1. Introduction and Study Rationale This study focuses on developing and validating an innovative technology called IVUS-derived Fractional Flow Reserve (IVUS-FFR), which aims to address limitations in current methods for assessing coronary artery stenosis. Coronary artery disease often requires precise evaluation of blood flow restrictions to determine if interventions like stents are necessary. The gold standard, Fractional Flow Reserve (FFR), involves invasive pressure wires and vasodilator drugs (e.g., adenosine), leading to increased costs, procedural time, and potential complications such as allergic reactions or hemodynamic instability. By contrast, IVUS-FFR integrates intravascular ultrasound imaging with computational fluid dynamics to estimate functional significance without additional devices or medications. This approach could streamline clinical workflows, reduce patient discomfort, and lower healthcare expenses, making it a promising advancement in cardiovascular diagnostics.
2. Primary Research Objectives The core goal is to evaluate the diagnostic accuracy of the IVUS-FFR system in identifying hemodynamically significant coronary stenosis, defined as a reduction in blood flow warranting intervention. Using a prospective, multicenter design, the study directly compares IVUS-FFR against FFR as the reference standard. Secondary objectives include assessing feasibility in real-time catheterization lab settings, establishing standardized operational protocols, and refining the technology for broader clinical adoption. Additionally, the study will contrast IVUS-FFR with quantitative coronary angiography (QCA), an anatomical assessment tool, to demonstrate superior diagnostic performance in detecting functionally relevant lesions.
3. Study Design and Methodology Overview This research employs a prospective, multicenter, self-controlled clinical trial framework. It targets enrollment of 292 adult participants with suspected or confirmed coronary artery disease, specifically those exhibiting at least one visually estimated coronary stenosis between 30% and 90% diameter reduction. Participants undergo sequential assessments: first, standard coronary angiography and IVUS imaging to generate detailed vascular reconstructions; second, immediate online IVUS-FFR analysis using proprietary algorithms; and third, conventional FFR measurement for validation. Blinding protocols ensure objectivity-IVUS-FFR operators are unaware of FFR results during analysis, and an independent core lab processes QCA data. Statistical methods include receiver operating characteristic (ROC) curves to calculate area under the curve (AUC), sensitivity and specificity analyses, and Delong tests for comparing IVUS-FFR and QCA performance. The sample size provides 90% statistical power to detect a target diagnostic accuracy of 83% for IVUS-FFR.
4. Technological Innovations and Workflow Integration The IVUS-FFR system represents a significant leap in computational physiology. It combines high-frequency intravascular ultrasound (40MHz probes) with artificial intelligence-driven segmentation. This involves deep neural networks to automatically delineate vessel structures, such as the lumen and external elastic lamina, enabling precise 3D vascular modeling. Blood flow simulations leverage Murray's law for adaptive hemodynamic calculations, ensuring accurate pressure drop estimations across stenoses. Key innovations include real-time processing capabilities-results are generated within 90 seconds of IVUS data acquisition-and compatibility with existing catheterization lab equipment. This integration minimizes workflow disruptions, adding less than 10 minutes to standard procedures while eliminating the need for pressure wires or vasodilators.
5. Participant Eligibility and Ethical Safeguards Eligible participants are adults aged 18 years or older with coronary artery disease symptoms, such as stable or unstable angina, who are scheduled for diagnostic angiography. Exclusion criteria prioritize safety, excluding individuals with recent myocardial infarction (within 72 hours), severe heart failure, significant kidney impairment, pregnancy, or contraindications to iodinated contrast agents. All participants provide informed consent, and the study adheres to stringent ethical oversight through Fuwai Hospital's institutional review board. Rigorous risk mitigation strategies include protocolized management of potential complications like vessel injury during IVUS catheterization and on-site emergency resources for adenosine-related adverse events.
6. Expected Outcomes and Broader Implications Upon completion, the study aims to validate IVUS-FFR as a non-inferior alternative to FFR, with anticipated diagnostic accuracy exceeding 83%. This could establish new clinical standards, reducing reliance on invasive FFR and cutting procedural costs by approximately $850 per case. Broader impacts include intellectual property development, such as 2-3 national patents for the core algorithms and 1-2 software copyrights. Dissemination will occur through high-impact publications in Q1-ranked journals and presentations at international conferences, potentially influencing future guidelines on coronary revascularization. If successful, IVUS-FFR could extend to peripheral vascular applications, enhancing patient outcomes globally by enabling faster, safer, and more accessible functional assessments.
