Imaging in the evaluation of the patient with suspected acute coronary syndrome

Noninvasive Imaging Techniques to Aid in the Triage of Patients with Suspected Acute Coronary Syndrome: A Review

The evaluation, treatment, and disposition of patients with symptoms suggestive of acute coronary syndrome (ACS) in the Emergency Department continues to be a clinical challenge. Many patients with suggestive symptoms are admitted to the hospital to rule out a myocardial infarction by serial enzyme tests and EKGs and receive an expedited work-up for ischemia. However, the diagnosis can be difficult, given the wide range of potentially atypical symptoms that can signal ACS, which remains a major clinical risk for patients and a liability risk for emergency physicians. This article reviews imaging technologies such as echocardiography and nuclear perfusion imaging used currently in the diagnosis of ACS and rapidly advancing technologies such as CT and MRI that may be able to visualize calcifications, plaques, occlusions, and infarctions noninvasively in real time. Some noninvasive tests used to complete an ischemia work-up after serial enzyme testing and EKGs, such as exercise EKG, stress echocardiography, and stress perfusion imaging, also are reviewed.

Chest Pain Evaluation in the Emergency Department: Can MDCT Provide a Comprehensive Evaluation?

OBJECTIVE

The purpose of our study was to determine whether MDCT can provide a comprehensive assessment of cardiac and noncardiac causes of chest pain in stable emergency department patients.

SUBJECTS AND METHODS

Patients with chest pain who presented to the emergency department without definitive findings of acute myocardial infarction based on history, physical examination, and ECG were recruited immediately after the initial clinical assessment. For each patient, the emergency department physician was asked whether a CT scan would normally have been ordered on clinical grounds (e.g., to exclude pulmonary embolism). Each consenting patient underwent enhanced ECG-gated 16-MDCT. Ten cardiac phases were reconstructed. The images were evaluated for cardiac (coronary calcium and stenosis, ejection fraction, and wall motion and perfusion) and significant noncardiac (pulmonary embolism, dissection, pneumonia, and so forth) causes of chest pain. Correlation was made between the presence of significant cardiac and noncardiac findings on CT and the final clinical diagnosis based on history, examination, and any subsequent cardiac workup at the 1-month follow-up by a consensus of three physicians.

RESULTS

Sixty-nine patients met all criteria for enrollment in the study, of whom 45 (65%) would not otherwise have undergone CT. Fifty-two patients (75%) had no significant CT findings and a final diagnosis of clinically insignificant chest pain. Thirteen patients (19%) had significant CT findings (cardiac, 10; noncardiac, 3) concordant with the final diagnosis. CT failed to suggest a diagnosis in two patients (3%), both of whom proved to have clinically significant coronary artery stenoses. In two patients (3%), CT overdiagnosed a coronary stenosis. Sensitivity and specificity for the establishment of a cardiac cause of chest pain were 83% and 96%, respectively. Overall sensitivity and specificity for all other cardiac and noncardiac causes were 87% and 96%, respectively.

CONCLUSION

ECG-gated MDCT appears to be logistically feasible and shows promise as a comprehensive method for evaluating cardiac and noncardiac chest pain in stable emergency department patients. Further hardware and software improvements will be necessary for adoption of this paradigm in clinical practice.

The use of CTA in the chest pain center: a perspective

Suitable imaging methods to reliably rule out coronary artery disease as the underlying condition might be beneficially applied in the workup of patients with acute chest pain. The temporal and spatial resolution of computed tomgraphy and electron beam computed tomography has seen continuous improvements over the past years. Current scanner generations permit relatively reliable visualization of the coronary arteries and several studies have demonstrated a high negative predictive value to rule out coronary artery stenoses. Even though applications in the context of acute coronary syndromes have not yet been specifically evaluated, it seems likely that computed tomography imaging may develop into a tool that can be integrated into the workflow in chest pain centers once appropriate studies have been performed.