Dynamic Computed Tomography Myocardial Perfusion Imaging for Detection of Coronary Artery Disease

Withdrawn before enrolling · Not applicable

Conditions studied: Coronary Artery Disease, Ischemia

In brief

Coronary artery computed tomographic angiography (CTA) is a widely used, highly accurate technique for the detection of coronary artery disease (CAD), with sensitivity and negative predictive values of over 90% (1-4). Patients with normal CTA findings have an excellent prognosis and do not require further testing for CAD (5). However, like invasive coronary angiography (QCA), CTA is an anatomic test and, unless lesions are very severe (\>90% stenosis), cannot reliably predict the impairment of flow (functional significance) of intermediate grade stenoses. For this reason, in approximately 15-25% of patients, additional functional testing may be required after CTA, usually in the form of stress testing (6-8). Stress testing is commonly done by exercise or pharmacologic stress with electrocardiographic monitoring and often, imaging of myocardial perfusion by nuclear scintigraphy (MPI) or detection of abnormal contraction by echocardiography. This requires a separate procedure, entailing time, expense and limited risk. Furthermore, in patients with previously known CAD, CTA alone is not an adequate test, because in most cases there are multiple lesions that are possible sources of ischemia. Over the last 10 years, these investigators and others around the world have developed a method of imaging myocardial perfusion by CT (CTP). This test is an adjunct to the usual Cardiac Computed Tomography Angiography (CCTA) procedure and can be done immediately thereafter, using conventional pharmacologic stress agents. It has demonstrated accuracy in many single center trials, and in this large multicenter study, the CORE320 trial (9,10) which showed a high accuracy in predicting the combined results of QCA plus MPI testing and a second multicenter trial established non-inferiority of myocardial CTP compared with nuclear stress testing (11,12). Additionally, this investigator group has published a direct comparison of diagnostic performance of myocardial CTP imaging and SPECT myocardial perfusion imaging and demonstrated superior diagnostic performance of CTP imaging compared with SPECT for the diagnosis of significant disease on invasive angiography (13). CTP images can be acquired with two different approaches: static or dynamic. In the CORE320 study, the CTP protocol used static acquisition method. The static CTP method, samples a snapshot of the iodine distribution in the blood pool and the myocardium over a short period of time, targeting either the upslope or the peak of contrast bolus. The notion behind this is that, at the upslope of the contrast, the difference in attenuation value of the ischemic and remote myocardium is at the maximum which enables for qualitative and semi-quantitative assessment of myocardial perfusion defects. The static CTP, however, does not allow for direct quantification of the myocardial blood flow (MBF). One of the drawbacks of static CTP lies in the acquirement of only one sample of data and the possibility of mistiming of the contrast bolus that results in poor contrast-to-tissue ratios by missing the peak attenuation (14). Output and flow rate of the contrast material may affect bolus timing. In addition, the acquisition of data from sequential heartbeats affects the attenuation gradient and may result in a heterogeneous iodine distribution, mimicking perfusion defects (15). Furthermore, the static CTP is limited in detection of balanced ischemia, where the perfusion of the entire myocardium is impaired and therefore there is no reference remote myocardium for comparison for semi-quantitative or qualitative static methods of CTP interpretation. Dynamic CT perfusion imaging uses serial imaging over time to record the kinetics of iodinated contrast in the arterial blood pool and myocardium. This technique allows for multiple sampling of the myocardium and the blood pool and creating time attenuation curves (TAC) by measuring the change in CT attenuation over time. Mathematical modelling of TACs permits for direct quantification of MBF. Despite its advantages, the use of dynamic CTP were limited in the past. A high temporal resolution and high number of detectors are required for dynamic CTP to allow for entire myocardial coverage, and in order to obtain multiple consecutive images at high heart rates(16,17). But the main challenge of dynamic CTP acquisition was the high radiation dose associated with this technique. Nevertheless, with the introduction of the cutting-edge 320 detector CT scanning systems with fast gantry rotation the issue of the cardiac coverage is eliminated(17). The second-generation 320-row scanners also permit the quantification of the MBF with dynamic CTP acquisition with relatively low-dose of radiation(18,19). In this study the investigators aim to evaluate the feasibility, safety and accuracy of the low-radiation dose dynamic myocardial CT perfusion compared to static CTP approach to detect hemodynamically significant coronary artery disease.

Key facts

Study ID: NCT03324308
Run by: Johns Hopkins University
People needed: 0
Starts: 2018-03-30
Expected to finish: 2022-05-08
Last updated by the study team: 2024-02-16

Who can join

Age: 45 and older, up to 85. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

Clinical indication for invasive coronary angiography or CT angiography
Documented coronary artery disease defined as presence of one or more of the following:
CAD documented by invasive coronary angiography or CT angiography
History of typical stable angina and receiving guideline-driven therapy for coronary artery disease for ≥ 1 month prior to consent
History of hospitalization for unstable angina with no active acute coronary syndrome within 48 hours prior to scan
Refractory angina defined as marked limitation of ordinary physical activity or inability to perform ordinary physical activity without discomfort, with an objective evidence of myocardial ischemia and persistence of symptoms despite optimal medical therapy, life style modification treatments, and revascularization therapies
Able to understand and willing to sign the Informed Consent Form.

You may not qualify if…

Known allergy to iodinated contrast media
History of contrast-induced nephropathy
History of multiple myeloma or previous organ transplantation
Elevated serum creatinine (> 1.5mg/dl) OR calculated creatinine clearance of < 60 ml/min (using the Cockcroft-Gault formula)
Atrial fibrillation or uncontrolled tachyarrhythmia, or advanced atrioventricular block (second or third degree heart block)
Evidence of severe symptomatic heart failure (NYHA Class III or IV); Known or suspected moderate or severe aortic stenosis
Previous coronary artery bypass or other cardiac surgery
Coronary artery intervention (PCI) within the last 6 months
Known or suspected intolerance or contraindication to beta-blockers including:
Known allergy to beta-blockers
History of moderate to severe bronchospastic lung disease (including moderate to severe asthma)
Severe pulmonary disease (chronic obstructive pulmonary disease) with the use of inhaled bronchodilators over the past year
Presence of any other history or condition that the investigator feels would be problematic
History of high radiation exposure defined as ≥2 nuclear or CT studies or ≥ 5.0 reml within 18 months prior to the scan
Does the patient have active acute coronary syndrome within 48 hours prior to consent?
Typical, prolonged (>20 minute) rest angina at admission
Angina equivalent symptoms compatible with ischemia plus abnormal cardiac enzymes
Prolonged rest chest pain (>20 minutes) resolved before admission plus prior ischemic ECG changes
Rest chest pain < 20 minutes relieved with nitrates in the prior 48 hours plus prior ischemic ECG changes.
If yes to any of the above, Calculate Thrombolysis in Myocardial Infarction (TIMI) risk score:
If TIMI risk score ≥ 5 OR elevated cardiac enzymes in the 72 hours prior patient is excluded.
If TIMI risk score is <5 and cardiac enzymes are normal patient is included.
If all of above are no then patient is included.
Implantable cardioverter-defibrillator (but not pacemakers) within the imaging field of view
Contraindications to vasodilator stress agents:

Where it is running

Johns Hopkins Unversity School of Medicine — Baltimore, Maryland, United States

Full record on ClinicalTrials.gov

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