Chest pain represents a common reason for consultation to emergency room. This symptom can be explained by a broad spectrum of conditions, from benign musculoskeletal or esophageal pain to life-threatening disease such as aortic dissection, pulmonary embolism, and myocardial infarction.
There are already different diagnostic tools to quickly identify most dangerous diseases, for example electrocardiogram, blood samples with specific markers of cardiac injury, chest X-ray and echography. In case a doubt of disease is raised after the first clinical evaluation, it is possible to proceed with more complex, expensive and invasive examinations, namely a computed tomography (CT) scan or an invasive coronary angiography (ICA).
CT scan allows the diagnosis of various conditions such as pleural, pulmonary, pericardial and vascular disease such as pneumonia, pneumothorax, pleural and pericardial fluid, pulmonary embolism (PE), acute aortic dissection (AOD). In order to see the pulmonary, aortic and coronary arteries, a contrast injection is needed. Moreover, since the heart and the aortic root are continuously moving, specific technical measures to obtain good quality images are needed.
Recently, a new CT scan system has been developed. It allows to obtain good quality images of the heart and aortic root using an estimated heart rhythm, without ECG-gating. This allows to perform a CT scan of the heart in a reduced amount of time, and without need for controlling heart rate. Moreover, it is possible to obtain information on both aortic, coronary, and pulmonary artery with the same contrast injection. This may be of great interest in the context of patients presenting at the emergency room with chest pain and with a suspicion of pulmonary embolism, myocardial infarction, or aortic dissection, since with a single fast exam it is possible to rule out all these conditions.
Coronary arteries are very small vessels, and the accuracy of this new technique in identifying a significant obstruction is still to be proved. At present, patients with chest pain and a suspicion of myocardial infarction undergo an invasive coronary angiography. If this new tool proves to be reliable, it will be possible to reduce the number of useless invasive examination in patients in which the presence of coronary artery disease (CAD) is ruled-out. In addition, the CT scan can help quickly and effectively plan treatment when worrying abnormalities are detected in the coronary arteries that are associated with a higher risk.
Therefore, this clinical trial (further on referred to as "trial") will evaluate the investigational medicinal product (IMP), ECG-less Revolution Apex Elite system (GE Healthcare, Waukesha, WI -USA) for the diagnosis of coronary artery disease. The purpose of this trial is to learn about: the accuracy of this new CT system compared to the gold standard invasive coronary angiography in diagnosing coronary artery disease. The number of patients receiving an alternative diagnosis such as pulmonary embolism, aortic dissection, pulmonary, pleural or pericardial disease will be evaluated. Finally, the prognostic predictive value of the CT compared with ICA, in predicting myocardial infarction, coronary revascularization, and cardiac death at a follow-up of 18 months will be assessed. Patient will undergo a computer tomography examination with this new technique, evaluating both pulmonary, aortic, and coronary arteries. Then, as indicated by current guidelines, they will undergo an invasive coronary angiography.
Age ≥ 30 years old
ECG abnormality;
positive rule-in criteria according to the ESC guidelines (hs-cTnT ≥ 52 in at least one assay or 1h ∆ ≥ 5);
troponine value in the "observe pathway" (hs-cTnT ≥ 12 in at least one assay or 1h ∆ ≥ 3) AND a high clinical suspicion of MI.
Indication for urgent ICA (ST-elevation, hemodynamic or electric instabil-ity, refractory chest pain, mechanical complications)
eGFR < 30 ml/min
Previous coronary stenting
Previous CABG
Single group
Non-ECG-gated computed tomography
RadiationScanning with a Revolution Apex Elite system (GE Healthcare, WI, USA), using hyperdrive pulmonary CT angiography (523mm/s with 0.28s/rotation gantry speed). Images will be acquired using the ECG-less Cardiac software (GE Healthcare, WI, USA), without the need for patient-attached ECG leads. The system uses a wide detector coverage of 160mm to provide full heart coverage and a fast gantry speed of 0.23 seconds per rotation to perform imaging in a single cardiac cycle. An estimation of the heart rhythm must be provided, based on the heart rhythm the scanner simulates an ECG signal. This simulated ECG signal provides virtual gating of the scan. Advanced software tools including SmartPhase (automated phase selection) and SnapShot Freeze 2 (optimized volume registration) will be used. After a short delay of 5-12 sec, allowing contrast to pass from the pulmonary circulation into the aorta and coronary arteries, a coronary CT angiography will be performed using the same contrast bolus.
Diagnostic accuracy of ECG-less CCTA for detecting obstructive coronary artery disease (defined as luminal narrowing ≥ 50%), compared to invasive coronary angiography
In both studies, sensitivity, specificity, positive and negative predictive value will be calculated. Diagnostic accuracy will be assessed using the McNemar test to compare CCTA with ICA. Cohen's Kappa agreement test will be used to evaluate agreement in diagnostic categorization between the two modalities.
Accuracy of CCTA in detecting high-risk CAD such as LM, proximal LAD and multivessel disease compared to invasive coronary angigoraphy
Accuracy of CCTA in detecting high-risk CAD such as LM, proximal LAD and multivessel disease compared to invasive coronary angigoraphy
Possibility of CT-derived FFR in ECG-less CCTA
We will explore the feasibility of performing fractional flow reserve (FFR)-CT analysis on ECG-less CCTA images. The added diagnostic value of FFR-CT will be evaluated comparing diagnostic accuracy of CCTA with and without FFR, using ICA as the reference.
Other conditions rather than CAD
The diagnosis of conditions other than CAD such as aortic dissection, pulmonary embolism, pneumonia, pleural fluid, pneumothorax, and pericardial fluid will be recorded
Outcome prediction of ECG-less CCTA compared to ICA
A follow-up at 18 months will assess the occurrence of adverse events (ischemia-driven revascularization, myocardial infarction, and cardiac death). The groups of patients with positive and negative CT scan and ICA will be compared using Chi-squared test or Fisher's exact test as appropriate. For the analysis of binary outcomes, logistic regression will be utilized to establish the binary classifier for ROC curve analysis. Kaplan-Meier curves will be used to describe the event-free survival; differences between groups will be tested with the Log-Rank test. Renal function will be monitored by assessing eGFR at the time of hospitalization, before discharge, and at 18 months.
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