10.1 Invasive vs. Noninvasive Coronary Lesion Physiology: Who Should Get What and in Which Settings

These proceedings summarize the educational activity of the 17th Biennial Meeting of the International Andreas Gruentzig Society held January 30 to February 2, 2024 in Chiang Rai, Thailand.

Faculty Disclosures     Vendor Acknowledgments

2024 IAGS Summary Document

Statement of the problem or issue

Noninvasive coronary physiology based on CT-FFR (computed tomography fractional flow reserve) has much to recommend it. However, the value proposition of it is still evolving. It may have the potential to offer some efficiencies in the way we use invasive services, since it is a non-invasive imaging modality that can give us both anatomic and physiologic information. The PRECISE trial tested the hypothesis of whether CT-FFR, combined with risk stratification (that is, a clinical risk tool), could substitute for our traditional approach to non-invasive evaluation of patients with stable coronary disease.^1,2 It turned out there were benefits seen with this PRECISE, or rather, PRECISION strategy. The greatest benefit was in reducing invasive services in patients who turned out to have mild or no coronary disease that needed treatment beyond medical therapies. There is also a similar, related analytic process that uses standard angiograms coupled with proprietary software to reconstruct the vessel and its territory, and then apply fluid dynamics equations to calculate another parameter called the Quantitative Flow Ratio (QFR).^3,4 The QFR may discriminate between significant and nonsignificant coronary lesions, similar to FFR.

Gaps in current knowledge

The most compelling thing about CT-FFR, although still unproven, may be in the ability to use our cath labs more efficiently. In the PRECISE trial, patients in the standard care arm underwent evaluations, and ultimately 17% required coronary angiograms. In the precision care arm, with CT-FFR employed, only 13% required angiograms. But, importantly, a higher proportion of patients in the precision care arm required revascularization with PCI compared to the standard care arm (7.3% vs 3.5%), since the CT-FFR testing helped eliminate those patients unlikely to have obstructive coronary disease. Based on the financial estimates, there was approximately 20% more revenue per 100 patients undergoing coronary angiograms in the precision group compared to the standard care group. Therefore, the hypothesis is that the more accurate screening in the precision arm might make cath labs more efficient.

Possible solutions and future directions

Both of these methodologies, CT-FFR and QFR, will undergo rigorous testing and examination in the next few years. Clinical outcomes data demonstrating superiority for either of them over and above current practices have not yet been accumulated. The value proposition also still needs to be proven or refuted: Do either of these technologies make our invasive cath labs more operationally efficient?

References

1. Douglas PS, Nanna MG, Kelsey MD, et al. Comparison of an initial risk-based testing strategy vs usual testing in stable symptomatic patients with suspected coronary artery disease: The PRECISE randomized clinical trial. JAMA Cardiol. 2023;8(10):904-914. doi: 10.1001/jamacardio.2023.2595. PMID: 37610731.
2. Udelson JE, Kelsey MD, Nanna MG, et al. Deferred testing in stable outpatients with suspected coronary artery disease: A prespecified secondary analysis of the PRECISE randomized clinical trial. JAMA Cardiol. 2023;8(10):915-924. doi: 10.1001/jamacardio.2023.2614. PMID: 37610768.
3. Tu S, Westra J, Adjedj J, et al. Fractional flow reserve in clinical practice: from wire-based invasive measurement to image-based computation. Eur Heart J. 2020;41(34):3271-3279. doi: 10.1093/eurheartj/ehz918. PMID: 31886479.
4. Kanno Y, Hoshino M, Hamaya R, et al. Functional classification discordance in intermediate coronary stenoses between fractional flow reserve and angiography-based quantitative flow ratio. Open Heart. 2020;7(1):e001179. doi: 10.1136/openhrt-2019-001179. PMID: 32076563.