Comparison of 6-month vascular healing response after bioresorbable polymer versus durable polymer drug-eluting stent implantation in patients with acute coronary syndromes: A randomized serial optical coherence tomography study

Objectives

This study was conducted to use optical coherence tomography (OCT) to compare vascular healing between bioresorbable polymer (BP) and durable polymer (DP) everolimus‐eluting stents (EES) in patients with acute coronary syndromes (ACS).

Background

Whether BP‐EES induce better vascular healing compared to contemporary DP‐EES remains controversial, especially for ACS.

Methods

In this prospective, randomized, non‐inferiority trial, we used OCT to compare 6‐month vascular healing in patients with ACS randomized to BP versus DP‐EES: percent strut coverage (primary endpoint, non‐inferiority margin of 2.0%) and neointimal thickness and percent neointimal hyperplasia (NIH) volume. As an exploratory analysis, morphological factors related to the endpoints and the effect of underlying lipidic plaque on stent healing were evaluated.

Results

A total of 104 patients with ACS were randomly assigned to BP‐EES (n = 52) versus DP‐EES (n = 52). Of these, 86 patients (40 BP‐EES and 46 DP‐EES) were included in the final OCT analyses. Six‐month percent strut coverage of BP‐EES (83.6 ± 11.4%) was not non‐inferior compared to those of DP‐EES (81.6 ± 13.9%), difference 2.0% (lower 95% confidence interval‐2.6%), p_{non‐inferiority} = 0.07. There were no differences in neointimal thickness 70.0 ± 33.9 μm versus 67.2 ± 33.9 μm, p = 0.71; and percent NIH volume 7.5 ± 4.7% versus 7.3 ± 5.3%, p = 0.85. By multivariable linear regression analysis, stent type was not associated with percent strut coverage or percent NIH volume; however, percent baseline embedded struts or stent expansion was positively associated with percent NIH volume. Greater NIH volume was observed in lipidic compared with non‐lipidic segments (8.7 ± 5.6% vs. 6.1 ± 5.2%, p = 0.005).

Conclusions

Six‐month strut coverage of BP‐EES was not non‐inferior compared to those of DP‐EES in ACS patients. Good stent apposition and expansion were independently associated with better vascular healing.

Serial evaluation of vascular responses after implantation of everolimus-eluting coronary stent by optical coherence tomography

AIM

To evaluate healing response at strut-level and cross-section level after implanting an ultra-thin strut, everolimus-eluting stent with biodegradable polymer (Tetrilimus) using optical coherence tomography (OCT) at 3 and 6 months.

METHODS

This was prospective, multi-centre, single-arm, and investigator-initiated study performed at seven Indian sites between January, 2017 and September, 2018. OCT evaluations were performed in 57 patients who underwent Tetrilimus stent implantation. Follow-up OCT was scheduled at 3 months for first 16 patients and at 6 months for 41 patients. Primary outcomes included degree of strut coverage, malapposition and thickness of neointimal hyperplasia (NIH) over covered struts.

RESULTS

Sixty one Tetrilimus stents were implanted to treat 59 lesions in 57 patients. Paired (baseline and follow-up) OCT data was available for 12 patients and 30 patients at 3 and 6 months, respectively. At 3 months, rapid early healing was indicated by 95.48% covered struts per lesion with very low (0.11 ± 0.06 mm) NIH. At 6 months, NIH accumulation was greater (0.21 ± 0.07 mm) as compared to 3 months. 99.77% of struts per lesion were covered at 6 months. There was a very symmetrical healing as shown by very low eccentricity index. There was no difference in vascular healing between stents with small to moderate size vessels (≤3.00 mm) and large size vessels (>3.00 mm).

CONCLUSION

Present study demonstrated nearly complete endothelization and low NIH accumulation at 3 and 6 months following implantation of ultra-thin strut everolimus-eluting biodegradable polymer-coated Tetrilimus stent. Moreover, though being an ultra-thin strut stent, there was no difference in vascular healing and eccentricity after implantation of the Tetrilimus stents with smaller and larger diameters.

Early vascular responses to everolimus-eluting cobalt-chromium stent in the culprit lesions of st-elevation myocardial infarction: results from a multicenter prospective optical coherence tomography study (MECHANISM-AMI 2-week follow-up study)

The use of cobalt-chromium everolimus-eluting stents (CoCr-EES) for ST-segment elevation myocardial infarction (STEMI) reduces the incidence of stent thrombosis compared with bare metal stents, and a substantial difference is apparent in the initial 2 weeks. However, vascular behavior during this early period remains unclear. This was a prospective study (MECHANISM-AMI-2W) to investigate early vascular responses in STEMI patients immediately after CoCr-EES implantation and at 2-week follow-up using frequency domain-optical coherence tomography (FD-OCT). The study enrolled 52 patients (age 63.7 ± 11.7 years, male 85.0%), of whom 44 patients were available for complete serial FD-OCT analyses. Both % uncovered struts and % malapposed struts were improved at 2-week follow-up (63 ± 20 vs. 21 ± 14%, p < 0.0001 and 7.3 ± 9.0 vs. 4.7 ± 5.9%, p = 0.005, respectively). Thrombus was decreased, with significant changes in longitudinal length to stent (28.8 ± 27.7 vs. 18.1 ± 20.2%, p = 0.0001) and maximal area (0.93 ± 0.84 vs. 0.65 ± 0.63 mm2, p = 0.034). As a result, the average lumen area was significantly larger at 2 weeks (6.49 ± 1.82 vs. 6.71 ± 1.89 mm2, p = 0.048, respectively). The number of dissection flaps was lower (0.86 ± 1.11 vs. 0.52 ± 0.90%, p = 0.024). In conclusion, this study showed early vascular responses to CoCr-EES for STEMI lesions-including a significant reduction of thrombus-that resulted in lumen enlargement, earlier progression of strut coverage, and improvements in strut apposition and dissection. The combination of these factors may therefore be responsible for the safety of CoCr-EES within the initial 2 weeks.

Initial and late efficacy of everolimus-eluting stents for small and non-small coronary lesions from evaluating delayed late loss study

The aim of the present study was to evaluate the long-term outcomes at 2 years in patients in whom everolimus-eluting stents (EESs) were implanted in small and non-small vessels. A small vessel is an important risk factor for restenosis with BMSs, even in the first generation DESs. The 690 patients with 690 lesions implanted with an EES were enrolled and divided into two groups by vessel reference diameter (RD): >2.5 mm for non-small vessels (Non-S-group) and ≤2.5 mm for small vessels (S-group). Two years later, the 365 patients with no restenosis at 8 months who underwent angiography were enrolled into the late catch-up study. At the initial 8-month follow-up, the rates of restenosis and target lesion revascularization (TLR) of both groups were not significantly different (restenosis 3.9 vs 6.5%, p = 0.17; TLR 3.9 vs 6.5%, p = 0.17). At the late 2-year follow-up, there were no significant differences in the late loss (0.36 ± 0.66 vs 0.34 ± 0.50 mm, p = 0.14), net gain (1.50 ± 0.75 vs 1.26 ± 0.60 mm, p = 0.39), late catch-up restenosis rate (5.1 vs 3.4%, p = 0.38), TLR (4.9 vs 2.7%, p = 0.40), and delayed late loss (0.14 ± 0.58 vs 0.15 ± 0.49 mm, p = 0.10) between both groups. There is no correlation between delayed late loss and RD in all patients(r = -0.009) and in AMI patients (r = -0.004). These results demonstrate that the initial and late catch-up restenosis rates of small coronary vessels with EES placement were excellent, the same as for non-small coronary vessels. We suggest that involvement of small coronary arteries may not be a risk factor for restenosis and results of stenting for small coronary arteries with EES placement were excellent.

Very early tissue coverage after drug-eluting stent implantation: an optical coherence tomography study

The aim of this study was to evaluate neointimal coverage in the very early phase after second-generation drug-eluting stent (DES) implantation using optical coherence tomography (OCT). Patients who underwent staged percutaneous coronary intervention within 30 days after DES implantation were enrolled. OCT was performed to observe DES previously implanted. The median time interval from implantation to OCT examination was 21.5 days. A total of 10,625 struts of 54 stents (52 everolimus-eluting stents and 2 zotarolimus-eluting stents) in 42 lesions were analyzed. Strut tissue coverage was observed in 71.1 ± 19.2 % of the struts, malapposed struts in 2.56 ± 3.37 %, strut tissue coverage at the side branch orifice in 10.6 ± 17.2 %, and struts with protrusion in 0.95 ± 3.46 %. Mean tissue thickness on the covered struts was 39.8 ± 14.2 µm. The percentage of stent coverage was significantly lower in the overlapping segments than in the non-overlapping segments (48.4 ± 17.5 % vs. 74.4 ± 20.2 %, P < 0.05). Most of the stent struts were covered by tissue within 30 days after second-generation DES implantation. However, the percentage of strut coverage was lower in the overlapping segments than in the non-overlapping segments, suggesting that very early interruption of dual antiplatelet therapy might result in increased risk of stent thrombosis, even in second-generation DES.

A 12-month angiographic and optical coherence tomography follow-up after bioresorbable vascular scaffold implantation in patients with ST-segment elevation myocardial infarction

OBJECTIVES

The aim of the study was to evaluate the healing process at 12 months after ABSORB™ bioresorbable vascular scaffold (BVS) implantation in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

There is currently no data on long-term BVS performance in the acute thrombotic setting. The underlying altered plaque pathomorphology may impact the neointima healing pattern, potentially making it different to that observed in stable coronary artery disease (CAD).

METHODS

We have performed an angiographic and optical coherence tomography (OCT) 12-month follow-up of 19 STEMI patients who were treated with a BVS implantation (23 scaffolds). An independent core laboratory performed a paired analysis of the corresponding frames at baseline and follow-up.

RESULTS

At 12 months, the OCT follow-up showed a decrease in the mean lumen area (8.29 ± 1.53 mm(2) vs. 6.82 ± 1.57 mm(2) , P < 0.001), but no significant change in the mean scaffold area (8.49 ± 1.53 mm(2) vs. 8.90 ± 1.51 mm(2) ). Significant decreases in malapposed strut ratio (4.9 ± 8.65% vs. 0.4 ± 1.55%, P < 0.001) and malapposition area (0.29 ± 0.60 mm(2) 0.08 ± 0.32 mm(2) , P = 0.002) were observed. A nonhomogenous proliferation of neointima was revealed with a symmetry index of 0.15 (0.08-0.27), a mean neointima thickness of 203 μm (183-249) and mean neointima area of 2.07 ± 0.51 mm(2) . The quantitative coronary angiography showed late lumen loss of 0.08 ± 0.23 mm and no significant change in the minimal lumen diameter (P = 0.11). There were no major adverse cardiovascular events (MACE), except for one nontarget vessel revascularization.

CONCLUSIONS

The OCT revealed a favorable healing pattern after BVS implantation in a STEMI population.

GPU-accelerated framework for intracoronary optical coherence tomography imaging at the push of a button

Frequency domain optical coherence tomography (FD-OCT) has become one of the important clinical tools for intracoronary imaging to diagnose and monitor coronary artery disease, which has been one of the leading causes of death. To help more accurate diagnosis and monitoring of the disease, many researchers have recently worked on visualization of various coronary microscopic features including stent struts by constructing three-dimensional (3D) volumetric rendering from series of cross-sectional intracoronary FD-OCT images. In this paper, we present the first, to our knowledge, "push-of-a-button" graphics processing unit (GPU)-accelerated framework for intracoronary OCT imaging. Our framework visualizes 3D microstructures of the vessel wall with stent struts from raw binary OCT data acquired by the system digitizer as one seamless process. The framework reports the state-of-the-art performance; from raw OCT data, it takes 4.7 seconds to provide 3D visualization of a 5-cm-long coronary artery (of size 1600 samples x 1024 A-lines x 260 frames) with stent struts and detection of malapposition automatically at the single push of a button.