Acute coronary syndrome: evaluation of detection capability using non-electrocardiogram-gated parenchymal phase CT imaging

Acute coronary syndrome on non-electrocardiogram-gated contrast-enhanced computed tomography

It is not rare for acute coronary syndrome (ACS) patients to present with symptoms that are atypical, rather than chest pain. It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms, normal initial biomarkers of myocardial necrosis, and normal or nondiagnostic electrocardiograms (ECGs). Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS, it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients. However, several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT. A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms. In order to avoid inappropriate management for this life-threatening event, clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.

Diagnostic Accuracy of Coronary Artery Occlusion and Myocardial Perfusion Defect on Non-Gated Enhanced Chest CT in Predicting Acute Myocardial Infarction

The purpose of this study was to evaluate the diagnostic accuracy of coronary artery occlusion (CAO) and myocardial perfusion defect (MPD) identified on non-gated enhanced chest CT in patients with acute myocardial infarction (AMI). We retrospectively assessed 99 patients with AMI (group 1, n = 33) and without AMI (group 2, n = 66) who underwent non-gated chest CT. We analyzed the presence of MPD and CAO on non-gated chest CT. MPD on the CT was categorized using a three-point scale (0 = no definite MPD; 1 = probable artifact or questionable MPD; 2 = probable MPD). Presence of CAO was defined as an abrupt change of contrast enhancement in a coronary artery segment with no or minimal coronary motion on the CT. There were 42.4% and 12.1% patients with probable MPD (p = 0.002), and 18.2% and 0% patients with CAO (p = 0.001) in groups 1 and 2, respectively. Probable MPD alone and simultaneous presence of CAO and probable MPD to predict AMI resulted in sensitivity, specificity, negative predictive value, and positive predictive valve of 42.4%, 87.9%, 75.3%, and 63.6%, respectively, and 12.1%, 100%, 69.5%, and 100%, respectively. In conclusion, probable MPD alone on non-gated chest CT demonstrated a relatively low sensitivity, high specificity, and modest positive predictive value for the prediction of AMI on non-gated enhanced chest CT. Although it is rare, simultaneous presence of CAO and probable MPD had a high positive predictive value to predict AMI on non-gated enhanced chest CT.

Impact of delayed hyperenhancement obtained by non-contrast computed tomography following coronary angiography in patients undergoing extracorporeal cardiopulmonary resuscitation

Background

Extracorporeal cardiopulmonary resuscitation (ECPR) has the potential to improve outcomes in patients with refractory cardiac arrest. However, the outcome is difficult to predict on admission. Recent reports have described early evaluation of myocardial damage in patients with acute myocardial infarction by detecting delayed enhancement in non-contrast computed tomography (CT) following coronary angiography (CAG). We investigated the impact of delayed hyperenhancement obtained by non-contrast CT following CAG in patients with ischaemic and non-ischaemic cardiovascular diseases who underwent ECPR for refractory cardiac arrest.

Methods

Forty-two patients who underwent ECPR, CAG, and postprocedural CT for refractory cardiac arrest in our institute were retrospectively enrolled. Two blinded readers independently and semi-quantitatively judged whether hyperenhancement was present or absent in non-contrast axial CT images following CAG. We evaluated the relationship between in-hospital death and delayed hyperenhancement.

Results

The identification of delayed hyperenhancement was highly consistent between the two readers (kappa ​= ​0.71). The survival rate was 21.4% in this cohort. The only significant difference between the survival group and in-hospital death group was the presence of delayed hyperenhancement, which was detected only in the in-hospital death group (p ​= ​0.03). The prevalence of cardiac death was higher in patients with than without delayed hyperenhancement. Delayed hyperenhancement was observed even in areas perfused by non-obstructive coronary arteries.

Conclusions

Delayed hyperenhancement of the left ventricular wall on non-contrast CT imaging following CAG might help to predict in-hospital death in patients undergoing ECPR for refractory cardiac arrest.

ACR Appropriateness Criteria® Chest Pain-Possible Acute Coronary Syndrome

Chest pain is a frequent cause for emergency department visits and inpatient evaluation, with particular concern for acute coronary syndrome as an etiology, since cardiovascular disease is the leading cause of death in the United States. Although history-based, electrocardiographic, and laboratory evaluations have shown promise in identifying coronary artery disease, early accurate diagnosis is paramount and there is an important role for imaging examinations to determine the presence and extent of anatomic coronary abnormality and ischemic physiology, to guide management with regard to optimal medical therapy or revascularization, and ultimately to thereby improve patient outcomes. A summary of the various methods for initial imaging evaluation of suspected acute coronary syndrome is outlined in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.