Summer 2016 carried exciting news for bioresorbable scaffold (BRS) technology. On July 5, the US Food and Drug Administration (FDA) approved the Absorb GT1 (Abbott Vascular) poly(L-lactide) (PLLA)-based BRS for marketing in the United States. Three weeks earlier on June 15, the CE Mark for marketing in Europe was granted for Magmaris (Biotronik), the first metallic bioresorbable Magnesium-based scaffold. These approvals represent important milestones in the development of coronary BRS technology following nearly two decades of research and development from bench to bed. By now, the sponsors of these devices have begun their commercial launch with emphasis on training and education and strict adherence to the instruction for use (IFU) as stated in their approval documents.

In November 2015, I wrote an editorial in this journal entitled “Why Bioresorbable Vascular Scaffold Should Be Approved for Marketing in the United States” . The main arguments for approval were based on extensive preclinical and bench testing and data driven from the pivotal trial of ABSORB III , which met the endpoints of noninferiority to the best-in-class second-generation drug-eluting stents (DES). In addition, by that time there were over 100,000 implantations of Absorb outside of the United States, and the data from the post-marketing studies were reassuring. Finally, patients and physicians desired a BRS that would substitute a permanent metallic implant in the coronary arteries. On March 15, the FDA advisory panel gave near-unanimous support for approval of the Absorb GT1 Bioresorbable Vascular Scaffold (BVS) System. Following the sponsor and FDA presentations, testimonials from patients and physicians, and the sponsor commitment to conduct a robust post-marketing study, the panel deliberated and voted on the safety (9 yes, 1 no), efficacy (10 yes, 0 no), and risk/benefit profile (9 yes, 1 abstain) .

Among the concerns regarding the approval was the numerically higher rate of scaffold thrombosis and myocardial infarction when compared to the DES XIENCE (Abbott Vascular). Because most of the scaffold thrombosis occurred in the small vessel cohort, the sponsor proposed adding a warning to the label against implanting a BVS in vessels with a reference vessel diameter of <2.5 mm and a precaution statement strongly recommending online quantitative coronary angiography or intravascular imaging for small vessels visually assessed as ≤2.75 mm. Indeed, this proposal was adopted in the IFU as a warning that states: “In small vessels (visually assessed reference vessel diameter ≤2.75 mm), online quantitative coronary angiography or intravascular imaging with intravascular ultrasound or optical coherence tomography is strongly recommended to accurately measure and confirm appropriate vessel sizing. If quantitative imaging determines a vessel size <2.5 mm, do not implant the Absorb GT1 BVS.” To mitigate the risk of scaffold thrombosis, the IFU warning section states that “judicious selection of patients is necessary, since the use of this device carries the associated risk of scaffold thrombosis, vascular complications, and/or bleeding events.” Other warnings in the IFU relate to adequate lesion preparation and sizing. In addition, it is strongly recommended “to achieve a residual stenosis between 20% and 40% after pre-dilatation to enable successful delivery and full expansion of the scaffold and to ensure that the scaffold is not post-dilated beyond the allowable expansion limits” to minimize damage to the scaffold. Clearly, these IFU warnings and precautions related to the device are evidence that the Absorb GT1 is a unique device and not just another metallic stent. Caution should be exercised in patient and lesion selection and in handling the device with the appropriate implantation technique .

The Magmaris approval in Europe was based on a small registry of patients who enrolled into the BIOSOLVE-II study and had 12 months angiographic and clinical follow-up . The Magmaris IFU also includes specific recommendations that are unique to the device properties, including adequate vessel preparation, avoidance of calcified and thrombotic lesions, restriction of vessel diameter to between 2.7 and 3.2 mm for a scaffold diameter of 3.0 mm and a vessel diameter between 3.2 and 3.7 mm for a scaffold diameter of 3.5 mm. Moreover, upsizing of the device should be limited to 0.6 mm beyond the nominal size of the implanted scaffold. Although balloon pre-dilatation should be required for all lesions, balloon post-dilatation with a noncompliant balloon inflated with a pressure greater than 16 atmospheres and with the same nominal size as the scaffold implantation balloon or up to 0.5 mm larger is always recommended. Planning of overlapping with the Magmaris is not recommended .

The Absorb BRS was launched commercially in Europe and globally over 5 years ago. Shortly after, operators expanded its usage for nearly all patient and lesion subsets, including patients presenting with ST-segment elevation myocardial infarction, bifurcations, chronic total occlusion, and in-stent restenosis lesions. However, the data to support the safety and efficacy for these indications were sparse. This unleashed off-label usage of the Absorb, resulting in higher event rates, including higher scaffold thrombosis, especially in patients with acute coronary syndrome. The learning curve phase using a PLLA-based scaffold with higher strut thickness when compared to DES was not monitored carefully and resulted in higher than anticipated events.

With the launch of the Absorb GT1 in the United States and the Magmaris in Europe, we should apply the knowledge learned from past experiences by implementing the lessons from the initial launch of the Absorb globally and focus on adequate vessel preparation, assurance of scaffold expansion, avoidance of scaffold deformation, increase in the use of imaging-assisted scaffold deployment, and proper patient selection. Adhering to the IFU as we launch Absorb GT1 in the United States and Magmaris in Europe is imperative to avoid the mistakes of the past and to assure safety and effectiveness of the devices in our patients. Although, we are all eager to continue to expand the indications, we should move forward according to investigational protocols with rigorous monitoring and full transparency under guidance from the sponsors.

At this phase of the technology development and the clinical trials, we should remember that both Absorb GT1 and Magmaris did not demonstrate superiority over best-in-class DES. For Absorb, the data related to superiority will not be available for at least the next 7 years. In the case of Magmaris, the clinical data are sparse, and we should wait for the results of large post-marketing registries to understand the performance of the device and its role in clinical use. In addition, well-powered randomized studies are essential to position the performance of Magmaris versus best-in-class DES. These studies have not initiated yet. For both scaffolds, it is important to obtain long-term follow-up to demonstrate superiority of the BRS technology over best-in-class DES. Without that, promoting routine use of BRS technology would be difficult.

Currently, the usage of BRS globally is under 5%. There are many reasons for this low penetration rate, including the fear of scaffold thrombosis, lack of short-term benefit, incomplete matrix of sizes and lengths, and a suboptimal profile of the device when compared to DES. With the approval for marketing of Absorb GT1 in the United States and Magmaris in Europe, BRS technology has a second chance to launch in a proper and controlled way for the right patient population and lesion subset, adhering to the optimal technique requirement, which hopefully will deliver the best clinical outcome for our patients.

We should recognize that both Absorb GT1 and Magmaris are first-generation devices. The approval for marketing was based on a scientific promissory hypothesis that over time these devices will minimize the stent-related events; however, to date that has not been proven. Therefore, at this stage of the development of the current technology and with the followers who are working diligently on improving the mechanical properties of the BRS devices, we must handle with care the approved devices and let this promising and exciting field thrive.