Mechanisms of Very Late Bioresorbable Scaffold Thrombosis Assessed by Optical Coherence Tomography: Insights From the International INVEST Registry

Background: The 3-year clinical outcome data of ABSORB II study failed to reach the two co-primary endpoints of vasomotion and late loss, but also reported a higher risk of definite or probable stent thrombosis throughout 3 years (3% vs 0%, p=0.03) with the Absorb BVS compared with the metallic EES as well as myocardial infarction.(1) In addition, a numerically higher rate of definite very late device thrombosis (2% vs 0%, p=0.19) was observed. In ABSORB Japan study, malapposition and late strut discontinuities were observed at the timepoint of very late scaffold thrombosis in all the 4 cases of definite very late scaffold thrombosis.(2,3) There is mounting evidence from other studies with extended follow-up supporting the notion of an increased risk of very late scaffold thrombosis. While the causes of acute scaffold thrombosis are explained at least in part (i.e. underexpansion, increased strut thickness), the causes underlying thrombotic events occurring beyond one year after scaffold implantation remain unclear and require investigation in an independent manner.

The investigators have previously reported that scaffold discontinuity and restenosis during the resorption process may provide mechanistic explanations for very late scaffold thrombosis.(4) As this report was based on a limited number of cases, the investigators extend the OCT database to comprehensively study the phenomenon very late scaffold thrombosis.

Rationale: The investigators consider the establishment of an independent OCT registry of paramount important as more than 150 000 patients have been implanted with Absorb BVS worldwide. The findings may provide important insights to identify patients at increased risk in addition to considerations regarding long-term antiplatelet therapy.

Objectives: The specific aim is to systematically analyse scaffold thrombosis occurring beyond 1 year after implantation of a Absorb BVS 1.1 investigated by OCT at the timepoint of thrombosis (either prior or after thrombus aspiration).

Primary and secondary endpoint/outcome(s): The primary endpoint is the underlying main reason for stent thrombosis as per quantitative and qualitative analysis and per expert panel consensus. To investigate the underlying mechanisms of very late scaffold thrombosis, the investigators will systematically assess the following parameters: