The Effectiveness of Non-ECG-Gated Contrast-Enhanced Computed Tomography for the Diagnosis of Non-ST Segment Elevation Acute Coronary Syndrome

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.

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.

Case report of non-ST-segment elevation myocardial infarction diagnosed in spectral detector-based computed tomography performed for the diagnosis of acute pulmonary embolism

Background

Contrast-enhanced spectral detector-based computed tomography (SDCT) allows for the comprehensive and retrospective analysis. We report a case of pulmonary thromboembolism (PE) accompanied by non-ST-segment elevation myocardial infarction (NSTEMI) diagnosed by SDCT.

Case summary

A 72-year-old man with diabetes mellitus, hypertension, and prostate cancer suddenly developed chest and back pain and had difficulty in breathing at rest. Electrocardiography showed a right bundle branch block without significant ST-segment change. The initial serum troponin I level was 0.05 ng/mL, and the d-dimer level was 14.7 μg/mL. Spectral detector-based computed tomography showed bilateral scattered PE. After admission, his chest pain persisted, and the serum troponin I level 3 h after admission was elevated to 0.90 ng/mL. Reconstruction of SDCT images showed a perfusion defect of the posterolateral left ventricle myocardium. A coronary angiogram showed total occlusion of the obtuse marginal branch (OM); percutaneous coronary intervention was performed. Furthermore, we administered him with oral anticoagulants (OACs) for PE. Spectral detector-based computed tomography tests performed 6 months after the treatment was initiated, until when the dual antiplatelet therapy and OAC therapy were continued, showed improvement in perfusion defects of both pulmonary fields and the myocardium. His treatment was deescalated to single antiplatelet therapy and OAC, and the patient has had a good course.

Discussion

Non-ST-segment elevation myocardial infarction is sometimes difficult to diagnose accurately, especially in the hyper-acute phase or in the OM branch. The reconstruction of spectral images from enhanced SDCT was helpful to diagnose this unique combination of PE and NSTEMI and may be useful for evaluating therapeutic effects in such patients.

A noteworthy clue for diagnosing non-ST-elevation myocardial infarction by computed tomography without ECG synchronization: a case report

Background

Although timely coronary intervention can result in markedly improved clinical outcomes of patients with acute coronary syndrome (ACS), non-ST-elevation (NSTE)-ACS is sometimes difficult to accurately diagnose.

Case presentation

A 52-year-old woman complained of acute chest pain with sudden onset. Both electrocardiography (ECG) and echocardiography showed normal results, and we urgently needed to make a differential diagnosis among critical illnesses such as acute coronary syndrome and nonischemic cardiovascular life-threatening diseases. Contrast-enhanced computed tomography (CT) without ECG synchronization showed evidence of neither aortic dissection nor pulmonary embolism, but regionally reduced contrast enhancement in the posterior myocardium, which were suggestive of myocardial ischemia. Emergency coronary angiography demonstrated severe stenosis of the left circumflex artery, and we achieved favorable revascularization with drug-eluting stent deployment.

Conclusions

We diagnosed a patient with NSTE-ACS in whom contrast-enhanced CT without ECG synchronization was effective for visualization of reduced myocardial perfusion, suggesting ischemic heart disease.

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.

Left ventricular wall findings in non-electrocardiography-gated contrast-enhanced computed tomography after extracorporeal cardiopulmonary resuscitation

Background

Few studies have reported left ventricular wall findings in contrast-enhanced computed tomography (CE-CT) after extracorporeal cardiopulmonary resuscitation (ECPR). This study examined left ventricular wall CE-CT findings after ECPR and evaluated the association between these findings and the results of coronary angiography and prognosis.

Methods

We evaluated out-of-hospital cardiac arrest patients who were treated with ECPR and subsequently underwent both non-electrocardiography-gated CE-CT and coronary angiography at our center between January 2011 and April 2018. Left ventricular wall CE-CT findings were classified as follows: (1) homogeneously enhanced (HE; the left ventricular wall was homogeneously enhanced), (2) segmental defect (SD; the left ventricular wall was not segmentally enhanced according to the coronary artery territory), (3) total defect (TD; the entire left ventricular wall was not enhanced), and (4) others. Successful weaning from extracorporeal membrane oxygenation, survival to hospital discharge, and predictive ability of significant stenosis on coronary angiography were compared among patients with HE, SD, and TD patterns.

Results

A total of 74 patients (median age, 59 years) were eligible, 50 (68%) of whom had initial shockable rhythm. Twenty-three (31%) patients survived to hospital discharge. HE, SD, TD, and other patterns were observed in 19, 33, 11, and 11 patients, respectively. The rates of successful weaning from extracorporeal membrane oxygenation (84% vs. 39% vs. 9%, p < 0.01) and survival to hospital discharge (47% vs. 27% vs. 0%, p = 0.02) were significantly different among patients with HE, SD, and TD patterns. In post hoc analysis, patients with HE patterns had a significantly higher success rate of weaning from extracorporeal membrane oxygenation than those with SD and TD patterns. SD predicted significant stenosis with a sensitivity of 74% and specificity of 94%.

Conclusions

Homogenously enhanced left ventricular wall might be a predictor of good left ventricular function recovery. In contrast, total enhancement defect in the entire left ventricular wall was associated with poor outcomes. Contrast defect matching the coronary artery territory could predict significant coronary artery stenosis with good specificity. The left ventricular wall findings in non-electrocardiography-gated CE-CT after ECPR might be useful for diagnosis and prognostic prediction.