Emergent diagnosis of acute coronary syndromes: Today's challenges and tomorrow's possibilities

Non-invasive and contemporaneous cardiac imaging in heart failure

This article reviews the current non-invasive cardiac imaging modalities used in the diagnosis and management of heart failure patients. Heart failure is a complex syndrome secondary to functional and structural changes of the heart, with a wide range of possible causes for its onset. Different imaging investigations can inform diagnosis and guide care plans, so nurses across clinical practice will benefit from having knowledge on when these modalities are used. Echocardiography remains the most common investigation due to its low cost and reproducible nature when compared with other methods. It allows quantification of left ventricular function, which is an important prognostic marker in heart failure. Through cardiac magnetic resonance imaging, identification of potential reversible causes is possible, and further identification of underlying causes, when other modalities fail to do so. Finally, computed tomography coronary angiography is the currently recommended test in all patients presenting with typical or atypical anginal symptoms, diagnostically comparable to invasive coronary angiography.

A Whole Blood Molecular Signature for Acute Myocardial Infarction

Chest pain is a leading reason patients seek medical evaluation. While assays to detect myocyte death are used to diagnose a heart attack (acute myocardial infarction, AMI), there is no biomarker to indicate an impending cardiac event. Transcriptional patterns present in circulating endothelial cells (CEC) may provide a window into the plaque rupture process and identify a proximal biomarker for AMI. Thus, we aimed to identify a transcriptomic signature of AMI present in whole blood, but derived from CECs. Candidate genes indicative of AMI were nominated from microarray of enriched CEC samples, and then verified for detectability and predictive potential via qPCR in whole blood. This signature was validated in an independent cohort. Our findings suggest that a whole blood CEC-derived molecular signature identifies patients with AMI and sets the framework to potentially identify the earlier stages of an impending cardiac event when used in concert with clinical history and other diagnostics where conventional biomarkers indicative of myonecrosis remain undetected.

Cardiac Monitoring in the Emergency Department

Patients present to the emergency department (ED) with a wide range of complaints and ED clinicians are responsible for identifying which conditions are life threatening. Cardiac monitoring strategies in the ED include, but are not limited to, 12-lead electrocardiography and bedside cardiac monitoring for arrhythmia and ischemia detection as well as QT-interval monitoring. ED nurses are in a unique position to incorporate cardiac monitoring into the early triage and risk stratification of patients with cardiovascular emergencies to optimize patient management and outcomes.

A 2-hour thrombolysis in myocardial infarction score outperforms other risk stratification tools in patients presenting with possible acute coronary syndromes: comparison of chest pain risk stratification tools

BACKGROUND

Accelerated diagnostic pathways for risk stratification of patients presenting to the emergency department with potential acute coronary syndromes may identify very-low-risk patients safe for early discharge to outpatient care.

METHODS

Patients presenting with potential acute coronary syndrome to the emergency department were prospectively enrolled between November 2007 and April 2010. Patient characteristics in conjunction with 0- and 2-hour biomarkers and electrocardiograms were analyzed according to a 2-hour thrombolysis in myocardial infarction (TIMI) score and 9 other accelerated diagnostic pathways. The primary outcome was acute coronary syndrome by 30 days.

RESULTS

Of 1,000 patients, 362 (36.2%) had a primary outcome. A pathway comprising electrocardiogram, prior ischemic heart disease, 0/2-hour troponin/creatine kinase MB fraction/myoglobin identified the highest proportion (25.0%) as low risk, with 96.1% sensitivity for the primary outcome. A pathway comprising electrocardiogram, history of ischemic heart disease, typical vs atypical symptoms, 0/2-hour troponin was the safest, with 99.7% sensitivity for the primary outcome, but only 9.0% were low risk. A pathway comprising the TIMI score with 0/2-hour troponin and electrocardiograms identified 15.5% as low risk, with a sensitivity of 99.2% for the primary outcome. This compares with standard care in which none were for outpatient care but, 3.3% had a primary outcome postdischarge within 30 days.

CONCLUSION

In this relatively high-risk population, a 2-hour TIMI score safely identified significant numbers of patients suitable for early discharge to outpatient care.

Combination of copeptin and troponin assays to rapidly rule out non-ST elevation myocardial infarction in the emergency department

OBJECTIVES

The aim of this study was to analyze the diagnostic accuracy and the clinical usefulness of the combination of troponin I (cTnI) and copeptin measured at presentation with an automated assay to rapidly rule out non-ST elevation myocardial infarction (NSTEMI) in patients with suspected cardiac chest pain presenting to an emergency department (ED).

METHODS

This study was an ancillary analysis of a prospective observational study. Copeptin and cTnI levels were sampled at presentation in 641 consecutive patients admitted to the ED for chest pain with onset within the last 12 hours and without ST elevation on a 12-lead electrocardiogram (ECG). Copeptin was measured with an automated assay and troponin with conventional assay. The performance of a combination of cTnI and copeptin for NSTEMI diagnosis was studied, the clinical utility was assessed by multivariate analysis, and an area under the curve (AUC) calculation was used to determine accuracy.

RESULTS

NSTEMI was diagnosed in 95 patients (15%). The sensitivity and negative predictive value (NPV) of the combination of copeptin and cTnI measures were 90.4% (95% confidence interval [CI] = 88.2% to 92.7%) and 97.6% (95% CI = 96.4% to 98.7%) versus 55.3% (95% CI = 51.5% to 59.2%) and 92.8% (95% CI = 90.8% to 94.8%) with cTnI alone. The AUC of the combination of copeptin and cTnI was 0.89 (95% CI = 0.85% to 0.92%) and was significantly higher than the AUC of cTnI alone (0.77, 95% CI = 0.72% to 0.82%, p < 0.05). The patient classification was slightly improved when copeptin was added to the usual diagnostic tools used for NSTEMI management.

CONCLUSIONS

In this study, determination of copeptin, in addition to cTnI, improves early diagnostic accuracy of NSTEMI. However, the sensitivity of this combination even using a conventional troponin assay remains insufficient to safely rule out NSTEMI at the time of presentation.