CJEM Articles: myocardial infarction

Objective: We derived a clinical decision rule to determine which emergency department (ED) patients with chest pain and possible acute coronary syndrome (ACS) require chest radiography.

Methods: We prospectively enrolled patients over 24 years of age with a primary complaint of chest pain and possible ACS over a 6 month period. Emergency physicians completed standardized clinical assessments and ordered chest radiographs as appropri ate. Two blinded investigators independently classified chest radi ographs as "normal," "abnormal not requiring intervention" and "abnormal requiring intervention," based on review of the radiol ogy report and the medical record. The primary outcome was abnormality of chest radiographs requiring acute intervention. Analyses included interrater reliability assessment (with κ statistics), univariate analyses and recursive partitioning.

Results: We enrolled 529 patients during the study period between Jul. 1, 2007, and Dec. 31, 2007. Patients had a mean age of 59.9 years, 60.3% were male, 4.0% had a history of con gestive heart failure and 21.9% had a history of acute myocardial infarction. Only 2.1% (95% confidence interval [CI] 1.1%-3.8%) of patients had radiographic abnormality of the chest requiring acute intervention. The κ statistic for chest radiograph classification was 0.81 (95% CI 0.66-0.95). We derived the following rule: patients can forgo chest radiography if they have no history of congestive heart failure, no history of smoking and no abnormalities on lung auscultation. The rule was 100% sensitive (95% CI 32.0%-40.4%) and 36.1% specific (95% CI 32.0%-40.4%). Conclusion: This rule has potential to reduce health care costs and enhance ED patient flow. It requires validation in an independent patient population before introduction into clinical practice.

Objective: We sought to determine the incidence of acute myocardial infarction (AMI) in emergency department (ED) patients with syncope, the characteristics of these AMIs and how helpful the initial electrocardiogram (ECG) was in identifying these cases.

Methods: In a prospective cohort of consecutive patients with syncope, the initial ECG was found to be abnormal using a prespecified definition (any nonsinus rhythm or any new or age- indeterminate abnormalities). Patients were then followed up to identify an AMI diagnosed within 30 days of presentation.

Results: There were 1474 consecutive patient visits for syncope or near-syncope over a 45-month period spanning from Jul. 1, 2000, to Feb. 28, 2002, and Jul. 15, 2002, to Aug. 31, 2004, of which 46 (3.1%) were diagnosed with AMI. The majority of the AMI patients (42) had no ST segment elevation. The initial ECG was abnormal in 37 out of 46 cases. The diagnostic performance of the initial ECG was sensitivity 80% (95% confidence interval [CI] 67%-89%), specificity 64% (95% CI 61%-67%), negative predictive value 99% (95% CI 98%-100%), positive predictive value 7% (95% CI 6%-8%), positive likelihood ratio 2.2 (95% CI 1.6-2.5) and negative likelihood ratio 0.3 (95% CI 0.2-0.5).

Conclusion: The incidence of AMI in patients presenting with syncope is low. A normal ECG has a high negative predictive value, although its sensitivity is limited.

Objective: We sought to determine the diagnostic accuracy of clinical prediction rules to exclude acute coronary syndrome (ACS) in the emergency department (ED) setting.

Methods: We searched MEDLINE, EMBASE, Web of Science and the Cochrane Database of Systematic Reviews. We contacted content experts to identify additional articles for review. Reference lists of included studies were hand searched. We selected articles for review based on the following criteria: 1) enrolled consecutive ED patients; 2) incorporated variables from the history or physical examination, electrocardiogram and cardiac biomarkers; 3) did not incorporate cardiac stress testing or coronary angiography into prediction rule; 4) based on original research; 5) prospectively derived or validated; 6) did not require use of a computer; and 7) reported sufficient data to construct a 2 × 2 contingency table. We assessed study quality and extracted data independently and in duplicate using a standardized data extraction form.

Results: Eight studies met inclusion criteria, encompassing 7937 patients. None of the studies verified the prediction rule with a reference standard on all or a random sample of patients. Six studies did not report blinding prediction rule assessors to reference standard results, and vice versa. Three prediction rules were prospectively validated. Sensitivities and specificities ranged from 94% to 100% and 13% to 57%, and positive and negative likelihood ratios from 1.1 to 2.2 and 0.01 to 0.17, respectively.

Conclusion: Current prediction rules for ACS have substantial methodological limitations and have not been successfully implemented in the clinical setting. Future methodologically sound studies are needed to guide clinical practice.

Objectives: To clarify the benefits, risks and timing of glucose control and intensive insulin therapy in several groups, specifically the neurologic, cardiac and septic populations of patients, commonly seen in the emergency department.

Methods: Electronic search of MEDLINE (1966-2005; once with PubMed and once with Ovid) and Embase (1980-2005) using the terms insulin and glucose combined with emergency medicine, intensive care, cardiology and emergency department.

Results: There is considerable controversy in the literature surrounding the use of strict glucose control in cardiac, neurologic and septic patients. Much of this literature is non-randomized, and the timing of therapy is poorly investigated.

Conclusions: Hyperglycemia is associated with adverse outcomes in acutely ill neurologic, cardiac and septic patients, but it remains unclear whether this is a causative association. Glucose control and intensive insulin therapy may be useful in some patient subgroups; however, controlled trials of aggressive glycemic control have provided insufficient evidence to justify subjecting patients to the real risks of iatrogenic hypoglycemia. We recommend a cautious approach to the control of glucose levels in acutely ill emergency department patients, with a target glucose of below 8 to 9 mmol/L.