Department’s census was approximately 74, 000 in 2004. Smear-positive cases fromthe databases of the Haematology Department and the Malaria Reference Laboratory,London, were collected for analysis. Ethics approval was obtained and theAutomobile Associationª granted copyright permission for the use of their road mapto locate patients.

Results: 184 patients with smear-positive Imported Malaria were identified fromJanuary 1984 to November 2002. Five (5) patients had permanent addresses outsidethe region. The majority were male patients (67.8%). The age profiles for male andfemale patients were: mean 38.8 vs. 48.2 years, mode 20 vs. 60 years, and age rangingfrom 3-80 vs. 3-71 years respectively. P. vivax (58.1%) and P. falciparum (34.8%)accounted for the bulk of imported cases. P. malariae and P. ovale had 3.3% eachwith one case unidentified. The majority of patients were diagnosed between two tosix weeks of developing symptoms but some patients with P. vivax were diagnosedseveral months after their last foreign travel. No patient with Falciparum malaria wasdiagnosed after six weeks of developing symptoms. A patient, of European descent,had 20% falciparum parasitemia and died of Cerebral Malaria. 85.9% of importedfalciparum cases were from sub-Sahara Africa, whilst 92.5% of imported vivax caseswere from South Asia. The majority of patients were of non-European descent butmore patients of European descent were presenting with the disease since 2000.69.5% of 58 cases were non-complaint with anti-malarial chemoprophylaxis. Themalarious mosquito species, An. maculipennis complex, (which include the An.atroparvus), and the An. clavinger, were identified in the region. They were located insustainable sites within a five (5)-mile perimeter of human population despite the factthat their habitants are shrinking.

Conclusion: A nineteen-year review of imported malaria into the Medway Regionshowed that infected individuals were living within travelling distance of endogenousmalarious mosquitoes. A resurgence of endogenous malaria is possible if the balancebetween environmental and human conditions, and habitat destruction are optimise.A review of current vector surveillance and habitat control, anti-malarialchemoprophylaxis compliance, and the introduction of innovative measures toimprove drug compliance are needed in light of the global spread of malaria.

210 Reliability of Three Sets of Cardiac Enzymes in the

Setting of Acute Chest Pain in Patients at Low

Risk for Acute Coronary Syndrome in the

Emergency Department

Papa L, Shaw CR, Rees E, Goldfeder B, Meurer D, Seaberg D, University of Florida,

Gainesville, FL

Introduction: Identification of acute coronary syndrome in low risk patients withacute chest pain in the emergency department (ED) is a common and difficultchallenge for emergency physicians. Although a number of diagnostic technologieshave been described to aid in this triage process, each of these tests or technologies haslimitations. Too commonly there is a reliance on cardiac enzymes alone to assessACS. We sought to determine how accurate three sets of cardiac enzymes were indetecting acute coronary syndrome in low risk patients with chest pain presenting toour ED.

Objective: To test the performance of three sets of cardiac enzymes for assessingacute coronary syndrome in low risk patients with acute chest pain in the ED.

Methods: This study was designed as a prospective observational cohort fromMarch 2004 through February 2005 in a tertiary care teaching hospital. Consecutiveadult ED patients presenting with chest pain with a low TIMI score and at low riskfor Acute Coronary Syndrome (ACS) were entered into a clinical chest pain protocol.As part of the clinical protocol ED patients had three consecutive sets of cardiacenzymes (CK-MB and troponin T) and concommitant ECG’s at 0,3 and 6 hours ofpresentation. Based on these results, patients were either admitted or discharged andan exercise treadmill stress test (EST) was performed within 72 hours of presentation.Clinical variables, ECG, cardiac enzymes and the result of the EST were recorded adata collection forms. The primary outcome was the result of the EST. A positiveenzyme result was defined as any elevation in the cardiac markers during any of thetime points. Data was analyzed using descriptive statistics and appropriate univariatetechniques and using 2x2 tables.

Results: Of the 524 eligible patients who completed the protocol, 361 (69%) hada negative stress test, 89 (17%) had a positive stress test, and the remaining 74 (14%)of the patients had a stress test that was inadequate. For the analysis we included 450of patients having either a firm positive or negative EST result and compared them tothe enzyme results. The cardiac enzymes had a sensitivity of 11% in and a specificityof 91% in predicting a positive EST with an overall accuracy of 75%. The positivepredictive value was 24%, and the negative predictive value was 81%.

Conclusions: Diagnostic adjuncts such as cardiac enzymes must be used carefullyto diagnose acute coronary syndrome in low risk patients. Our study suggests that

reliance on negative cardiac biomarkers in isolation will contribute to the failure torecognize ACS in low risk patients. Clinical pathways involving several diagnosticmodalities to diagnose ACS will lead to fewer misdiagnosed myocardial infarctions,and fewer adverse cardiac events.

Research Forum Abstracts

Volume 46, no. 3 : September 2005

211 Diagnostic Accuracy of Resting Magnetocardio-

graphy in a Cohort of Moderately to Severely

Obese Emergency Department Chest Pain

Observation Unit Patients

Giraldez EM, Smars PA, Baez AA, Madsen BE, Gertzen HC, Mayo Clinic,

Rochester, MN

Study Objectives: To demonstrate the diagnostic accuracy of theMagnetocardiograph (MCG) device as compared to that of a standard 12-leadElectrocardiogram (ECG) for detecting the presence or absence of ischemia inmoderate to severely obese patients presenting with chest pain of unknown etiology.

Methods: This was a prospective, IRB-approved study conducted between April2004 and April 2005. The study Population consisted of patients 18 years and older,with chest pain and suspicion of obstructive coronary artery disease. A 12 lead ECGand a resting 9-channel MCG (CardioMag Imagingª, Schenectady, NY) wasperformed on each subject in a non-shielded environment. Automated analysis wasperformed which produced determination of ischemia based on established criteria.Body Mass Index (BMI) was utilized to stratify obesity categories [moderate obesity(BMI 30.0 to 34.9), severe obesity (BMI 35.0 to 39.9)]. Patients were enrolled fromthe emergency department at a major academic medical center. Descriptive statisticsand confidence intervals were used to present group characteristics. Sensitivity andSpecificity measurements were performed.

Results: 35 obese patients were enrolled, 29 had an adequate MCG exam. Meanage: 55.6 . Mean BMI: 35.3. Thirteen of the 29 (50.4%) patients were found to haveischemic heart disease as diagnosed by cardiac stress testing and/or angiography out ofthese MCG detected 11, yielding a Sensitivity of 0.85 (0.54-0.97) and Specificity0.69 (0.41 to 0.88) compared to the standard ECG in this cohort [Sensitivity 0.6(0.33 to 0.82) Specificity 0.75 (0.50 to 0.90)].

Conclusion: Magnetocardiography appears to show superior diagnostic accuracywhen compared to the standard ECG in this cohort of moderate to severely obesepatients.

212 Patterns and Correlates of Acute (\24 Hours) Use of

Beta-Blockers for Non-ST-Segment Elevation Acute

Coronary Syndromes: Results from the CRUSADE

Initiative

Miller CD, Mulgund J, Hoekstra JW, Santos R, Pollack CV Jr, Gibler WB,

Peterson ED, Roe MT, Wake Forest University, Winston-Salem, NC; Duke Clinical

Research Institute, Durham, NC; Pennsylvania Hospital, University of

Pennsylvania School of Medicine, Philadelphia, PA; University of Cincinnati,

Cincinnati, OH

Study Objectives: Beta-blockers (BB) have a Class IB recommendation for thetreatment of patients with non-ST-segment elevation acute coronary syndromes(NSTE ACS), but utilization patterns for BB in this population have not been wellcharacterized.

Methods: We evaluated acute (within 24 hours) use of BB from 2001-2004among 72,054 patients with NSTE ACS (elevated CK-MB or troponin levels) from509 hospitals in the United States included in the CRUSADE Quality ImprovementInitiative. Patients with contraindications to BB use, those who transferred in or outof participating institutions, and those with missing data on BB use were excluded.Variables associated with acute BB use were determined using the generalizedestimating equations method.

Results: Of 72,054 patients, 59,442 (82.5%) received BB within 24 hours.Patients who received acute BB were younger, less commonly female, more likely tobe admitted to a cardiology inpatient service, and less likely to have prior congestiveheart failure (CHF) and signs of CHF on presentation; they more commonly hadhypertension, prior myocardial infarction, and prior percutaneous coronaryintervention (PCI) (Table). Home BB use before hospital presentation was denotedin 44.6% of patients who received acute BB vs. 21.0% of patients who did not receiveacute BB. Patients who received acute BB were more likely to receive otherguidelines-recommended acute medications (aspirin, heparin, and glycoproteinIIb/IIIa inhibitors) and more likely to undergo cardiac catheterization andin-hospital revascularization procedures.

Annals of Emergency Medicine S59