Can OCT Identify ACS Patients Who Don't Need Stents?

12th Biennial Meeting of the International Andreas Gruentzig Society:  Rio de Janeiro - February 2-6, 2014

From Session 1: Coronary

Can OCT Identify ACS Patients Who Don't Need Stents?

Moderator:      Steve Bailey
Panelists:      Larry Dean, George Hanzel, Tarek Helmy, Bonnie Weiner, Peter Wijngaard

Framing the question at hand, what is the state of the current knowledge?

Patients who present with STEMI and ACS have many different etiologies of coronary occlusion. In clinical and autopsy series, 15%-30% of ACS patients have coronary thrombosis due to plaque erosion.

The improved resolution of optical coherence tomography (OCT) has provided better image resolution, allowing us to assess different pathologic states such as plaque and cap thickness, plaque erosion and rupture. Prior studies suggest different natural histories and outcomes for patients with plaque erosion, as there is little underlying stenosis and flow limitation. The patients also are more often women and active smokers.

What are the Gaps in the current knowledge?

OCT is a new, relatively expensive device that is not widely used currently. We do not have trials using OCT in the acute setting that have quantified the number of non-occlusive plaque rupture lesions. There is concern about using OCT with flush during a STEMI.

OCT has not been used in large series to guide therapy based upon lesion identification. Other considerations would be what approach would we take with other severe non-culprit lesions that may be identified.

Do patients treated medically change the lesion characteristics — ie, do they heal? Limited serial OCT studies do support the hypothesis that this approach would work, but it is unproven. We also do not know the best therapy for lesion subtypes, as it may vary.

Our Summary and Recommendations:
Well-constructed prospective detailed study is first needed to characterize the patients in this setting.  We have limited short-term data regarding outcomes in patients who are felt to have predominately thrombus with plaque erosion who are treated only with medical therapy. Currently, we continue to debate when an ACS patient becomes a stable patient using current OCT.  Is it at 48 hours, 7 days, or 30 days, or is it longer? We have no long-term data in these patients, and we need to append existing registries to help with this information.

As we currently have no clinical algorithm, studies will be needed to define lipid core index stability. Plaque erosion may need to include multiple modalities including angiographic evaluation  –►  FFR  –►  OCT –►  stent vs no stent –► late outcomes. Answering these questions would require a multicenter study, which would be expensive and require multiple industry partners and NIH/NHLBI support.