The role of non-invasive imaging in patients with suspected acute coronary syndrome

Coronary CT Angiography CAD-RADS versus Coronary Artery Calcium Score in Patients with Acute Chest Pain

Background The Coronary Artery Disease Reporting and Data System (CAD-RADS) was established in 2016 to standardize the reporting of coronary artery disease at coronary CT angiography (CCTA). Purpose To assess the prognostic value of CAD-RADS at CCTA for major adverse cardiovascular events (MACEs) in patients presenting to the emergency department with chest pain. Materials and Methods This multicenter retrospective observational cohort study was conducted at four qualifying university teaching hospitals. Patients presenting to the emergency department with acute chest pain underwent CCTA between January 2010 and December 2017. Multivariable Cox regression analysis was used to evaluate risk factors for MACEs, including clinical factors, coronary artery calcium score (CACS), and CAD-RADS categories. The prognostic value compared with clinical risk factors and CACS was also assessed. Results A total of 1492 patients were evaluated (mean age, 58 years ± 14 years [standard deviation]; 759 men). During a median follow-up period of 31.5 months, 103 of the 1492 patients (7%) experienced MACEs. Multivariable Cox regression analysis showed that a moderate to severe CACS was associated with MACEs after adjusting for clinical risk factors (hazard ratio [HR] range, 2.3-4.4; P value range, <.001 to <.01). CAD-RADS categories from 3 to 4 or 5 (HR range, 3.2-8.5; P < .001) and high-risk plaques (HR = 3.6, P < .001) were also associated with MACEs. The C statistics revealed that the CAD-RADS score improved risk stratification more than that using clinical risk factors alone or combined with CACS (C-index, 0.85 vs 0.63 [P < .001] and 0.76 [P < .01], respectively). Conclusion The Coronary Artery Disease Reporting and Data System classification had an incremental prognostic value compared with the coronary artery calcium score in the prediction of major adverse cardiovascular events in patients presenting to the emergency department with acute chest pain. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Vliegenthart in this issue.

Virtual (Computed) Fractional Flow Reserve: Future Role in Acute Coronary Syndromes

The current management of acute coronary syndromes (ACS) is with an invasive strategy to guide treatment. However, identifying the lesions which are physiologically significant can be challenging. Non-invasive imaging is generally not appropriate or timely in the acute setting, so the decision is generally based upon visual assessment of the angiogram, supplemented in a small minority by invasive pressure wire studies using fractional flow reserve (FFR) or related indices. Whilst pressure wire usage is slowly increasing, it is not feasible in many vessels, patients and situations. Limited evidence for the use of FFR in non-ST elevation (NSTE) ACS suggests a 25% change in management, compared with traditional assessment, with a shift from more to less extensive revascularisation. Virtual (computed) FFR (vFFR), which uses a 3D model of the coronary arteries constructed from the invasive angiogram, and application of the physical laws of fluid flow, has the potential to be used more widely in this situation. It is less invasive, fast and can be integrated into catheter laboratory software. For severe lesions, or mild disease, it is probably not required, but it could improve the management of moderate disease in 'real time' for patients with non-ST elevation acute coronary syndromes (NSTE-ACS), and in bystander disease in ST elevation myocardial infarction. Its practicability and impact in the acute setting need to be tested, but the underpinning science and potential benefits for rapid and streamlined decision-making are enticing.

Coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) imaging in the assessment of patients presenting with chest pain suspected for acute coronary syndrome

Acute chest pain is an important clinical challenge and a major reason for presentation to the emergency department. Although multiple imaging techniques are available to assess patients with suspected acute coronary syndrome (ACS), considerable interest has been focused on the use of non-invasive imaging options as coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR). According to several recent evidences, CCTA has been shown to represent a useful tool to rapidly and accurately diagnose coronary artery disease (CAD) in patients with low to intermediate cardiovascular risk. CCTA examination has the unique ability to non-invasively depict the coronary anatomy, not only allowing visualization of the lumen of the arteries in order to detect severe stenosis or occlusion responsible of myocardial ischemia, but also allows the assessment of coronary artery wall by demonstrating the presence or absence of CAD. However, routine CCTA is not able to differentiate ischemic from non-ischemic chest pain in patients with known CAD and it does not provide any functional assessment of the heart. Conversely, CMR is considered the gold standard in the evaluation of morphology, function, viability and tissue characterization of the heart. CMR offers a wide range of tools for diagnosing myocardial infarction (MI) at least at the same time of the elevation of cardiac troponin values, differentiating infarct tissue and ischemic myocardium from normal myocardium or mimicking conditions, and distinguishing between new and old ischemic events. In high-risk patients, with acute and chronic manifestations of CAD, CMR may be preferable to CCTA, since it would allow detection, differential diagnosis, prognostic evaluation and management of MI.