The Computed Tomography-derived Fractional Flow Reserve STAT Trial

Computed Tomography-derived Fractional Flow Reserve in the Systematic Triage of Emergency Department Acute Chest Pain Patients to Treatment. (The CTFFR-STAT Trial)

This study is designed to directly compare Standard Care and CT fractional flow reserve (CTFFR) for diagnosis of chest pain patients with definite coronary artery disease (CAD) on heart computed tomography (CT) scans.

New or worsening chest discomfort is the most common symptom of coronary artery disease (CAD), which is plaque build-up in the arteries that supply the heart muscle with blood. Chest pain is one of the most common reasons for emergency department (ED) visits, with an estimated 8 million new cases every year. Evaluation of chest pain is expensive and time consuming, even though 75% of the time it is not due to CAD. It is necessary to carefully define the amount of CAD, even if initial tests reveal no heart attack, because this symptom may progress to heart attack and death if missed.

Coronary artery computed tomography angiography of the heart (CCTA) is one of the most sensitive tests to detect serious CAD in appropriately selected patients.In 85% of acute chest pain (ACP) ED cases tested by CCTA, no CAD or very mild CAD is found, leading to rapid discharge or an alternative diagnosis. However, in the 15% of patients with significant CAD found on CCTA, further evaluation with either stress testing or heart catheterization, and/or hospital admission is required. Since 2015, Beaumont Health hospitals have employed a new FDA-approved test, called CT fractional flow reserve (CTFFR), that can analyze flow down the heart arteries by computer analysis of the original CT images. Results from an analysis of 147 patients suggest that 67% of the time, CTFFR showed no significant flow limitation, providing for the potential to defer invasive testing or treatment for a trial of medical therapy.

The use of CTFFR on ED patients is novel, and it is not yet part of the standard of care (SOC). Standard care of patients with definite CAD on CCTA continues to be hospital admission, stress testing and/or heart catheterization for further diagnosis. Both CTFFR and standard care continue to be used at Beaumont Health, and it is important to determine if one or the other diagnostic strategy is superior. This study is designed to directly compare standard care and CTFFR for diagnosis and management of ACP patients with definite CAD on CCTA.

Inclusion Criteria:

• Emergency department chest pain suspicious for ACS based on history and physical examination.
• At least one biomarker (troponin) and electrocardiogram with no evidence of definite ACS.
• A completed CCTA demonstrating >50% but <90% stenosis of at least one coronary artery branch.
• CCTA test images with sufficient diagnostic quality for CTFFR analysis.
• Ability and willingness to provide informed consent.

Exclusion Criteria:

• Left main coronary stenosis of 50% or greater.
• CCTA lesions demonstrating stenosis >90% ("subtotal"), or complex, high-risk plaque characteristics resulting in an a priori recommendation for triage to CATH by the CCTA interpreting physician.
• Attending physician a priori decision for CATH.
• Previous coronary stent, coronary bypass or prior known myocardial infarction.
• Clinical instability, such as hypotension, signs of shock, and/or accelerating chest pain requiring admission.
• Pregnancy