ABSORB IV Results Show Need for Improvements in BVS Technology and Technique
October 31, 2017—Thirty-day results from ABSORB IV randomized everolimus-eluting trial of the Absorb bioresorbable vascular scaffold (BVS; Abbott Vascular) found the BVS to be noninferior to a cobalt-chromium everolimus-eluting stent (CoCr-EES) for target lesion failure (TLF). The findings were reported at TCT 2017, the 29th annual Transcatheter Cardiovascular Therapeutics scientific symposium being held October 30 to November 2 in Denver, Colorado. The ABSORB IV trial was funded by Abbott Vascular.
As background, first-generation BVSs have been associated with higher rates of TLF and device thrombosis as compared with current metallic drug-eluting stents. It has been thought that this may be in part due to a suboptimal implantation technique used in early studies. Therefore, the ABSORB IV trial mandated the avoidance of smaller vessels and emphasized aggressive predilatation and routine high-pressure postdilatation.
Additionally, ABSORB IV permitted the enrollment of more complex and higher-risk patients than ABSORB III, with the inclusion of troponin-positive acute coronary syndrome and up to three lesions in a maximum of two epicardial coronary arteries, including thrombus. Patients were randomized 1:1 to BVS or CoCr-EES after successful predilatation with a 1:1 sized balloon.
As summarized in the TCT announcement, ABSORB IV included 2,604 patients from 140 sites in five countries treated between August 15, 2014 and March 31, 2017. The patients were randomized 1:1 to BVS (n = 1,296) or CoCr-EES (n = 1,308). The median age was 63 years, 28% of patients were female, and 31.7% had diabetes. Among patients receiving BVS, predilatation was performed in 99.8% of lesions and postdilatation was performed in 82.6% of lesions. Acute device success (delivery and deployment of the study scaffold/stent with residual stenosis < 30%) was 94.6% for BVS compared to 99% for CoCr-EES (P < .0001).
The primary endpoint of 30-day TLF was 5% for BVS versus 3.7% for CoCr-EES (difference, 1.29%; Pnoninferiority = .02; Psuperiority = .11). As-treated 30-day TLF was 4.6% for BVS versus 3.7% for CoCr-EES (difference, 0.83%; Pnoninferiority = .006).
Patient-oriented major adverse cardiac events were 5.2% for BVS compared to 4.1% for CoCr-EES (P = .17). However, the rate of 30-day ischemia-driven target vessel revascularization was 1.2% versus 0.2% (P = .003), and the rate of device thrombosis was 0.6% in the BVS group and 0.2% in the CoCr-EES group (P = .06).
ABSORB IV Study Chair Gregg W. Stone, MD, commented in the TCT announcement, “At 30 days, BVS was noninferior to CoCr-EES for target lesion failure. The rates of nonperiprocedural myocardial infarction and ischemia-driven target vessel revascularization at 30 days were greater with BVS than with CoCr-EES, and a trend toward greater stent thrombosis with BVS was present. Compared to ABSORB III, reducing the number of very small vessels treated in ABSORB IV substantially reduced the device thrombosis rate in both groups. These results are largely consistent with those from earlier ABSORB trials and highlight the need for continued advancements in device technology and standardized technique to further improve the early safety profile of BVS.” Dr. Stone is Professor of Medicine at Columbia University Medical Center and Director of Cardiovascular Research and Education at the Center for Interventional Vascular Therapy at NewYork-Presbyterian Hospital in New York, New York.