March 18, 2017
Dear Cardiovascular Specialists and Interventional Cardiologists,
The FDA is informing health care providers treating patients with Absorb GT1 Bioresorbable Vascular Scaffold (BVS) that there is an increased rate of major adverse cardiac events observed in patients receiving the BVS, when compared to patients treated with the approved metallic XIENCE drug-eluting stent.
The BVS is used to open heart blood vessels (coronary arteries) blocked by scar tissue (plaque) in order to increase blood flow to the heart muscle. The BVS is implanted during an angioplasty procedure. It gradually dissolves and is fully absorbed by the body over time. The FDA approved the BVS in July 2016, and it is manufactured by Abbott Vascular, Inc.
ANALYSIS OF THE PROBLEM
The FDA's initial review of two-year data from the BVS pivotal clinical study (the ABSORB III trial) shows an 11 percent rate of major adverse cardiac events (e.g., cardiac death, heart attack, or the need for an additional procedure to re-open the treated heart vessel) in patients treated with the BVS at two years, compared with 7.9 percent in patients treated with the already-approved Abbott Vascular's metallic XIENCE drug-eluting stent (p = 0.03). This study also shows a 1.9 percent rate of developing blood clots (thrombosis) within the BVS versus 0.8 percent within the XIENCE stent at 2 years. These observed higher adverse cardiac event rates in BVS patients were more likely when the device was placed in small heart vessels.
An additional preliminary analysis of ABSORB III data suggests improved clinical performance and a lower rate of complications associated with BVS implantation when health care providers follow the recommended implantation methods. The FDA-approved labeling for the BVS includes recommendations on selecting appropriately-sized heart arteries for BVS implantation and methods to properly implant the device against the vessel wall.
In approving the BVS in July 2016, the FDA evaluated one-year data from the ABSORB III randomized study of 2,008 U.S. patients, which compared the rate of major adverse cardiac events between the BVS and the already-approved metallic XIENCE drug-eluting stent. After one year, the clinical results in patients treated with the BVS were comparable to those treated with the XIENCE stent. As a condition of approval, the FDA required Abbott Vascular to follow patients in the ABSORB III study for five years.
The ABSORB III study results are consistent with the trends observed in the recently published 3-year results from the ABSORB II study and the recently presented 2-year results from the ABSORB Japan study, which were conducted outside of the U.S. Use of the recommended BVS implantation methods per the BVS physician labeling has been incorporated in the ongoing ABSORB IV randomized study of the BVS vs. the Xience stent.
Patients treated with coronary stents are required to take dual antiplatelet therapy (DAPT), which consists of aspirin and a P2Y12 platelet inhibitor medication (another type of blood thinner) to prevent device blood clots. ABSORB II patients were prescribed DAPT for a minimum of six months, and ABSORB III and ABSORB Japan patients were prescribed DAPT for a minimum of 12 months. Among BVS-treated patients who developed device blood clots after one year in the ABSORB II, ABSORB III, and ABSORB Japan studies, most had discontinued DAPT.
The FDA recommends that health care providers:
- Follow the instructions for target heart vessel selection (e.g., avoiding BVS use in small heart vessels) and optimal device implantation that are included in the BVS physician labeling.
- Advise patients experiencing any new cardiac symptoms such as irregular heartbeats, chest pain, or shortness of breath to seek clinical care. For more information about risks associated with the BVS, refer to the BVS physician labeling.
- Advise BVS patients to follow the recommendations for DAPT prescribed by their health care providers.
- Report any adverse events related to the BVS that come to your attention. If you suspect a problem with the BVS, we encourage you to file a voluntary report through MedWatch, the FDA Safety Information and Adverse Event Reporting Program. Health care personnel employed by facilities that are subject to the FDA's user facility reporting requirements should follow the reporting procedures established by their facilities.
The FDA is working with Abbott Vascular, Inc. to conduct additional analyses to better understand the cause(s) of the higher cardiac event and device thrombosis rates in patients treated with BVS compared to the XIENCE stent. The FDA will continue to monitor the performance of the BVS in ongoing clinical studies and in reports submitted to FDA through MedWatch. We will update this communication when additional information or analyses become available.
If you have questions about this communication, please contact CDRH's Division of Industry Communication and Education (DICE) at DICE@FDA.HHS.GOV, 800-638-2041, or 301-796-7100.
William Maisel, MD, MPH
Deputy Center Director for Science
Center for Devices and Radiological Health
U.S. Food and Drug Administration