Assessment of Patients With Suspected Coronary Artery Disease (CAD): What is the Best Initial Imaging Strategy?

Assessment of Patients With Suspected CAD: What is the Best Initial Imaging Strategy? Cardiac Computed Tomographic Angiography,(CCTA) vs Stress Echocardiography (SE) vs SPECT

Patients who present with chest pain are investigated with tests designed to confirm or exclude the presence of Coronary Artery Disease (CAD), as well as determine risk of poor outcome. It is not known which imaging test would be best when used first for investigating a patient presenting with exertional chest pain. This trial is designed to compare outcomes of the use of coronary CT, stress echocardiography and nuclear perfusion (SPECT) in a pilot study. Patients with no history of coronary disease presenting with chest pain will be randomly assigned to one of the three test modalities as the initial imaging test. The three imaging strategies will be compared regarding the subsequent use of healthcare resources over a year.

This is a pilot study on imaging strategies for diagnosis of coronary artery disease. The pilot trial aims to answer the question "Which non-invasive test (single photon emission computed tomography (SPECT), stress echocardiography or coronary CT angiography (CCTA)) is the best first test in suspected coronary artery disease with respect to patient outcome and downstream health costs?" Patients are randomly assigned to one of the imaging modalities. All imaging and therapeutic procedures in this trial are clinically indicated. The only change from standard patient management is the selection of the initial imaging test. Instead of leaving the selection of the initial imaging test to the referring physician (whose decision is not evidence based), patients presenting with chest pain that fall into the inclusion/exclusion criteria of the study will be randomly assigned to one of the imaging modalities. Patients will also be followed at 1, 6 and 12 months after enrolment to determine outcomes. The three imaging strategies will be compared regarding subsequent use of healthcare resources over a year. In most large cardiac centres, different imaging modalities are performed by different specialists and therefore an operating grant from one imaging specialty rarely covers the costs of other imaging specialties in comparative studies. To ensure a fair comparison between modalities, all modalities have to be equal. Previous comparative trials have been criticized for being biased towards the technique being promoted by the principal investigator. This trial is unique in that the directors of nuclear cardiology, coronary computed tomography and echocardiography are all specialists in their field and are running state-of-the-art services and were all involved in the early planning of this trial and their involvement has ensured trial design meets clinical need. The results of this trial will give insight into planning of a larger multicentre, multi-national study.

Inclusion Criteria:

• Adult Age ≥ 18 years
• Presenting with symptoms suggestive of CAD requiring diagnostic/prognostic workup
• Suitable for Contrast Stress Echocardiography, SPECT and CCTA
• Able and willing to provide consent

Exclusion Criteria:

• Patients with documented CAD (previous invasive angiography, previous STEMI, previous PCI or CABG)
• NSTEMI, ACS within 3 months
• Previous diagnostic imaging tests in the past 6 months
• Women who are pregnant as evidenced by positive pregnancy test
• Breast feeding females
• Significant valvular heart disease (i.e. severe aortic stenosis or regurgitation or severe mitral regurgitation)
• Hemodynamic instability (blood pressure >210/110 ml/Hg or <90/60 mm/Hg)
• Unavailability for follow-up
• Renal insufficiency, eGFR < 30 ml/minute unless on dialysis
• Known allergy to x-ray or echo contrast agents
• Weight exceeding specifications of nuclear equipment (>250 Kg)
• Unable to give informed consent