Everyone has heard about the FDA advisory hearing for the Absorb scaffold by Abbott Vascular, but to recap, one of the issues that came up in connection with the trial data for the Absorb was the association between coronary artery vessel size and adverse events such as thrombosis. There was some question of whether intravascular ultrasound (IVUS) would be useful in cutting down on such events, maybe not a bad idea in principal given that the Absorb's struts are much thicker than those found in conventional device struts.

But that was just the beginning of the IVUS conversation. Several days later, I got involved in a Twitter conversation about all this with a couple of writers who know the cardiology space a lot better than I do, and I thought it might be interesting to bring this conversation to light here at MDD Perspectives.

No FDA mandate One of the members of the advisory panel for the Absorb had remarked that IVUS or OCT (I'm not sure which offhand, but I think he had said IVUS) is not routinely used for placement of coronary artery stents, but there was some disagreement in the Twitter discussion as to whether the evidence behind such uses of IVUS is particularly robust.

It struck me that there was some question in this Twitter discussion of whether FDA can mandate IVUS during placement of the Absorb, but that seems like a practice-of-medicine debate. If that's the case, I don't think the agency can pull that off quite yet.

Beyond that, I'm not sure payers would cover such imaging procedures in the absence of some compelling data. One item in the literature in support of IVUS showed up last year in JAMA, but payers are going to want more than one study about stents going into vessels with lesions at least 28 millimeters long. Plus the study was conducted in Korea.

I'm not saying this is all the data that are available for this conversation, but if this is all there is, I'd point out that FDA probably wouldn't take it at face value because it's an OUS study. And I see no reason payers would react differently. It'll be interesting to see whether this issue gets any bandwidth at the April 1-4 American College of Cardiology gabfest, too.

What are Abbott's imperatives On the other hand, one might think Abbott will try to discourage docs from dropping this device in patients whose vessels are in that danger zone for thrombosis. Assuming that's the case, this would seem to take some of the wind out of the IVUS discussion (it also strikes the casual observer that the last thing this company's investors want is another "DES trauma," as some at FDA described the late-stent thrombosis episode).

There are among a number of scribes who know cardiology a lot better than I do, so I can't take sides in the utility-of-IVUS debate without having to answer uncomfortable questions about why I think A and not B. All the same, I'm thinking that for at least the next year or two, the Absorb will go into those wider vessels without the benefits of IVUS, whatever they may be.