Response by Mitomo et al to Letter Regarding Article, "Bioresorbable Vascular Scaffolds for the Treatment of Chronic Total Occlusions: An International Multicenter Registry"

Bioresorbable Scaffold Use in Coronary Chronic Total Occlusions: A Long-Term, Single-Center Follow-Up Study

Background and Objectives: Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is often associated with longer total stent length. Our aim was to evaluate the long-term safety and effectiveness of bioresorbable scaffold (BRS) implantation in CTO to avoid using a full metal jacket. Materials and Methods: We conducted a single-center prospective longitudinal case study including 34 patients who underwent PCI of CTO with at least one BRS and drug-eluting stent (DES) implantation (n = 27) or BRS-only at the Latvian Centre of Cardiology between 2016 and 2018. Quantitative coronary angiography (QCA) and intravascular ultrasound were performed during the index procedure and long-term follow-up. Results: Of 34 patients with a mean age of 60.6 ± 9.5 years, 76.5% were male. The most common CTO artery was the right coronary artery (73.5%, n = 25). The median length of occlusion was 23.0 mm (interquartile range (IQR) = 13.9-32.7), with a total mean BRS/DES length of 49.6 ± 20.4 mm. During the median follow-up of 5.6 years (IQR = 5.0-5.9), the primary endpoint of target vessel re-occlusion occurred in 5.9% (n = 2) of patients. Target lesion revascularization (TLR) was performed in 35.3% (n = 12) of patients, with a mean time to TLR of 62.5 (95% confidence interval (CI), 53.9-71.2) months. Through QCA, there was a statistically significant increase in median residual diameter stenosis (20.1-31.4%, p < 0.01) and residual length of stenosis (5.2-7.1%, p = 0.04) compared with the index procedure. Conclusions: Our study demonstrates that BRS is a safe and feasible option for PCI of CTO, allowing for the avoidance of long segment stenting and ensuring long-term patency of the coronary artery.

Impact of Selection Preference on Longer-Term Outcomes between Bioresorbable Vascular Scaffold versus Everolimus-Eluting Stent for True Lumen Tracking-Recanalized Chronic Total Occlusion

Creation of sizable subintima during intervention for chronic total occlusions (CTO) could lead to the key selection preference of metallic stents rather than bioresorbable vascular scaffolds (BVS) and then possibly deviate the outcome comparisons in real-world studies. By including recanalized CTO with true lumen tracking, we tested if any selection preference remained and compared the outcomes between everolimus-eluting stent (EES) and BVS implantation.Among 211 consecutive CTO interventions with true lumen tracking from August 2014 to April 2018 when BVS was available, we compared the clinical and interventional features between 28 patients with BVS and 77 patients with EES implantation. With propensity score matching and a median follow-up of 50.5 (37.3-60.3) months, we further assessed 25 patients with BVS and 25 with EES for target vessel failure (TVF: cardiac death, target vessel myocardial infarction, and target lesion revascularization).Multivariate analyses showed that BVS was still favored in the presence of LAD CTO (odds ratio (OR) = 3.4, 95% confidence interval (CI) = 1.0-11.7) and an average scaffold/stent size ≥ 3 mm (OR = 10.5, 95% CI = 3.0-37.3). EES was preferred for lesions with a J-CTO score ≥ 3 (OR = 19.3, 95% CI = 3.4-110.8) and multivessel intervention necessary at index procedure (OR = 11.3, 95% CI = 1.9-67.3). With matched comparisons, the TVF-free survival of EES was better than that of BVS for CTO recanalization (P = 0.049 by log-rank test) at long-term follow-up.Even with true lumen tracking techniques, selection bias remained substantial when determining either device for CTO implantation. The matched comparison of outcomes suggested the unfavorable longer-term impacts of the first generation of BVS on CTO lesions.

Bioresorbable vascular scaffolds for percutaneous treatment of chronic total coronary occlusions: a meta-analysis

BACKGROUND

BRS represent a new approach to treating coronary artery disease. Beneficial properties of BRS regarding the restoration of vasomotility after resorption make them attractive devices in CTO revascularization. However, experience in this setting is limited.

METHODS

We systematically searched Medline, Scholar, and Scopus for reports of at least 9 patients with CTO undergoing BRS implantation. Patients' and procedural characteristics were summarized. The primary outcome of interest was target lesion revascularization (TLR). Pooled estimates were calculated using a random-effects meta-analysis. The study protocol was registered in PROSPERO (CRD42017069322).

RESULTS

Thirteen reports for a total of 843 lesions with a median follow-up of 12 months (IQR 6-12) were included in the analysis. At short-term, the summary estimate rate of TLR was 2.6% (95% CI: 1 to 4%, I2 = 0%, P = 0.887) while at mid to long-term it was 3.8% (95% CI: 2 to 6%, I2 = 0%, P = 0.803). At long-term follow-up (≥12 months), the summary estimate rate of cardiac death was 1.1% (95% CI: 0 to 2%, I2 = 0%, P = 0.887). The summary estimate rates of scaffold thrombosis and clinical restenosis were respectively 0.9% (95% CI: 0 to 2%, I2 = 0%, P = 0.919) and 1.8% (95% CI: 0 to 4%, I2 = 0%, P = 0.448). Finally, the summary estimate rate of target vessel revascularization was 6.6% (95% CI: 0 to 11%, I2 = 0%, P = 0.04).

CONCLUSIONS

Implantation of BRS in a population with CTO is feasible, although further longer-term outcome studies are necessary.

Predictors of early scaffold thrombosis: results from the multicenter prospective German-Austrian ABSORB RegIstRy

BACKGROUND

In randomized clinical trials, the risk of thrombotic events with the absorb bioresorbable vascular scaffold (BVS) was significantly higher than with metallic drug-eluting stents. We evaluated predictors of scaffold thrombosis in the large-scale, multicenter German-Austrian ABSORB RegIstRy.

METHODS AND RESULTS

3178 patients with treatment of 4252 lesions using 5020 scaffolds were included. Follow-up rate at 6 months was 97.4%. Forty-five (1.42%) patients experienced definite/probable scaffold thrombosis during follow-up. Multiple regression analysis showed implantation of absorb BVS in bifurcation lesions [odds ratio (OR): 4.43; 95% confidence interval (CI): 1.69-11.59; P=0.0024] or treatment in the years 2013/2014 (OR: 1.88; 95% CI: 1.02-3.47; P=0.04) to be significant predictors of scaffold thrombosis. Excluding bifurcation lesions, the incidence of definite/probable scaffold thrombosis decreased from 1.8% (95% CI: 1.17-2.64%) in 2013/2014 to 0.89% (95% CI: 0.5-1.46%) in 2015/2016. In the latter period, absorb BVS were implanted more often in younger patients with less complex de novo lesions, and debulking devices and postdilatation were used more frequently. Between the two treatment periods, there was a significant reduction in myocardial infarction (2.73-1.24%, P<0.01; OR: 0.45; 95% CI: 0.26-0.77), definite/probable scaffold thrombosis (1.79-0.88%, P<0.05; OR: 0.49; 95% CI: 0.26-0.93), and target lesion failure and revascularization during follow-up.

CONCLUSION

Improved procedural technique and more strict patient selection may explain a significant decrease in the absorb BVS thrombosis rates during the recruitment period of the large-scale German-Austrian ABSORB RegIstRy. In addition, treatment of bifurcation lesions was identified as an independent predictor of definite/probable scaffold thrombosis.

Vascular response and healing profile of everolimus-eluting bioresorbable vascular scaffolds for percutaneous treatment of chronic total coronary occlusions: A one-year optical coherence tomography analysis from the GHOST-CTO registry

BACKGROUND

Bioresorbable vascular scaffolds (BVS) have been heralded with potential benefits that are especially desired in long lesions, including chronic total occlusions (CTOs). Procedural feasibility and mid-term outcomes of BVS in CTOs have been reported. However, there is still a paucity of data regarding the vascular and healing response to BVS in CTOs evaluated by optical coherence tomography (OCT).

METHODS

This study included prospectively 21 patients who had a CTO lesion treated with a BVS. Angiography and OCT scan were recorded at either post-implantation and 1-year follow-up. Quantitative coronary angiography and OCT analyses were performed by an independent core laboratory.

RESULTS

The angiographic analysis showed a significant increase in the percentage of in-segment diameter stenosis at 1year (11.89±9.5% vs. 21.84±11.7%; p=0.002). The OCT analysis showed a trend (p=0.07) towards increased mean scaffold area and significant reductions in mean lumen diameter (3.1±0.36mm vs. 2.85±0.47mm; p=0.0046), mean lumen area (7.8±1.73mm² vs. 6.76±2mm²; p=0.0082) and minimal lumen area (5.26±1.86mm² vs. 3.56±1.52mm²; p<0.0001). Malapposition area and volume decreased from 0.26±0.17mm² to 0.08±0.1mm² (p=0.0003) and from 14.17±12.92mm³ to 3.99±4.46mm³ (p=0.0014), respectively. The rate of uncovered or malapposed struts, measured at the frame level, was 5.29±6.48% at 1year.

CONCLUSIONS

In a small series of CTO patients treated with BVS implantation, OCT outcomes at 1year displayed an overall favorable vascular response and healing profile.