Accuracy of coronary computed tomography angiography for bioresorbable scaffold luminal investigation: a comparison with optical coherence tomography

Discordance between Invasive and Non-Invasive Coronary Angiography: An In-Depth Functional and Anatomical Analysis

A 79-year-old male with chronic coronary syndrome with complex coronary artery disease was included in the first-in-man trial of surgical revascularization guided solely by coronary computed tomography angiography (CCTA) and fractional flow reserve derived from CCTA (FFRCT). In CCTA analysis, the patient had calcified three-vessel disease, with a global anatomical SYNTAX score of 27. In contrast, in the initial FFRCT, only the ramus intermediate stenosis was physiologically significant, with no other vessels having an FFRCT ≤ 0.80 (functional SYNTAX score of 2). Discordance between the results of the CCTA and FFRCT necessitated an in-depth analysis by using both invasive and non-invasive coronary angiography. Angiography-derived fractional flow reserve (FFR) confirmed that the stenosis in the proximal left anterior descending artery (LAD) was physiologically significant, while it remained functionally negative in the second assessment of FFRCT. Extensive calcification is the most plausible explanation for the underestimation of the stenosis of proximal LAD in CCTA-derived FFR technology.

Coronary Computed Tomography Angiography for the Assessment of Sirolimus-Eluting Resorbable Magnesium Scaffold

Background: Little evidence to date has described the feasibility and diagnostic accuracy of coronary computed tomography angiography (CCTA) with noninvasive fractional flow reserve (CT-FFR) in coronary vessels with resorbable magnesium scaffold (RMS). Methods: The SHERPA-MAGIC is a prospective study enrolling patients receiving RMS. The present analysis considered patients undergoing CCTA 18 months after the index procedure. CCTA images were employed to investigate reabsorption status, luminal measurements, and noninvasive FFR. Three-year follow-up was available for all patients. Results: Overall, 26 patients with a total of 29 coronary arteries treated with 35 RMS were considered. The most frequently involved vessel was left anterior descendent (LAD). Median stent length was 25 (20–25) mm, with a median diameter of 3 (3–3.5) mm. At 18-month CCTA, all scaffolded segments were patent. Complete RMS reabsorption was observed in 27 (93%, 95% CI 77–99%) cases. Median minimal lumen diameter (MLD) and area (MLA) of the scaffolded segments were 2.5 [2.1–2.8] mm and 6.4 [4.4–8.4] mm², respectively. Median CT-FFR was 0.88 [0.81–0.91]. Only one (3.5%) vessel showed a flow-limiting CT-FFR value ≤0.80. During the 3-year follow-up, only one (4%) adverse event was observed. Conclusions: In patients undergoing RMS implantation, CCTA including noninvasive CT-FFR evaluation is feasible and allows investigation of long-term RMS performance.

Virtual medicine: Utilization of the advanced cardiac imaging patient avatar for procedural planning and facilitation

Advances in imaging technology have led to a paradigm shift from planning of cardiovascular procedures and surgeries requiring the actual patient in a "brick and mortar" hospital to utilization of the digitalized patient in the virtual hospital. Cardiovascular computed tomographic angiography (CCTA) and cardiovascular magnetic resonance (CMR) digitalized 3-D patient representation of individual patient anatomy and physiology serves as an avatar allowing for virtual delineation of the most optimal approaches to cardiovascular procedures and surgeries prior to actual hospitalization. Pre-hospitalization reconstruction and analysis of anatomy and pathophysiology previously only accessible during the actual procedure could potentially limit the intrinsic risks related to time in the operating room, cardiac procedural laboratory and overall hospital environment. Although applications are specific to areas of cardiovascular specialty focus, there are unifying themes related to the utilization of technologies. The virtual patient avatar computer can also be used for procedural planning, computational modeling of anatomy, simulation of predicted therapeutic result, printing of 3-D models, and augmentation of real time procedural performance. Examples of the above techniques are at various stages of development for application to the spectrum of cardiovascular disease processes, including percutaneous, surgical and hybrid minimally invasive interventions. A multidisciplinary approach within medicine and engineering is necessary for creation of robust algorithms for maximal utilization of the virtual patient avatar in the digital medical center. Utilization of the virtual advanced cardiac imaging patient avatar will play an important role in the virtual health care system. Although there has been a rapid proliferation of early data, advanced imaging applications require further assessment and validation of accuracy, reproducibility, standardization, safety, efficacy, quality, cost effectiveness, and overall value to medical care.

Diagnostic Accuracy of Coronary CT Angiography for the Evaluation of Bioresorbable Vascular Scaffolds

OBJECTIVES

The purpose of this study was to assess the diagnostic accuracy of coronary computed tomography angiography (CTA) for bioresorbable vascular scaffold (BVS) evaluation.

BACKGROUND

Coronary CTA has emerged as a noninvasive method to evaluate patients with suspected or established coronary artery disease. The diagnostic accuracy of coronary CTA to evaluate angiographic outcomes after BVS implantation has not been well established.

METHODS

In the ABSORB II (A Bioresorbable Everolimus-Eluting Scaffold Versus a Metallic Everolimus-Eluting Stent II) study, patients were randomized either to receive treatment with the BVS or everolimus-eluting metallic stent. At the 3-year follow-up, 238 patients (258 lesions) treated with BVS underwent coronary angiography with intravascular ultrasound (IVUS) evaluation and coronary CTA. The diagnostic accuracy of coronary CTA was assessed by the area under the receiver-operating characteristic curve with coronary angiography and IVUS as references.

RESULTS

The mean difference in coronary CTA-derived minimal luminal diameter was -0.14 mm (limits of agreement -0.88 to 0.60) with quantitative coronary angiography as reference, whereas the mean difference in minimal lumen area was 0.73 mm² (limits of agreement -1.85 to 3.30) with IVUS as reference. The per-scaffold diagnostic accuracy of coronary CTA for detecting stenosis based on coronary angiography diameter stenosis of ≥50% revealed an area under the receiver-operating characteristic curve of 0.88 (95% confidence interval [CI]: 0.82 to 0.92) with a sensitivity of 80% (95% CI: 28% to 99%) and a specificity of 100% (95% CI: 98% to 100%), whereas diagnostic accuracy based on IVUS minimal lumen area ≤2.5 mm² showed an area under the receiver-operating characteristic curve of 0.83 (95% CI: 0.77 to 0.88) with a sensitivity of 71% (95% CI: 44% to 90%) and a specificity of 82% (95% CI: 75% to 87%). The diagnostic accuracy of coronary CTA was similar to coronary angiography in its ability to identify patients with a significant lesion based on the IVUS criteria (p = 0.75).

CONCLUSIONS

Coronary CTA has good diagnostic accuracy to detect in-scaffold luminal obstruction and to assess luminal dimensions after BVS implantation. Coronary angiography and coronary CTA yielded similar diagnostic accuracy to identify the presence and severity of obstructive disease. Coronary CTA might become the method of choice for the evaluation of patients treated with BVS.

Bioresorbable Scaffold: The Emerging Reality and Future Directions

In the era of drug-eluting stents, large-scale randomized trials and all-comer registries have shown excellent clinical results. However, even the latest-generation drug-eluting stent has not managed to address all the limitations of permanent metallic coronary stents, such as the risks of target lesion revascularization, neoatherosclerosis, preclusion of late lumen enlargement, and the lack of reactive vasomotion. Furthermore, the risk of very late stent, although substantially reduced with newer-generation drug-eluting stent, still remains. These problems were anticipated to be solved with the advent of fully biodegradable devices. Fully bioresorbable coronary scaffolds have been designed to function transiently to prevent acute recoil, but have retained the capability to inhibit neointimal proliferation by eluting immunosuppressive drugs. Nevertheless, long-term follow-up data of the leading bioresorbable scaffold (Absorb) are becoming available and have raised a concern about the relatively higher incidence of scaffold thrombosis. To reduce the rate of clinical events, improvements in the device, as well as implantation procedure, are being evaluated. This review will focus on the current CE-mark approved bioresorbable scaffolds, their basic characteristics, and clinical results. In addition, we summarize the current limitations of bioresorbable scaffold and their possible solutions.