Author + information
- Nicolas Foin, MSc, PhD∗ (, )
- Alessio Mattesini, MD,
- Philip Wong, MD and
- Carlo Di Mario, MD, PhD
- ↵∗National Heart Research Institute Singapore, 5 Hospital Drive, Singapore 169609
In a recent paper, Puricel et al. (1) presented an interesting analysis of the mechanisms and predictors of bioresorbable scaffold thrombosis in a large registry of >1300 patients. Their analysis pointed to scaffold underexpansion and a final minimal scaffold diameter of <2.4 mm as predicator of scaffold thrombosis, with the smallest postprocedural minimal lumen diameter of <2.1 mm strongly associated with a risk of event.
The overall results of the ABSORB (ABSORB Bioresorbable Scaffold vs. Xience Metallic Stent for Prevention of Restenosis in Patients at High Risk of Restenosis) trial series have been overall reassuring and showed no difference in target lesion failure and clinical outcomes at 1 year. However, patients treated with biodegradable scaffold had nevertheless a twice higher risk of definite or probable stent thrombosis at 1 year compared with those treated with regular drug-eluting stents (DES) (odds ratio: 1.99; p = 0.05) (2). Subgroup analysis in the largest randomized study conducted so far (ABSORB III) has shown that bioresorbable vascular scaffolds (ABSORB BVS [Abbott Vascular, Abbott Park, Illinois]) implanted in smaller vessel diameter (<2.63 mm) had a higher 1-year rate of device thrombosis compared with Xience (Abbott Vascular) (2.3% vs. 0.9%; relative risk ratio: 2.65). However, BVS implanted in vessels >2.63 mm had no difference in device thrombosis at 1 year compared with metallic DES (0.8% vs. 0.6%; relative risk ratio: 1.28) (3).
So why does vessel reference size matter so much for bioresorbable technologies? The ABSORB BVS 2.5 and 3.0 sizes are actually the same device, mounted on different delivery systems, with important implications on the stent to artery ratio, which increases from 27% in a 3.0-mm vessel to 33% in a 2.5-mm vessel. In case the BVS is implanted in a very small vessel or remains underexpanded, the stent-to-artery ratio can increase to >40% at 2.0 mm, a large difference compared with a thin strut metallic stent like Xience, which has a stent-to-artery ratio of 13% at 3.0 mm and 20% when deployed in a 2.0-mm vessel, respectively (Table 1). This emphasizes the importance of using BVS in the appropriate reference vessel size until dedicated BVS design for smallest vessel sizes become available.
Please note: Dr. Mattesini has received consulting fees from Abbott. Dr. Di Mario has received a research grant from Abbott. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation