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TCTAP 2024

FFR and iFR: Where Do We Stand Today?

Reassessment of Coronary Artery Disease Diagnostics: FFR Reigns Supreme Nico Pijls, MD Catharina Hospital, Netherlands In the evolving landscape of cardiology, the debate over the most reliable method for assessing coronary artery disease has reached a crucial juncture. Fractional Flow Reserve (FFR) and Instantaneous Wave-free Ratio (iFR) have both been subjects of intense scrutiny and discussion. However, recent insights, especially new recommendations from leading cardiology journals and associations, are reaffirming FFR as the gold standard for assessing coronary artery disease. Understanding FFR and iFR FFR is an index that measures the maximum achievable blood flow in the presence of a coronary stenosis compared to normal maximum flow. The underlying principles of FFR are rooted in sound physiology. It evaluates the functional capacity of a patient's heart under maximum vasodilation, correlating to exercise tolerance. This method has significantly influenced decision-making in catheterization labs, aiding in precise revascularization strategies and improving patient outcomes. However, FFR measurement necessitates a pharmacological hyperemic stimulus, typically involving adenosine or ATP infusion. Although these agents have transient side effects, the benefits of accurate measurement outweigh the minor inconveniences. In contrast, iFR emerged as a simpler alternative to FFR. Proposed by Davies et al., iFR measures the resting Pd/Pa ratio during a specific part of diastole, eliminating the need for a hyperemic stimulus. Initial enthusiasm for iFR was bolstered by two large randomized controlled trials (DEFINE-FLAIR and SWEDE-HEART), which suggested non-inferiority of iFR compared to FFR. Critical Analysis of iFR Despite the initial optimism, several concerns about iFR have come to light. The concept of a “wave-free period” during diastole lacks a solid physiological basis, and predicting hyperemic gradients from resting gradients has proven unreliable. Furthermore, serious design and interpretation issues in the DEFINE-FLAIR and SWEDE-HEART studies have raised questions about their validity. Notably, these studies involved low-risk populations, with a significant proportion of patients not undergoing PCI and many stents placed without physiological measurements. Biases in the study designs were particularly problematic. For example, almost 50% of stents were placed based on visual lesion severity rather than physiological measurement. Many false-negative iFR results were excluded from the analysis, skewing the data to appear more favorable. This bias went largely unrecognized by investigators, leading journals, and guideline committees. Long-term follow-ups revealed troubling outcomes. Mortality rates in the iFR-guided groups were significantly higher than those in FFR-guided groups, a disparity that increased over time. These findings have prompted a reassessment of iFR's reliability, especially in high-stakes clinical decisions. New Recommendations In response to these revelations, the Journal of the American College of Cardiology (JACC) and the European Heart Journal (EHJ) now recommend FFR as the preferred method for assessing proximal lesions in large coronary arteries. Upcoming guidelines are expected to reflect this preference, emphasizing FFR-guided revascularization as the standard for intracoronary pressure measurement. The cardiology community's initial enthusiasm for iFR and other non-hyperemic pressure ratios has been tempered by emerging evidence of their limitations. The biases and higher mortality rates observed in key studies underscore the necessity of relying on methods with a robust physiological basis. As such, FFR remains the gold standard, ensuring precise diagnostics and optimal patient outcomes in coronary artery disease management. Hot Topics Coronary Physiology: New Insights Friday, April 26, 3:30 PM ~ 5:44 PM Presentation Room 2, Level 1 Check The Session

June 19, 2024 3013

TCTAP 2024

Who Will Treat the Most Complex Patients? No Success Goes Unpunished.

During TCTAP 2024, live cases, and lecture 6, the discussion revolved around the treatment of the most complex patient cases. Spencer B. King, MD (Emory Healthcare, USA), shared insights into the evolving role of percutaneous coronary intervention (PCI) compared to surgery in such cases. In his introductory remarks, he emphasized the shifting landscape of PCI being increasingly favored over surgery, particularly in treating left main (LM) shaft disease. Significant contributions by Seung-Jung Park, MD (Asan Medical Center, Korea) were highlighted in this paradigm shift. Previously, interventionists would often opt for surgery when confronted with challenging cases. However, He noted a trend toward choosing PCI, citing highly sophisticated PCI skills as a driving factor. An illustrative case discussed was that of an 85-year-old male patient with a history of acute coronary syndrome (ACS), recurrent chest pain, and heart failure (Figure 1). The patient presented with multiple risk factors including diabetes, chronic renal failure, cerebrovascular accident, peripheral artery disease, and severe chronic obstructive pulmonary disease. The electrocardiogram confirmed LM disease consistent with ACS. Figure 1. One most complex patient case Initial coronary angiography revealed LM plus triple-vessel disease with complex lesions, including LM trifurcation disease and heavily calcified, diffuse long left anterior descending artery disease, alongside total occlusion of the proximal right coronary artery. Given the patient's profile, both coronary artery bypass surgery (CABG) and PCI were considered. However, CABG was deemed prohibitive due to technical challenges, and the patient's advanced age and comorbidities. PCI posed its own difficulties, including the complexity of LM trifurcation lesions, the need for debulking procedures such as rotablation, and potential requirement for mechanical circulatory support. Assessing the postoperative outcomes, surgical mortality rates were projected to be high, prompting a thorough evaluation of the risks associated with both procedures. Ultimately, PCI was chosen for this high-risk patient, with successful completion reported. He highlighted the lack of randomized controlled trials focusing on PCI for such complex cases. Instead, he referenced a recent registry study involving over 700 patients who were turned down for surgery and underwent PCI at specialized centers. The study showed that there was no difference in the actual mortality rate compared to the mortality rate predicted by the Society of Thoracic Surgeons score and EuroScore II, and that the symptoms of the patients improved 6 months after PCI compared to the baseline condition (Figure 2). Figure 2. Improvement in patient symptoms 6 months after PCI compared to baseline condition Looking ahead, he emphasized the need for further research to validate these findings and address key questions surrounding the selection of treatment modalities for complex cases. He advocated the establishment of local registries for high-risk patients to inform clinical decision-making. In concluding the lecture, he left a lasting message for interventional cardiologists that no spectacular success will go unpunished and the more tough cases you take, the more you will get, which may be a good thing. As the field continues to evolve, the quest for optimal treatment strategies for the most complex patients remains ongoing. Live Case & Lecture 6: Complex PCI Friday, April 26, 3:30 PM ~ 5:00 PM Main Arena, Level 2 Check The Session

June 19, 2024 2009

TCTAP 2024

Provisional Stenting in Left Main vs. Non-Left Main Complex Bifurcation Stenoses: Is There a Differe...

Scott Harding, MD (Wellington Hospital, New Zealand), was the first presenter in the ‘New concept of Bifurcation PCI’ session, highlighting the unique characteristics of the left main bifurcation compared to other bifurcations (Figure 1). The Left main bifurcation is a larger vessel with crucial branches in almost all cases. Notably, the bifurcation angle (B angle) is generally larger, and there is more calcification and fibrosis, particularly at the circumflex ostium. Additionally, the geometry of the left main bifurcation differs significantly from other bifurcations, such as the left anterior descending (LAD) bifurcation. Figure 1. Unique characteristics of Left main bifurcation Importance of the Circumflex and Myocardial Subtension He stressed the importance of the circumflex artery, which supplies more than 10% of the myocardium in 90% of cases. In contrast, only 20% of the non-left main bifurcations supply a similar amount of myocardium. It was noted that CT estimates might overstate these figures, suggesting that the actual numbers could be lower. He emphasized the critical need to avoid leaving significant disease untreated in the circumflex, citing high event rates over 5 years for patients with low fractional flow reserve (FFR) who did not receive intervention. Clinical Outcomes: Left Main vs. Non-Left Main Bifurcations Drawing from various registries, including the Coronary Bifurcation Stent III Registry from Korea, he illustrated that left main bifurcation interventions typically result in worse outcomes compared to non-left main bifurcations. This discrepancy is likely due to the larger area of jeopardized myocardium in Left main cases. The complexity of the disease also significantly impacts outcomes, underscoring the importance of comprehensive treatment strategies. Optimal Stenting Strategies He discussed findings from several trials, including the DKCRUSH-V and EBC MAIN trials, which suggest that complex Left main bifurcations benefit more from a two-stent strategy than a provisional strategy. The DKCRUSH-V trial showed a significant reduction in target lesion revascularization with a two-stent approach, especially in complex lesions (Figure 2). Conversely, the EBC Main trial found a provisional approach to be non-inferior in less complex diseases. These results highlight the necessity of tailoring stenting strategies to the complexity of the lesion. Figure 2. Benefits of two-stent strategy from DKCRUSH-V trial Unintentional Stent Deformation: Insights from the OCTOBER Trial An important point from his lecture was the issue of unintentional stent deformation, revealed in the OCTOBER trial. The trial found that 9% of cases experienced unintended stent deformation, with this rate increasing to 19% in left main bifurcations. Factors contributing to this complication include guide catheter collision and abluminal wiring, particularly in complex left main procedures (Figure 3). This finding underscores the need for meticulous attention during stent placement. Figure 3. Mechanisms and outcomes of unintentional stent deformation He concluded by reiterating the differences and challenges associated with left main bifurcation interventions. He noted that the worse outcomes often seen in these cases reflect the large amount of jeopardized myocardium. While a provisional stenting strategy can be effective for most non-left main bifurcations, an upfront two-stent strategy is often warranted for complex left main lesions. These decisions should be guided by the specific characteristics and complexity of the disease. TCTAP Workshops New Concept of Bifurcation PCI Thursday, April 25, 4:00 PM ~ 5:40 PM Valve & Endovascular Theater, Level 2 Check The Session

June 19, 2024 1895

TCTAP 2024

Don't Forget About Dual Pathway Inhibition: When DOAC Should NOT Be Standard Treatment

Dominick J. Angiolillo, MD (University of Florida College of Medicine, USA), recently delivered a compelling lecture on the nuances and critical considerations surrounding dual pathway inhibition (DPI). The presentation started by introducing basic concepts of thrombosis formation (Figure 1). In case of an atherosclerotic plaque rupture, two key pathways are activated; the cellular pathway represented by platelets, as well as the plasma component represented by thrombin. The surface of the activated platelets is the main source for generation of thrombin, indicating an interplay between the two mechanisms. Despite efforts to block platelet activation, thrombosis continues to occur, leading to the concept of DPI of both platelets and coagulation. Figure 1. Mechanism of thrombus formation Ischemic events continue to occur even during aspirin monotherapy, and there have been some disappointments with the strategies of using alternative antiplatelet therapies. This led to a question of whether a very low-dose rivaroxaban (2.5 mg bid) in adjunct to aspirin can reduce ischemic events, which was tested in the COMPASS trial (Figure 2). The landmark COMPASS trial examined nearly 30,000 patients to determine the efficacy of adding low-dose rivaroxaban to aspirin therapy. Results from this trial indicated a significant decrease in ischemic events when using the combined DPI strategy versus aspirin alone, reshaping long-term secondary prevention tactics for patients with stable coronary and peripheral artery disease (CAD and PAD). Figure 2. Primary Endpoint of the COMPASS trial Despite these promising outcomes, the inherent risks associated with DPI were also addressed, which is an increased incidence of major bleeding events (Figure 3). This aspect remains a crucial consideration in clinical decision-making, emphasizing the need for careful patient selection based on individual risk profiles. Figure 3. Bleeding Outcomes from the COMPASS trial Studies on intensified antithrombotic therapy for long-term secondary prevention in patients with chronic coronary syndrome were highlighted (Figure 4), and the lecture concluded with a detailed algorithm to aid physicians in selecting the appropriate therapeutic strategy, considering factors such as high-risk features of both bleeding and ischemic events, including multivessel coronary disease, chronic kidney disease, diabetes, recurrent myocardial infarctions, and history of prior ischemic stroke (Figure 5). Figure 4. Studies on intensified antithrombotic therapy for long-term secondary prevention in CCS Figure 5. Algorithm for the choice of antithrombotic therapy in CCS patients Hot Topics All About New Data of Antithrombotics Friday, April 26, 4:40 PM ~ 6:06 PM Presentation Room 1, Level 1 Check The Session

June 19, 2024 1859

TCTAP 2024

Bicuspid TAVR: All the Technical Issues and Data from Asan Medical Center

Jung-Min Ahn, MD, PhD (Asan Medical Center, Korea), presented a comprehensive overview of the technical challenges and clinical outcomes associated with transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic stenosis (AS) from Asan Medical Center. He highlighted the clinical and anatomical challenges of treating bicuspid AS with TAVR, emphasizing that clinical evidence is still limited. He referenced a large dataset of 12,000 patients, comparing outcomes between bicuspid and tricuspid aortic valve TAVR. The data showed no significant differences in hard endpoints, though bicuspid TAVR was associated with an increased risk of paravalvular leak (PVL) and aortic root injury. One key discussion point was comparing TAVR and surgical aortic valve replacement (SAVR) in bicuspid aortic valve stenosis. While some studies showed no difference in mortality, others suggested numerically higher risk with SAVR, though this was not statistically significant (Figure 1). Device-specific outcomes were also discussed, noting that self-expandable devices had a higher risk of moderate or significant PVL, whereas balloon-expandable devices were associated with a higher risk of annulus rupture and aortic root injury. Figure 1. Comparison of TAVR and SAVR in bicuspid AS He emphasized the importance of calcification in bicuspid valves. These valves often have a higher amount of calcium compared to tricuspid valves, which may lead to higher procedural risks. It was also pointed out that younger patients typically have a higher incidence of bicuspid AS, while it’s not as common in older age groups. The presentation also included data on device sizing. Most bicuspid valves fall into tubular and flare types, which allow for device sizing based on annular size in 90% of cases. He primarily focused on the Sapien 3 device, noting its effectiveness when sized correctly. He stressed the importance of avoiding oversizing in cases of severe calcification to reduce the risk of complications (Figure 2). Figure 2. Importance of avoiding oversizing in cases of severe calcification He concluded that bicuspid AS has distinct clinical and phenotypical characteristics, such as younger patient age, more severe aortic valve calcification, and associated aortopathy. The incidence of paravalvular leak is higher compared to tricuspid aortic valve cohorts undergoing TAVR, and caution should be exercised regarding aortic injury. Despite these challenges, TAVR for bicuspid AS is not associated with an excess risk of mortality and stroke. Sapien 3 implantation in bicuspid aortic valves is comparable to its use in tricuspid valves. Therefore, there is a need to define specific criteria for selecting patients with bicuspid aortic stenosis who can be successfully treated with TAVR, much like the Echo-Score for rheumatic mitral stenosis. Hot Topics TAVR: Future Perspectives Saturday, April 27, 9:00 AM ~ 10:34 AM Valve & Endovascular Theater, Level 2 Check The Session

June 19, 2024 1822

TCTAP 2024

The Series of FAME Studies: A Paradigm Shift in Our Thinking About Interventional Cardiology

William F. Fearon, MD Stanford University, USA Coronary artery disease (CAD) management has significantly evolved over the past decade, largely due to the pivotal findings from the Fractional Flow Reserve versus Angiography for Multivessel Evaluation (FAME) trials. The FAME 1, FAME 2, and FAME 3 studies collectively underscored the transformative role of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) in optimizing treatment strategies for patients with CAD. Published in 2009, the FAME 1 trial, laid the groundwork for using FFR in guiding PCI. Traditionally, angiography has been the cornerstone for identifying significant coronary stenoses. However, the FAME 1 trial demonstrated that incorporating FFR measurements during PCI significantly improved patient outcomes. The study included 1,005 patients with multivessel CAD. It revealed that FFR-guided PCI, compared to angiography alone, resulted in a lower incidence of major adverse cardiac events (MACE) over 1 year (13.2% vs. 18.3%, p=0.02). FAME 1 established that physiology-guided PCI simplifies the treatment process and enhances the prognostic outcomes for patients undergoing multivessel PCI. The FAME 2 trial, published in 2014, further validated the importance of FFR in patients with stable CAD. De Bruyne and colleagues conducted a study involving 1,220 patients, comparing outcomes between those who received FFR-guided PCI and those managed with medical therapy alone. The results showed patients in the FFR-guided PCI group had a significantly lower rate of the primary composite endpoint of death, myocardial infarction (MI), or urgent revascularization compared to the medical therapy group (4.3% vs. 12.7%, p

June 12, 2024 1009

TCTAP 2024

Calcified Nodules in Complex PCI: Are They All the Same and How Should We Treat?

Akiko Maehara, MD (Cardiovascular Research Foundation, USA), started the lecture with a question, "What kind of calcified plaque should be treated?". The OCT study that was introduced enrolled 272 calcified nodules (CNs) in 230 patients who underwent pre- and post-optical coherence tomography (OCT). Nodules were divided into 2 groups, which were eruptive and non-eruptive CNs. In this study, the prevalence of CN was 5.9% per vessel and 7.3% per patient (Figure 1). Figure 1. OCT trial design Explosive Calcified Nodules (CNs): Predictors of Better Stent Expansion but Worse Post-PCI Outcomes She stated that eruptive CNs are one of the predictors of better stent expansion because of the re-distribution mechanism of plaques. However, eruptive CNs showed a worse post-percutaneous coronary intervention (PCI) outcome in terms of target lesion failure (TLF) compared to non-eruptive CNs (Figure 2). Factors associated with 2-year TLF included eruptive CNs, the circumference of the CN, angle in lesions, and the stent area. The lecture concluded with the following messages, 1) Stent implantation deformed an eruptive CN more than a noneruptive CN 2) Non-eruptive CN, greater CN, greater surrounding calcium, and negative remodeling were associated with poor stent expansion 3) TLR increased at 6 months post-PCI in the eruptive CN group more than non-eruptive CN group 4) An eruptive CN, greater CN, greater hinge motion, and small stent area were associated with a worse 2-year TLF Figure 2. Outcomes pre- and post-PCI in eruptive and non-eruptive CNs Hot Topics All About Tips & Tricks for Complex PCI Saturday, April 27, 9:30 AM ~ 11:10 AM Main Arena, Level 2 Check The Session

June 12, 2024 916

TCTAP 2024

New Launched M-TEER Device for Degenerative Mitral Regurgitation: PASCAL Experiences in Japan

Shinichi Shirai, MD (Kokura Memorial Hospital, Japan), highlighted the advancements and clinical experiences with the PASCAL device for treating degenerative mitral regurgitation (MR) in Japan. He detailed the procedure using a case study of a 79-year-old woman with severe MR due to P2 prolapse. Despite her complex medical history, the team opted for the M-TEER procedure using the PASCAL system (Figure 1). Pre-procedure echocardiography showed significant regurgitation with an effective regurgitant orifice (ERO) of 0.76 cm². Figure 1. Final results of M-TEER procedure using the PASCAL system Advantages of the PASCAL system: Ergonomic Design and Ease of Use The ergonomic handle and ease of manipulation were highlighted, making the procedure smoother and potentially reducing the learning curve. He emphasized the system's guide sheath, which easily penetrated the septal portion, facilitating straightforward atrial navigation. PASCAL Clips: Tailored Solutions for Varied Anatomical Needs The PASCAL system offers two types of clips: PASCAL Ace and PASCAL, catering to different anatomical needs. The ergonomic design and streamlined structure make it user-friendly and effective in reducing left atrial pressure post-procedure, with no residual mitral stenosis and improved pulmonary vein flow. Early Clinical Experiences and Future Prospects of the PASCAL System in JAPAN He concluded the lecture by underscoring the numerous benefits of the PASCAL system, based on their initial experiences in Japan (Figure 2). Due to its seamless structure, the guide sheath was particularly effective in accessing and penetrating the septum. The PASCAL system's ergonomic handle allowed for precise manipulation during the procedure, which is crucial for successful outcomes. Although structural differences exist compared to preceding products, familiarity with treatment techniques may contribute to a faster learning curve for practitioners. Compared to the previous devices, the PASCAL system showed less mitral valve area loss due to its spacer, and the width of the paddle could potentially reduce the number of devices needed per procedure. Overall, the PASCAL system represents a significant advancement in the treatment of degenerative MR, offering enhanced patient outcomes and a promising future for mitral valve interventions in Japan and beyond. Figure 2. Conclusion from the Japanese experiences of using the PASCAL device Hot Topics Evolution of Mitral and Tricuspid Interventions Saturday, April 27, 10:40 AM ~ 11:52 AM Valve & Endovascular Theater, Level 2 Check The Session

June 12, 2024 719

TCTAP 2024

Following BEST-CLI and BASIL-2: How to “Best” Serve Critical Limb Threatening Ischemia?

Chronic limb-threatening ischemia (CLTI), a condition of arterial insufficiency of the lower limb with ischemic foot pain at rest, a nonhealing ischemic ulcer, or gangrene, is the most severe form of peripheral arterial disease, and its optimal initial treatment—whether it’s surgical or endovascular revascularization—remains a topic of debate. At TCTAP 2024, Lawrence A. Garcia, MD (St. Francis Hospital, USA), provided insights into this issue by analyzing details from two landmark trials, BEST-CLI and BASIL-2 (Figure 1). Published a year ago at around the same time, these studies presented contradictory conclusions about patients with CLTI, thus causing considerable debate. Figure 1. BEST-CLI vs. BASIL-2 Trial designs The BEST-CLI study was a randomized superiority trial that enrolled 1,847 patients across 150 sites in the USA, Canada, Finland, Italy, and New Zealand. It consisted of two cohorts: cohort 1 included 1,434 patients with suitable venous conduits for bypass (718 undergoing surgical revascularization and 716 receiving endovascular treatment), and cohort 2 included 396 patients requiring alternative conduits (197 undergoing surgical revascularization and 199 receiving endovascular treatment). In cohort 1, the median time to the index procedure was 4 days (interquartile range [IQR], 1-11 days) for the surgical group and 1 day (IQR, 0-7 days) for the endovascular group. In the surgical group, 85% of the procedures utilized a single segment of the great saphenous vein, achieving a technical success rate of 98%, compared to 85% in the endovascular group. In cohort 2, the median time to the index procedure was 4 days (IQR, 1-13 days) for the surgical group and 1 day (IQR, 0-7 days) for the endovascular group, with technical success rates of 100% and 80.6%, respectively. During a median follow-up of 2.7 years in cohort 1, 42.6% of the surgical group and 57.4% of the endovascular group experienced the primary outcome of major adverse limb events (MALE) or death (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.59-0.79; p< .001). The surgical group also had fewer major reinterventions and above-ankle amputations than the endovascular group (9.2% and 10.4% vs. 23.5% and 14.9%, respectively). In the BASIL-2 study, patients with CLTI requiring infrapopliteal revascularization who received the best endovascular treatment had better amputation-free survival (AFS) than those who received surgical vein bypass. Conducted across 41 hospital-based vascular surgery units in the United Kingdom, Sweden, and Denmark, the study had no exclusions for vein or bypass suitability and involved 345 patients. Major amputation or death occurred in 63% of patients (108 out of 172) in the vein bypass group versus 53% (92 out of 173) in the best endovascular treatment group (adjusted HR, 1.35; 95% CI, 1.02-1.80; p = .037). The median AFS was 3.3 years (IQR, 2.1-4.3 years) in the vein bypass group and 4.4 years (IQR, 3.4-5.9 years) in the best endovascular treatment group. Death from any cause occurred in 53% of the vein bypass group and 45% of the best endovascular treatment group (adjusted HR for overall survival, 1.37; 95% CI, 1.00-1.87). Major amputation occurred in 20% of the vein bypass group and 18% of the best endovascular treatment group (adjusted HR, 1.23; 95% CI, 0.75-2.01). “There are difficulties in conducting a trial involving the below-the-knee (BTK) arteries. Apart from the outcomes for the above-the-knee studies, which seem dependent upon patency and walking difficulties, the BTK data are mired in endpoints, heterogeneity of subjects, non-uniform nature of wound care, and type of patients enrolled.” he emphasized at the beginning of his lecture that these characteristics have been observed in endovascular studies involving BTK vessels, such as the IN.PACT DEEP, LEVENT, and SAVAL trials. Emphasizing the features of the trials, he mentioned that in the BEST-CLI study, only 18% of the enrollees were non-surgeons in the endovascular group, there was no interventional monitoring committee for those who did the intervention, and of the patients enrolled in the endovascular group, there was a 38% crossover that has never been defined. The primary endpoint was the composite of death and MALE. Of note, one component of MALE was a ‘major’ reintervention, which did not include restenosis. Reintervention need and timing were determined by the site investigator, and there were no clinically-driven target lesion revascularization criteria or independent adjudication. In BASIL 2, the MALE endpoints were similar in both treatment sides. Still, revision or primary procedural repeat as failure was assessed as an outcome, and any restenosis was considered a failure in the endovascular group. The primary endpoint was AFS or all-cause death. Of note, only mortality drove the difference between cohorts. His key message was that unfortunately, difficulties with patients, wounds, and endpoints have allowed no one trial to be successful and acceptable. “In a given trial, patients need to be very specific and unless they are, the results will not answer the question for the cohort we see every day with CLTI. Unfortunately, that must be our first step. In this environment, the two trials are remarkable studies that, unfortunately, missed their mark for the question asked.” he concluded. Hot Topics EVAR, TEVAR and Peripheral Interventions Saturday, April 27, 2:00 PM ~ 3:18 PM Valve & Endovascular Theater, Level 2 Check The Session

June 12, 2024 697

TCTAP 2024

AI Application of Cardiovascular Imaging

A recent lecture at TCTAP 2024 introduced a new database for developing cardiovascular imaging artificial intelligence (AI), integrating AI models for post-percutaneous coronary intervention (PCI) evaluation, and application of general AI. Jihoon Kweon, MD, PhD (Asan Medical Center, Korea), has developed AI-QCA, which provides reproducible and reliable real-time coronary angiography analysis. To achieve this, data from 10,000 patients were used to train the AI, minimizing exclusions better to reflect the characteristics of the real patient pool. However, the challenge of expanding the database size to develop a more robust AI model remained. To address this, he built a large-scale database (Asan Invasive Coronary Angiography Network, A-ICAnet) containing 3 million angiographic frames, with plans to increase this to 100 million images (Figure 1). He demonstrated that by using A-ICAnet, segmentation of target vessels could be improved by more than 2% on average. He also suggested that A-ICAnet could be used for segmenting lumens in other views or with different interventional devices. Figure 1. A large-scale coronary angiography database for AI development AI integration was then introduced to post-PCI stent evaluation. Although stent expansion can be evaluated by specifying the proximal and distal ends of the implanted stent using AI-QCA, eliminating manual operations will help incorporate post-PCI stent evaluation into clinical practice. He developed an AI model for stent segmentation in fluoroscopy to automatically set the reference points for post-PCI stent evaluation. Over 1,000 images were collected at Asan Medical Center and used for AI training. Using an ensemble of three segmentation models, the AI achieved an F1 score of over 88%. By mapping the stent area onto the angiography, the proximal and distal ends of the stent area could be determined accurately (Figure 2). Post-PCI evaluation using AI-QCA was completed within one second without additional image acquisition. In the representative case, the AI model accurately set the stent area for assessment and identified an under-expansion that would likely be difficult to estimate visually. Figure 2. AI-AI integration for post-PCI stent evaluation Lastly, he demonstrated the potential of general AI for cardiovascular imaging. Meta has developed an AI model called the Segment Anything Model (SAM), which segments each area based on user input. With SAM, a catheter or guidewire could be automatically segmented with just one click (Figure 3). Although this task previously required advanced image processing methods, it now requires a single AI model without labeling, training, or tuning. Meta's Co-tracker was developed to track the path at a given location. By locating the stent area in fluoroscopy, the Co-tracker could continue to track movement even after the lumen area was filled with contrast. He claimed that while these technologies are not yet sufficient to analyze all cardiovascular imaging, AI advancements are expected to change the clinical environment in the near future. Figure 3. Application of general AI for segmentation of fluoroscopy Hot Topics MedTech Innovation Friday, April 26, 2:00 PM ~ 3:08 PM Presentation Room 1, Level 1 Check The Session

June 04, 2024 831

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