Impact of Stress CT Myocardial Perfusion on Downstream Resources and Prognosis

The use of cardiac computed tomography angiography (CCTA) is usually suggested in low to intermediate risk for its diagnostic and prognostic role to rule out CAD with low radiation exposure. In the setting of intermediate to high risk patients, the addition of functional information is prognostically useful and, in patients with previous history of percutaneous coronary intervention (PCI), functional strategy has been shown to be more cost-effective as compared to anatomical assessment CT myocardial perfusion imaging (CTP) represents one of the newly developed CT-based techniques, combining both anatomical and functional evaluation of CAD in a single imaging modality. More recently, stress CTP was shown to provide additional diagnostic value as compared to CCTA alone in intermediate to high risk patients. The purpose of this study will be to evaluate the usefulness and impact of combined evaluation of coronary artery anatomy and myocardial perfusion with CCTA+CTP in intermediate to high risk patients for suspected CAD or with known disease in terms of clinical decision-making, resource utilization, and outcomes in a broad variety of geographic areas and patient subgroups.

CTP-PRO study is a cooperative, international, multicentre, prospective, open-label, randomized controlled study evaluating the cost-effectiveness of a CCTA+CTP strategy versus usual care in intermediate to high risk patients with suspected or known CAD who undergo clinically indicated diagnostic evaluation.

Patients will be screened for study eligibility. Patients meeting all selection criteria will be asked to sign an informed consent document prior to undergoing any study-specific evaluation; then a structured interview will be performed and a clinical history obtained, assessing the presence of common cardiac risk factors, drug therapy (focus on statin, aspirin and/or antiplatelet agent use) and symptoms (typical or atypical angina, to estimate the pre-test likelihood of CAD).

Upon completion of the screening procedure and enrollment, the patients will be randomized 1:1 to the CT-based strategy (Group A) or usual care (Group B). Patient follow-up will be performed at 1 year (± 1 month) and 2 years (± 1 month) by trained interviewers who check medical records or by phone interview collecting the following information: downstream testing; overall radiation exposure; outcomes; cost-effectiveness estimation.

The primary endpoint of the study is the reclassification rate of CCTA in group B due to the addition of CTP. The secondary endpoint will be the comparison between group A and group B in terms of non-invasive and invasive downstream testing, prevalence of obstructive CAD at ICA, revascularization, cumulative ED and overall cost during the follow-up at 1- and 2-years. The tertiary endpoint will be the comparison between each group in terms of MACE and cost-effectiveness at 1- and 2-years.

Inclusion criteria

• Consecutive patients (age ≥ 18 years) with known or suspected CAD referred for clinically indicated diagnostic evaluation.
• CCTA has to be performed with the state of art in terms of scanner technology as follow: Revolution CT (GE Healthcare, Milwaukee, WI), CardioGraphe (Arineta, Caesarea, Israel), SOMATOM Force (Siemens, Forchheim, Germany), Brilliance iCT and IQon CT (Philips, Best, Netherlands), Aquilion One Vision (Toshiba Medical Systems Corp., Otawara, Japan).

Exclusion criteria

• Performance of any non-invasive diagnostic testing within 90 days before enrollment
• Low to intermediate pre-test likelihood of CAD according to the updated Diamond-Forrester risk model score
• Acute coronary syndrome
• Need for an emergent procedure
• Evidence of clinical instability
• Contra-indication to contrast agent administration and/or impaired renal function
• Inability to sustain a breath hold
• Pregnancy
• Cardiac arrhythmias
• Presence of pace maker or implantable cardioverter defibrillator
• Contra-indications to the administration of sub-lingual nitrates, beta-blockade and adenosine
• Structural cardiomyopathy outside of suspected or know ischemic heart disease