Can you tell us what your study found out about the impact of commissural versus coronary alignment for TAVR?

Gilbert Tang, MD: What we did in this study is actually quite interesting. The question is whether it would be better to do coronary alignment instead of commissural alignment to help access both coronaries. We wanted to determine how serious the problem of coronary overlap and misalignment actually is. Do you need to do coronary alignment in every single case or is it only in a fraction of the cases?

We looked at over 1000 patients, looking at the pre-op CT, to try to predict whether or not coronary alignment was necessary for the TAVR procedure to get an optimal result. We looked at the eccentricity of the coronary arteries and also the cusp asymmetry.

We found that the left main is mostly centered at the center of the left sinus other than in some locations where it is biased towards the non-left commissure. With the right coronary artery, however, the center is around 45 degrees, so it is actually a little closer to the non-right commissure, so it is a little more eccentric than the left main. The intercoronary angle is typically around 135 degrees rather than the theoretical 120 degrees.

Having said that, though, we found that for commissural alignment, the incidence of severe overlap with a coronary artery, meaning that a commissural post is facing one of the coronaries, is actually exceedingly low. For the left main, it is only around 1% to 2%. The odds for the right coronary are higher, around 3% (2.97%). Still, it is not like 20% or 30%, where that would be very alarming. The tradeoff, however, is that if you do coronary alignment, then you lose the benefit of having the commissure straddling the left main, because left main is really what you care most about. The left main is typically lower in height, harder to engage, and obviously is covering more territory. The rate of no overlap goes from 90+% with commissural alignment to around 85% with coronary alignment, which is statistically significant.

In addition, we found that it is only a small percentage of the time when you have an eccentric or anomalous coronary that coronary alignment is actually necessary to deal with that situation. With commissural alignment alone, the incidence of coronary overlap with the right coronary is exceedingly low and even lower with the left main. Only in about 5% of the cases would there be a benefit from coronary alignment because then you can access both coronaries without the potential physical barrier of one of the commissures.

You can identify those cases in advance with CT.

Gilbert Tang, MD: Correct, because you have the pre-procedural CT to see where the coronaries come off and so you can preplan your coronary alignment fluoroscopic angle. Rather than a cusp overlap view, you do a coronary overlap view to deploy the valve to target for the coronary alignment.

Find more: TVT Newsroom (With a Special Focus on TAVR)

Find Dr. Tang’s presentation slides here.

Read a previous CLD interview with Dr. Tang:
Transcatheter Aortic Valve Positioning: A Simple Technique to Ensure Future Coronary Access