The Qianjiang International Cardiovascular Conference 2020 (QICC 2020) brought together leading cardiovascular experts across China on Aug. 31 to exchange views and discuss progress on the diagnosis and treatment of cardiovascular diseases. During the coronary heart disease sub-forum, Dr. Xinyang Hu of the Second Affiliated Hospital of Zhejiang University School of Medicine, delivered a special lecture on the “Clinical Significance and Research Progress of Non-invasive FFR.” During the presentation, Dr. Hu discussed non-invasive coronary artery functional assessment technology, including the diagnostic efficacy of the products, and how the clinical value of fractional flow reserve (FFR) are extracted and presented to clinicians.

The Necessity of CT-FFR

Coronary heart disease is an ischemic heart disease caused by atherosclerotic lesions in the coronary arteries. The mortality rate accounts for 10% to 20% of all cardiovascular deaths. Since the development of coronary heart disease will directly lead to myocardial ischemia and acute cardiovascular events, early judgement and effective intervention of the degree of vascular stenosis and myocardial ischemia caused by coronary atherosclerotic plaque are crucial.

Currently, non-invasive coronary CT angiography (CTA) is one of the primary methods used for coronary heart disease screening and review. Coronary CTA examination uses ≥50% stenosis as the standard for epicardial artery obstructive stenosis. However, with the extensive application of coronary interventional diagnosis and treatment and the development of a number of clinical studies, it has been found that there are inconsistencies in the anatomical and functional assessments. The stenosis shown by coronary CTA images alone cannot be used as a reference standard to assess whether the presence of myocardial ischemia in the coronary will lead to unnecessary coronary angiography (ICA) examinations and coronary interventions (PCI) for patients with positive initial screening, which will not only increase the patient’s medical risk and economic burden, but also cause medical resources waste.

FFR has gradually become the “gold standard” for functional evaluation of invasive lesions since DEFER, FAME I, and FAME II, and FFR-guided treatment strategies can effectively evaluate functional myocardial ischemia and improve patient prognosis. However, FFR is an invasive interventional diagnostic technology. Common pain points for using FFR include that it is a time-consuming and inconvenient operation, it is costly, and there can be vasodilator-related reactions. On a global scale, the clinical application of FFR is not ideal. The penetration rate of invasive FFR in China is less than 1%.

Non-invasive FFR Calculation

With the rapid advancement of computer simulation computing technology and artificial intelligence technology in recent years, the early diagnosis of coronary artery disease has been continuously improved.

Non-invasive CT-FFR technology based on coronary CTA combines the advantages of CTA and FFR, and reconstructs blood vessel images with high precision through CT images, thereby calculating FFR values ​​around the blood vessels, and evaluating the coronary arteries from two aspects of blood vessel structure and function. The degree of stenosis can be determined before coronary angiography for patients who cannot benefit from interventional therapy (PCI) but only need medical treatment (FFR negative), reducing unnecessary coronary angiography and avoiding unnecessary risks and costs.

The Diagnostic Power of CT-FFR

There are currently a number of prospective multi-center clinical studies in the world using coronary CTA and FFR as reference standards to study the diagnostic accuracy of CT-FFR. The DISCOVER-FLOW study has verified that CT-FFR has a good correlation with invasive FFR, and does not require additional imaging examinations or medications, which can help to effectively reduce unnecessary coronary angiography and revascularization treatments.

The PACIFIC study demonstrates that CT-FFR has the largest Area Under the Curve (AUC) among multiple non-invasive coronary evaluation methods, which not only makes up for the lack of accuracy, specificity, and positive predictive value of CTA, but also reduces the medical cost of patients undergoing invasive examination.

Another meta analysis recently published by the team of Professor Minjie Lu from Fuwai Hospital of the Chinese Academy of Medical Sciences showed that CT-FFR can significantly improve the effect of CT-FFR on myocardial ischemia, regardless of the patient level or the vascular level. The specificity of diagnosis reduces the rate of misdiagnosis.

In addition, through the summary of a large number of clinical case data, on the basis of coronary CTA, CT-FFR combined with imaging plaque characteristics can improve the accuracy of coronary CTA results and have better diagnostic value. For the same lesion, in the calculation process of CT-FFR, the CT-FFR value calculated by including the peripheral branch is closer to the true value than without the peripheral branch (0.77 vs. 0.81), and the accuracy is relatively improved.

Clinical Applications

After a number of large-scale international multi-center clinical trials, the clinical application of CT-FFR can avoid more than 61% of “non-essential” coronary angiography examinations, improve patient treatment paths, save overall medical costs, and compare with invasive angiography In comparison, the clinical prognostic outcome is better and has a good development prospect.
CT-FFR technology also holds potential in assisting decision-making. In clinical applications, it has been confirmed that “virtual stent placement” based on CT-FFR measurement can assist in planning the optimal treatment strategy and predicting functional outcomes. In addition, when compared with the evaluation of luminal stenosis based on CT, CT-FFR can significantly improve the diagnostic ability of coronary CTA for different degrees of calcification, and has better diagnostic value.
The emergence of CT-FFR for diagnosis and treatment provides a new pathway for non-invasive detection of functional ischemia assessment, such that more patients with non-obstructive coronary heart disease can avoid entering the catheterization laboratory for invasive procedures. At the same time, it assists doctors in efficiently diagnosing coronary heart disease, screening people who really benefit from interventional therapy, and formulating personalized diagnosis and treatment plans to reduce patient medical risks and save medical costs.

New Technology: DEEPVESSEL FFR

DEEPVESSEL FFR, the first Class III medical device in China to obtain regulatory approval from the National Medical Products Administration, uses AI to non-invasively evaluate the physiological function of the coronary arteries using coronary CTA scans. It can efficiently and accurately calculate the FFR value at each point on the entire vascular tree structure, and quickly provide the clinically required quantitative test results.

The structure-based analysis of traditional CTA is highly sensitive to distinguish coronary artery lesions, but has a low specificity and high false-positive rate. DEEPVESSEL FFR can reduce the false positive rate, and has demonstrated to improve accuracy, specificity, positive predictive value, and negative predictive value. It provides an effective non-invasive method for clinically determining whether there is functional myocardial ischemia.

By providing clinical quantitative evaluation indicators before invasive coronary angiography, DEEPVESSEL FFR helps doctors formulate treatment plans for individual patients, effectively reducing unnecessary costs from coronary angiography examinations and the use of pressure guide wires, as well as reducing the high cost of treatment.

The prevention and treatment of cardiovascular disease has a long way to go. Keya Medical is committed to reducing medical expenses and improving quality of life through better access to diagnostics.