A randomized controlled trial led by Dr. Seung-Yul Lee published in Circulation: Cardiovascular Intervention showed that in patients who required percutaneous coronary intervention, the use of optical coherence tomography (OCT) to help guide bioresorbable vascular scaffold (BVS) implantation did not reduce the incidence of nonoptimal deployment as compared to angiography guided BVS implantation.
The previously published ABSORB II trial demonstrated that when compared to percutaneous coronary intervention (PCI) using a metallic everolimus-eluting stent, the use of an everolimus-eluting bioresorbable vascular stent led to inferior outcomes at 3 years. However, this may have been attributed to incomplete lesion coverage, under-expansion of the stent, and malposition. The trial highlighted the potential for using intravascular imaging to optimize BVS implantation. However, whether this would change outcomes is not known. OCT allows for accurate measurement of lumen dimensions and evaluation of scaffold performance as compared to other imaging techniques. The investigators wanted to determine whether OCT guidance would reduce the incidence of nonoptimal BVS deployment as compared to angiography alone.
The randomized controlled trial allocated patients in a 1:1 ratio to either angiography guided BVS implantation or OCT guided BVS implantation. Patients who were scheduled to undergo coronary angiography were eligible. Patients with significant coronary artery stenosis (more than 50%) who were planned to receive a single BVS of less than 28mm in length were included. The exclusion criteria included emergent PCI, unprotected left main disease and complex lesions. If the patient had more than 1 lesion that required treatment, all the lesions were treated with either angiography or OCT based on the arm that the patient was enrolled to. The primary outcome was OCT-defined nonoptimal deployment. This was measured at the end of the procedure and was defined as a minimal scaffold area of less than 5mm2, residual area stenosis of 20% or greater, major edge dissection or scaffold disruption.
A total of 176 patients were included in the trial (88 patients with 90 lesions in the OCT guided BVS group and 88 patients with 89 lesions in the standard angiography group). The recruitment process ended early because the manufacturer stopped making the BVS due to safety concerns. BVS deployment was nonoptimal in 35.2% of patients in the OCT group and 38.6% in the angiography guided group (difference of -3.7%, 95%CI -19% to 11.6%, p = 0.64). There were no procedural complications in either group. When the investigators explored the data further, they found that proper BVS sizing and post-dilation to a higher pressure was associated with a reduced rate of non-optimal BVS placement.
The current trial demonstrated that using OCT to help guide BVS placement did not reduce the incidence of non-optimal deployment. Although the study was prematurely terminated, the investigators noted that they did not expect to find a difference in the incidence of non-optimal deployment between the two groups. The investigators estimated that the primary outcome would occur in 60% of patients in the angiography group. As the study progressed, they found that the incidence was 38.6%, much lower than their initial assumption. However, the study does have its limitations. Due to the premature stopping of the trial, the investigators were only able to enroll 64% of planned enrollment. Additionally, the study did not investigate the relationship between nonoptimal OCT and the relevant clinical outcomes. Finally, the findings may not apply to patients with complex lesions. The potential benefit of OCT-guided BVS implantation may eventually become a topic for future trials.