segment deviation analysis of the admission 12-lead electrocardiogram as an aid to early diagnosis of acute myocardial infarction with a cardiac magnetic resonance imaging gold standard.

OBJECTIVES: The purpose of this study was to validate existing 12-lead electrocardiographic (ECG) ST-segment elevation myocardial infarction (STEMI) criteria in the diagnosis of acute myocardial infarction (AMI) and the application of similar ST-segment depression (STEMI-equivalent) criteria with contrast-enhanced cardiac magnetic resonance imaging (ceMRI) as the diagnostic gold standard. BACKGROUND: The admission ECG is the cornerstone in the diagnosis of AMI, and ceMRI is a new diagnostic gold standard that can be used to validate existing and novel 12-lead ECG criteria. METHODS: One hundred fifty-one consecutive patients with their first hospital admission for chest pain underwent ceMRI. The 116 patients without ECG confounding factors were included in this study, and AMI was confirmed in 58 (50%). The admission ECG was evaluated on the basis of the lead distribution of ST-segment deviation according to current American College of Cardiology/European Society of Cardiology (ACC/ESC) guidelines. RESULTS: A sensitivity of 50% and specificity of 97% for AMI were achieved with the currently applied ST-segment elevation criteria. Consideration of ST-segment depression in addition to elevation increased sensitivity for detection of AMI from 50% to 84% (p < 0.0001) but only decreased specificity from 97% to 93% (p = 0.50). There were no significant differences in AMI location or size between patients meeting the 12-lead ACC/ESC ST-segment elevation criteria and those only meeting the ST-segment depression criteria. CONCLUSIONS: In patients admitted to hospital with possible AMI, the consideration of both ST-segment elevation and depression in the standard 12 lead-ECG recording significantly increases the sensitivity for the detection of AMI with only a slight decrease in the specificity.     

Diagnostic testing of the emergency department patient with chest pain

In evaluating patients with nondiagnostic initial clinical or electrocardiogram (ECG) findings for acute cardiac ischemia, continuous 12-lead ECG monitoring increases the detection of diagnostic ECG findings, including ST-segment elevation, in patients awaiting hospital admission. Rest scanning with technitium-99m sestamibi is able to risk stratify low-moderate risk patients into lower and higher risk groups for cardiac events. Caveats include the reduced sensitivity of scanning of patients who are pain free and the need for follow-up exercise scans for patients free of perfusion defects at rest. Cardiac markers, particularly the troponins, show great promise for the detection of a larger part of the spectrum of acute coronary syndromes in the emergency department, including patients with minimal myocardial damage and higher risk for short-term death and nonfatal acute myocardial infarction. Accelerated diagnostic protocols using serial testing with cardiac markers, ECGs and then provocative testing over a 14-hour period, are feasible, safe, and cost-effective.     

The Erlanger chest pain evaluation protocol: a one-year experience with serial 12-lead ECG monitoring,two-hour delta serum marker measurements,and selective nuclear stress testing to identify and exclude acute coronary syndromes

STUDY OBJECTIVE: We determine the overall use of a 6-step accelerated chest pain protocol to identify and exclude acute coronary syndrome (ACS) and to confirm previous findings of the use of serial 12-lead ECG monitoring (SECG) in conjunction with 2-hour delta serum marker measurements to identify and exclude acute myocardial infarction (AMI). METHODS: A prospective observational study was conducted over a 1-year period from January 1, 1999, through December 31, 1999, in 2,074 consecutive patients with chest pain who underwent our accelerated evaluation protocol, which includes 2-hour delta serum marker determinations in conjunction with automated SECG for the early identification and exclusion of AMI and selective nuclear stress testing for identification and exclusion of ACS. In patients not undergoing emergency reperfusion therapy, physician judgment was used to determine patient disposition at the completion of the 2-hour evaluation period: admit for ACS, discharge or admit for non-ACS condition, or immediate emergency department nuclear stress scan for possible ACS. A positive protocol was defined as a positive result in 1 or more of the 6 incremental steps in our chest pain evaluation protocol: (1) initial ECG diagnostic of acute injury or reciprocal injury; (2) baseline creatine kinase (CK)-MB level of 10 ng/mL or greater and index of 5% or greater or cardiac troponin I level of 2 ng/mL or greater; (3) new/evolving injury or new/evolving ischemia on SECG; (4) increase in CK-MB level of +1.5 ng/mL or greater or cardiac troponin I level of +0.2 ng/mL or greater in 2 hours; (5) clinical diagnosis of ACS despite a negative 2-hour evaluation; and (6) reversible perfusion defect on stress scan compared with on resting scan. All patients were followed up for 30-day ACS, which was defined as myocardial infarction (MI), percutaneous coronary intervention/coronary artery bypass grafting, coronary arteriography revealing stenosis of major coronary artery of 70% or greater not amenable to percutaneous coronary intervention/coronary artery bypass grafting, life-threatening complication, or cardiac death within 30 days of ED presentation. RESULTS: Discharge diagnosis in the 2,074 study patients consisted of 179 (8.6%) patients with AMI, 26 (1.3%) patients with recent AMI (decreasing curve of CK-MB), and 327 (15.8%) patients with 30-day ACS. At 2 hours, sensitivity and specificity for MI (AMI or recent AMI) of SECG plus delta serum marker measurements was 93.2% and 93.9%, respectively (positive likelihood ratio 15.3; negative likelihood ratio 0.07). At the completion of the full ED evaluation protocol (positive result in >or=1 of the 6 incremental steps), sensitivity and specificity for 30-day ACS was 99.1% and 87.4%, respectively (positive likelihood ratio 7.9; negative likelihood ratio 0.01). CONCLUSION: An accelerated chest pain evaluation strategy consisting of SECG, 2-hour delta serum marker measurements, and selective nuclear stress testing in conjunction with physician judgment identifies and excludes MI and 30-day ACS during the initial evaluation of patients with chest pain.     

Clinical Significance of Conditions Presenting with ECG Changes Mimicking Acute Myocardial Infarction

The electrocardiogram (ECG) is the primary tool in the diagnosis of acute myocardial infarction (AMI). However, other clinical conditions, both cardiac and noncardiac originated pathologies, may result in ECG tracing of AMI. This may lead to an incorrect diagnosis, exposing the patients to unnecessary tests and potentially harmful therapeutic procedures. The aim of this report is to increase the still insufficient awareness of clinicians from multiple disciplines, regarding the different clinical syndromes, both cardiac and noncardiac, associated with ECG abnormalities mimicking AMI, to avoid unjustified thrombolytic therapy or intervention procedures. During a 9-year period, the data from six patients (five females, one male; mean age, 50 years [range, 18 to 78 years]) who were admitted to cardiac care unit (CCU) with transient ECG changes resembling AMI were recorded retrospectively. During this 9-year period, 5,400 patients were hospitalized in CCU: 1,350 patients were diagnosed as ST-elevation myocardial infarction (STEMI) and 4,050 patients were diagnosed as non-ST-elevation myocardial infarction (NSTEMI). Only two out of six patients had chest pain with ECG changes criteria suspicious of AMI. STEMI was suspected in four out of six patients. All patients, but one, had normal left ventricular (LV) function. One patient had transient LV dysfunction. All patients, but one, with perimyocarditis, had normal serum cardiac markers. In four out of six patients, who underwent coronary arteries imaging during hospitalization (by angiography or by CT scan), normal coronary arteries were documented. Two patients who underwent ambulatory cardiac CT scan imaging after being discharged from hospital documented patent coronary arteries (case no. 3), or some insignificant irregularities (case no. 4). The discharge diagnoses from CCU were as follows: postictal syndrome, pericarditis, hypothermia, stress-induced (“tako-tsubo”) cardiomyopathy, anaphylactic reaction, and status of postchemotherapy. All patients experienced full recovery with normal ECG tracing. During the 5-year follow-up, all patients were alive, and cardiac morbidity was not reported. We conclude that both cardiac and noncardiac clinical syndromes may mimic AMI. Comprehensive clinical examination and profound medical history are crucial for making the correct diagnosis in conditions with ECG changes mimicking AMI.     

Continuous 12-lead electrocardiographic ST monitoring adds prognostic information to the thrombolysis in myocardial infarction risk score in patients with non-ST-elevation acute coronary syndromes

BACKGROUND: Continuous 12-lead electrocardiographic (ECG) ST monitoring and the Thrombolysis In Myocardial Infarction Risk Score (TIMI-RS), both have been shown to be useful for early risk stratification in patients with non-ST elevation acute coronary syndromes (NSTACS). HYPOTHESIS: Transient ST ischemic events, detected by continuous 12-lead ECG ST monitoring, early in the course of NSTACS, may add prognostic information to the TIMI-RS. METHODS: In all, 567 consecutive patients with a NSTACS underwent 24-h continuous 12-lead ECG ST monitoring. An ST ischemic event was defined as a transient ST shift in any lead of > or = 0.10 mV compared with the reference ECG, lasting for > or = 1 min. RESULTS: The incidence of the composite of death, nonfatal myocardial infarction (or reinfarction) and recurrent ischemia by Day 14 was 22.2%. By Day 30, the incidence of the composite of death and nonfatal myocardial infarction (or reinfarction) was 14.7%. There was a significantly increased risk of 14-day (p value for trend < 0.001) or 30-day (p value for trend <0.001) composite endpoint with increasing of TIMI-RS. Moreover, the occurrence of > or = 1 ST shifts during ST monitoring was associated with a significantly increased risk of 14- (p value < 0.001) or 30-day (p value < 0.001) composite endpoint, and this was true throughout the groups of TIMI-RS. CONCLUSIONS: The present study suggests that continuous 12-lead ECG ST monitoring, early in the course of NSTACS, may serve as an affordable tool to add prognostic information to the TIMI-RS.     

Acute myocardial infarction with isolated ST-segment elevation in posterior chest leads V7-9: "hidden" ST-segment elevations revealing acute posterior infarction.

OBJECTIVES: This study was done to determine whether electrocardiographic (ECG) isolated ST-segment elevation (ST) in posterior chest leads can establish the diagnosis of acute posterior infarction in patients with ischemic chest pain and to describe the clinical and echocardiographic characteristics of these patients. BACKGROUND: The absence of ST on the standard 12-lead ECG in many patients with acute posterior infarction hampers the early diagnosis of these infarcts and thus may result in inadequate triage and treatment. Although 4% of all acute myocardial infarction (AMI) patients reveal the presence of isolated ST in posterior chest leads, the significance of this finding has not yet been determined. METHODS: We studied 33 consecutive patients with ischemic chest pain suggestive of AMI without ST in the standard ECG who had isolated ST in posterior chest leads V7 through V9. All patients had echocardiographic imaging within 48 h of admission, and 20 patients underwent coronary angiography. RESULTS: Acute myocardial infarction was confirmed enzymatically in all patients and on discharge ECG pathologic Q-waves appeared in leads V7 through V9 in 75% of the patients. On echocardiography, posterior wall-motion abnormality was visible in 97% of the patients, and 69% had evidence of mitral regurgitation (MR), which was moderate or severe in one-third of the patients. Four patients (12%), all with significant MR, had heart failure, and one died from free-wall rupture. The circumflex coronary artery was the infarct related artery in all catheterized patients. CONCLUSIONS: Isolated ST in leads V7 through V9 identify patients with acute posterior wall myocardial infarction. Early identification of those patients is important for adequate triage and treatment of patients with ischemic chest pain without ST on standard 12-lead ECG.     

Frequency of silent myocardial ischemia with 12-lead ST segment monitoring in the coronary care unit: are there sex-related differences?

BACKGROUND: Ischemia that occurs in the coronary care unit (CCU), whether symptomatic or silent, is associated with significant in-hospital and out-of-hospital complications. Studies have reported that more than 90% of ischemic episodes are silent in patients with unstable angina who are treated in the CCU with maximal medical therapy. Prior reports indicate that women complained more frequently of chest pain than men did. PURPOSE: The aim of this study was to compare the frequency of silent myocardial ischemia in men versus women with use of continuous 12-lead ST segment monitoring in the CCU. A secondary goal was to determine whether silent ischemia was associated with less ST segment deviation as compared with symptomatic ischemia. METHOD: Patients admitted for treatment of acute coronary syndrome in the CCU and who subsequently had 1 or more ischemic events during their monitoring period were selected for this analysis. All patients were continuously monitored (42.5 hours +/- 37.6) in the CCU with the EASI (Zymed Medical Instruments, Camarillo, Calif) 12-lead electrocardiogram (ECG) system that derives 12 leads with use of 3 information channels and 5 electrodes. RESULTS: Of 491 patients, 128 (91 men and 37 women) had at least 1 episode of transient myocardial ischemia. Men and women did not differ in their proportion of chest pain during ischemia (men 27% and women 21%, NS). For both men and women, ST segment deviation was significantly greater during symptomatic ischemia compared with silent ischemia. CONCLUSION: There are no sex-related differences in ischemic events in the CCU in regards to the variables of chest pain and ST magnitude. Therefore, because chest pain is not a reliable indicator of myocardial ischemia in the CCU, regardless of sex, patients should be adequately monitored for ischemic events.     

Prognostic value of 2D echocardiography in patients presenting with acute chest pain and non-diagnostic ECG for ST-elevation myocardial infarction

The purpose of the present study was to test the hypothesis that early detection of regional wall motion abnormalities (WMA) by 2D echocardiography (ECHO) accurately predicts further cardiac events in patients presenting with acute chest pain. A prospective analysis was performed in subjects admitted with the first presentation of acute chest pain and a non-diagnostic ECG for acute ST-elevation myocardial infarction. Patients with known coronary artery disease were excluded. All subjects were contacted by phone for a 30days follow-up regarding cardiac events defined as PCI/CABG, AMI, and death. In 132 consecutive patients (89 male, 43 female) complete data sets consisting of case history (H; abnormal: typical angina), ECG (abnormal: ST-depression, T-inversion, atypical ST-elevation, LBBB), serum markers (TnI; abnormal: elevation of troponin I=0.5 ng/ml), ECHO (abnormal: WMA) and follow-up were available. In 45 patients, 60 cardiac events occurred (three deaths, 24 AMI, 33 PCI/CABG). Positive (PPV; %) and negative predictive values (NPV; %) of ECHO were superior to all other diagnostic tests (P<0.05 each) for adverse cardiac events, evolving AMI or death, and superior to history and ECG for later need of revascularisation (PCI/ACVB). Multivariate analysis revealed that WMA in ECHO predict cardiac events independently of age, gender, and the common combination of investigations (H/ECG/TnI). A significant independent impact of ECHO was also determined for the prediction of AMI/death or PCI/CABG. The study shows that early 2D echocardiography provides superior prognostic information concerning the risk of subsequent complications in patients with acute chest pain and a non-diagnostic ECG for ST-elevation-AMI.     

Vectorcardiography Risk Stratifies Emergency Department Chest Pain Patients with Left Ventricular Hypertrophy on the Initial 12‐Lead ECG

Background: Vectorcardiographic (VCG) measurements of ST‐vector magnitude (VM) and QRS‐vector difference (VD) have been demonstrated to be independent predictors of adverse outcome (AO) and acute myocardial infarction (AMI) in emergency department (ED) chest pain patients with absence of bundle branch block or left ventricular hypertrophy (LVH) on the initial 12‐lead electrocardiogram (ECG). The prognostic value of ST‐VM and QRS‐VD in ED chest pain patients with LVH on the initial 12‐lead ECG has not been previously investigated. Methods: A prospective observational study was performed in 196 consecutive ED chest pain patients with suspected AMI and presence of voltage criteria for LVH on initial ECG who underwent continuous VCG monitoring during the initial evaluation. The optimal baseline ST‐VM value and 2‐hour QRS‐VD value were defined as the most accurate value on the receiver operator characteristic curve (value with lowest false‐negative and false‐positive rate). Thirty‐day AO was defined as AMI, percutaneous coronary intervention, coronary artery bypass grafting (CABG), or cardiac death occurring within 30 days of initial ED visit. Results: Fourteen patients (7.1%) were diagnosed as 24‐hour AMI and 28 patients (14.3%) experienced 30‐day AO. The optimal cut‐off value for predicting 30‐day AO was >124 μV for ST‐VM and >21.7 μV for QRS‐VD. Patients with either a positive ST‐VM or a positive QRS‐VD had 8.8 times increased odds of AMI (95% confidence interval, CI, 1.9–40.3; P = 0.003); 4.3 times increased odds of 30‐day PTCA/CABG (95% CI 1.3–13.8; P = 0.019); and 3.8 times increased odds of 30‐day AO (95% CI 1.6–9.3; P = 0.003). Conclusions: Baseline ST‐VM and 2‐hour QRS‐VD risk stratifies ED chest pain patients with LVH voltage criteria on the initial 12‐lead ECG.     

Right precordial and posterior electrocardiographic leads do not increase detection of ischemia in low-risk patients presenting with chest pain

BACKGROUND: A number of innovative approaches have been investigated for their value in the early detection of acute ischemia or infarction in patients presenting to the emergency department (ED) with chest pain suggestive of a cardiac origin. Prior investigations have demonstrated the utility of adding right precordial and posterior chest leads to the standard 12-lead electrocardiogram (ECG) for identifying right ventricular and posterior wall infarctions in the ED. HYPOTHESIS: To assess the utility of additional ECG leads in low-risk patients presenting to the ED with symptoms suggestive of acute coronary syndromes who are managed in a chest pain evaluation unit (CPEU). METHODS: We studied low-risk patients who presented to the ED with chest pain compatible with myocardial ischemia. Low-risk patients were identified by a normal 12-lead ECG, no arrhythmias or hemodynamic instability, and one negative serum cardiac troponin I. Patients were admitted to the CPEU where a 16-lead ECG was recorded by the addition of 2 right-sided precordial leads (V4R, V5R) and 2 posterior leads (V8, V9) to the standard 12-lead ECG. RESULTS: The 16-lead ECG system was applied to 316 consecutive patients. The study group was a middle-aged population with equal numbers of men and women and an average of 2 cardiac risk factors per patient. The 16-lead ECG demonstrated evidence of myocardial injury in only 1 patient and no evidence of ischemia in any of the 316 patients. CONCLUSION: In patients presenting to the ED with chest pain and evidence of low clinical risk by our criteria, the addition of both right-sided precordial and posterior chest leads to the standard 12-lead ECG did not provide additional information for risk stratification.     

Transient myocardial ischemia is an independent predictor of adverse in-hospital outcomes in patients with acute coronary syndromes treated in the telemetry unit

OBJECTIVE: The purpose of this study was to determine whether transient myocardial ischemia (TMI) is predictive of adverse in-hospital outcomes among patients admitted to a telemetry unit with acute coronary syndrome (ACS). Design and Setting: The study was designed as a prospective clinical trial in a telemetry unit of a large, urban, university medical center. SAMPLE: The sample was comprised of adult patients admitted to the telemetry unit for treatment of acute myocardial infarction, unstable angina, or coronary artery disease warranting cardiac catheterization or percutaneous coronary intervention. METHODS: Continuous 12-lead electrocardiographic (ECG) ST-segment monitoring was initiated in patients admitted to the telemetry unit. TMI was defined as a change in ST amplitude of > or = 100 microV (elevation or depression) in > or = 1 ECG lead lasting > or = 60 seconds, comparing a baseline 12-lead ECG with an event ECG. Frequencies, measurements of central tendency, t test, chi(2) test, and logistic regression analysis were used for data analysis. A P value of <.05 was adopted as the critical value to determine statistical significance. RESULTS: In 237 telemetry unit patients, 39 patients (17%) had ischemia. Overall, 46% of the patients with ischemia had in-hospital complications compared with 10% of the group without ischemia (P <.001). After controlling for other predictors of adverse outcomes (eg, age, gender, Norris prognostic indicator), patients with TMI were 8.5 times more likely to have in-hospital complications (95% CI, 3.71 to 19.71). CONCLUSION: TMI is an independent predictor of in-hospital complications among patients with ACS treated in the telemetry unit setting. Continuous 12-lead ECG ST-segment monitoring provides prognostic information for risk stratification of patients admitted to the hospital for treatment of ACS.     

Postinfarction cardiac rupture: a challenge to try surgical reparation

68 patients deceased from AMI in CCU. They underwent postmortem examination and 12 patients displayed rupture of the free wall of the left ventricle at the sight of the infarction. Clinically, 8 deaths were preceded by an appearance or an increase of chest pain, which was only slightly affected by opiates; 9 patients displayed preterminal sinus rhythm, 2 atrioventricular block and 1 junctional rhythm. In all cases ST-segment was unchanged when the chest pain appeared and death occurred for the 8 patients who felt chest pain in a time interval between 35 and 660 minutes. One could observe a group with early rupture that deceased within 1 hour from the onset of this symptom and 4 patients with late rupture dying in a time-interval between 4 and 11 hours. Pathologically, cardiac hypertrophy and severe coronary alterations were found in all the hearts. Chest pain and unchanged ST-segment at the recorded electrocardiogram often in presence of sinus rhythm in patients showing clinical signs of cardiac hypertrophy should be considered an indication of impending rupture during the course of AMI. Consequently, we must plan a surgical reparation, the only treatment able to save the life of patients who have undergone postinfarction cardiac rupture.     

Application and safety of outpatient ergonovine testing in accurately detecting coronary spasm in patients with possible variant angina

We analyzed the results of 61 consecutive outpatient ergonovine provocation tests to determine the safety and efficacy of such outpatient testing for detecting coronary artery spasm (CAS). Criteria for outpatient testing included: clinical history suggestive of variant angina, noncritical coronary artery disease documented by coronary arteriography, normal exercise treadmill test, no symptomatic arrhythmias, and no history of recent myocardial infarction. All antianginal medications were tapered and stopped. Ergonovine maleate was given as a bolus at 3-minute intervals in consecutive doses of 0.05, 0.10, and 0.25 mg. A positive test was defined as chest pain accompanied by > 0.1 mV ST segment elevation on 12-lead ECG. If pain and ST-segment elevation occurred, intravenous and sublingual nitroglycerin were immediately administered for rellef of myocardial ischemia. Of the 61 patients studied, 10 had positive tests; there were no complications. Follow-up of the 51 patients with negative studies has not revealed cardiac etiology for their chest pain. We conclude that outpatient ergonovine testing is a safe and accurate diagnostic test for identifying CAS in a highly selected population of patients with possible variant angina when performed under carefully controlled conditions.     

Derived 12-lead electrocardiogram in the assessment of ST-segment deviation and cardiac rhythm

BACKGROUND: There are little data on the validation of 12-lead electrocardiogram (ECG) derived by the EASI lead system used for continuous monitoring in critical care settings. OBJECTIVE: The objectives of this study were to determine the accuracy of 12-lead ECG derived by the EASI lead system in the detection of ST-segment deviation and cardiac rhythm compared with the standard 12-lead ECG. METHODS: All patients admitted to the coronary care unit were studied. Kappa statistics was used to calculate the agreement between both ECG systems in the determination of cardiac rhythm and premature ventricular complex morphology. ST-segment analysis was performed in patients with acute coronary syndromes. Pearson correlation was used to correlate the ST-segment deviation between both techniques. The sensitivity and specificity of the determination of significant ST-segment deviation by the EASI lead system were calculated. RESULTS: There were a total of 282 patients enrolled in this study. There was a complete agreement in the interpretation of cardiac rhythm between the 2 methods (kappa = 1). Analysis of ST-segment deviation of 12-lead ECG also showed a significant correlation (correlation coefficient varied from 0.62 in lead I to 0.823 in lead aVF with a P value of <.001 in all leads) between the 2 methods with very high sensitivity and specificity in the detection of significant ST-segment elevation and depression. CONCLUSION: The 12-lead ECG derived by the EASI lead system is an accurate and reliable information for the assessment of ST-segment deviation and cardiac rhythm in critically ill patients.     

Myocardial perfusion imaging with technetium-99m sestamibi in patients with cocaine-associated chest Pain

STUDY OBJECTIVE: To describe the characteristics and outcome in patients presenting to the emergency department with chest pain associated with cocaine use, the majority of whom underwent early rest perfusion imaging. METHODS: From January 1994 to June 1996, 218 patients had 241 ED visits for evaluation of symptoms consistent with myocardial ischemia after cocaine use. High-risk patients (N=25) were admitted directly to the CCU for exclusion of myocardial infarction (MI). Moderate- to low-risk patients (N=216) were promptly injected with technetium-99m sestamibi in the ED and underwent gated myocardial perfusion imaging 60 to 90 minutes later. Moderate-risk patients were observed in the CCU, whereas low-risk patients with negative perfusion imaging results were discharged home directly from the ED. RESULTS: A diagnosis of MI was made in 6 patients, 4 of whom had ECG findings consistent with MI. Of the 216 patients who underwent perfusion imaging, 5 had positive study results, including 2 with MI. None of the 38 patients with negative results after perfusion imaging who were admitted to the CCU had a diagnosis of MI. Only 6 of the 67 patients undergoing stress perfusion imaging had reversible perfusion defects. At 30-day follow-up, there were no cardiac events in patients with negative results after rest perfusion imaging. CONCLUSION: Acute MI is infrequent in patients presenting with cocaine-associated chest pain. Positive results after rest perfusion imaging are uncommon, suggesting that myocardial ischemia is infrequently the cause of cocaine-associated chest pain. Early perfusion imaging may offer an effective alternative to routine CCU admission of patients with cocaine-related cardiac symptoms.