JACC: Bioresorbable Vascular Scaffolds vs. Metallic Stents in Patients with CAD: ABSORB China Trial

Educational Objectives

Discuss current research findings on the use of bioresorbable vascular scaffolds versus metallic stents in patients with coronary artery disease.

Summary

Take-home Messages:

• Bioresorbable vascular scaffolds (BVS) have emerged as a promising new link in the long chain of major breakthroughs in intracoronary device technology.
• BVS provide temporary vessel support, retain the ability of antirestenotic drug elution, and dissolve within a well-defined time frame.
• In the multicenter, randomized ABSORB China trial, a polylactide-based BVS was noninferior to the cobalt chromium everolimus-eluting (CoCr-EES) Xience stent platform for the primary endpoint of in-segment late loss at 1 year.

Compared with bare-metal stents (BMS), drug-eluting stents (DES) decrease the risk of restenosis without increasing the risk of death and myocardial infarction. However, unlike their bare-metal counterparts, DES are associated with hypersensitivity reactions, delayed healing, and incomplete endothelialization, which may increase the risk of late and very late stent thrombosis.

In acute coronary syndrome, current guidelines recommend at least 12 months of dual antiplatelet therapy (DAPT) after placement of a DES as a prophylactic measure to prevent thrombosis. However, updated guidelines recently changed the recommendation for patients with stable ischemic heart disease undergoing implantation of safer, newer-generation DES: the minimum recommended duration of DAPT has been decreased from 12 to 6 months.¹ It’s important, given that prolonged use of DAPT increases bleeding risk, requires good patient compliance, and adds to cost.

The advent of bioresorbable stents was considered one possible answer to the dilemma of getting the benefits of stenting with less long-term risk. Efforts to develop the devices began about 20 years ago, and the world first learned of their clinical use in 2000.² The “disappearing” stent became commercially available 11 years later, when the Absorb bioresorbable vascular scaffold (BVS) from Abbott Vascular (Santa Clara, California) became the first of its kind to be approved for use in Europe. The everolimus-eluting device won its approval based on results of the ABSORB clinical trials, which showed the stent restored blood flow by opening a blocked vessel and provided support to that vessel until it dissolved after about 2 years.³

In the summer of 2016, the Absorb GT1 BVS was approved by the Food and Drug Administration. The stent is made of a biodegradable polymer called poly(L-lactide), which is similar to materials used in other types of absorbable medical devices. Once the product disintegrates, within about 3 years, 4 platinum markers are left to indicate where the stent had been implanted.

BVS devices provide temporary vessel support, retain the ability of antirestenotic drug elution, and dissolve within a well-defined time frame. Due to this principal function, BVS may provide therapeutic features that could extend well beyond current metallic DES by enabling positive vessel remodeling and late lumen gain, enhancing the process of long-term arterial healing, entailing plaque shielding properties, and restoring physiologic vasomotion.

ABSORB China

Recently, investigators reported 1-year angiographic and clinical results of the ABSORB China trial (A Clinical Evaluation of Absorb Bioresorbable Vascular Scaffold System in a Chinese Population), designed to enable regulatory approval of the BVS in China. A total of 480 patients were randomized with up to 2 de novo lesions in a 1:1 fashion to Absorb BVS or the metallic Xience CoCr-EES platform.⁴ Acute clinical device success and procedural success were comparable (Table). The primary endpoint of in-segment late loss at 1 year also was similar; the 1-sided 97.5% upper confidence limit of the difference was 0.14 mm, achieving noninferiority of BVS compared with CoCr-EES (p for noninferiority = 0.01).

Minimal lumen diameter was smaller (Table) and percent diameter stenosis was greater for the BVS, whereas in-segment measures did not differ.

BVS and CoCr-EES also had similar 1-year rates of target lesion failure (p = 0.62) and definite/probable scaffold/stent thrombosis (p = 1.00).

What will the penetration of bioresorbable stents be in routine interventional practice within the next several years? In an accompanying editorial comment, Stephan Windecker, MD, et al. noted that the answer will be determined largely by their impact on patient outcomes.⁵ It is increasingly challenging, they wrote, for new intracoronary devices to achieve meaningful improvements against the current standard of care. Complex populations and longer follow-up durations will be critical to definitively establish at least the noninferiority of the BVS (or similar scaffolds under development) versus the best available metallic DES.

Summarizing the facts and fiction of the Absorb BVS, Windecker and colleagues noted that the theoretical advantages of “uncaging” the treated vessel are substantial, yet the BVS (and other emerging device technologies) somehow pay the price of current standards being extraordinarily high with new-generation DES.

They added that the results need to be further corroborated and carefully weighed against concerns regarding thrombotic complications in larger, broadly inclusive, longer-term studies, also addressing issues of cost effectiveness and optimal adjunctive antiplatelet regimens

Selected Outcomes from ABSORB China

	BVS (n = 241)	CoCr-EES (n = 239)	p Value
Acute success	98.0%	99.6%	0.22
Procedural success	97.0%	98.3%	0.37
	2.27 ± 0.03 mm	2.50 ± 0.03 mm	<0.001
diameter stenosis	18.5 ± 0.92%	11.3 ± 0.76%	<0.001
Late loss at 1 year*	0.19 ± 0.38 mm	0.13 ± 0.38 mm	0.01†
Target lesion failure	3.4%	4.2%	0.62
Definite/probable scaffold/stent thrombosis	0.4%	0.0%	1.00

*Primary endpoint

†Noninferiority

BVS = bioresorbable vascular scaffold; CoCr-EES = cobalt-chromium everolimus-eluting stent.

Readings

1. Levine GN, Bates ER, Bittl JA, et al. 2016 ACC/AHA guideline focused update on duration of dual antiplatelet therapy in patients with coronary artery disease: an update of the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention, 2011 ACCF/AHA guideline for coronary artery bypass graft surgery, 2012 ACC/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease, 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction, 2014 ACC/AHA guideline for the management of patients with non–ST-elevation acute coronary syndromes, and 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery. J Am Coll Cardiol 2016;68: [Epub ahead of print]. http://content.onlinejacc.org/article.aspx?doi=10.1016/j.jacc.2016.03.513

2. Tamai H, Igaki K, Kyo E, et al. Initial and 6-month results of biodegradable poly-l-lactic acid coronary stents in humans. Circulation 2000;102:399-404.

3. Serruys PW, Ormiston JA, Onuma Y, et al. A bioabsorbable everolimus-eluting coronary stent system (ABSORB): 2-year outcomes and results from multiple imaging methods Lancet 2009;373:897-910.

4. Gao R, Yang Y, Han Y, et al. Bioresorbable Vascular Scaffolds Versus Metallic Stents in Patients with Coronary Artery Disease: ABSORB China Trial. J Am Coll Cardiol 2015;66:2298-309. http://content.onlinejacc.org/article.aspx?articleID=2457324

5. Windecker S, Koskinas KC, Siontis GM. Bioresorbable Scaffolds Versus Metallic Drug-Eluting Stents: Are We Getting Any Closer to a Paradigm Shift? J Am Coll Cardiol 2015;66:2310-4. http://content.onlinejacc.org/article.aspx?articleID=2461772

Disclosures

Valentin Fuster, MD, PhD, MACC
This author has nothing to disclose.

The planning committee reported nothing to disclose.

A = Advisory panel B = Speakers’ bureau C = Consultant fees/honoraria D = Data and Safety Monitoring Board E = Equity interests/stock options F = Fellowship support G = Grant support L = Licensing Agreement O = Other relationship R = Royalties S = Salary W = Expert witness

Acknowledgements

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