Can vessels become too small for stenting rapidly?

[MarieL5]

53yr old female with a stent at a bifurcation of the RCA at 43, no mention of small vessels. I had some issues found to be ischemia treated w/meds. Relocated in 9/12. Immediately made contact with a cardiologist in the new town. In 2015 began having chest pain, was catheterized. It was found that some plaque had formed in the LAD and that we would be keeping an eye on it. 5/16 was told that bypass surgery to LAD was needed, because it could not be stented. All labs, EKG and test were normal at all times.

[Ger57]

Arteries can become clogged over a period of many years, in some cases it can happen more rapidly.

Still, from what you describe, I guess that the reason that bypass surgery is advised is not that the LAD is too small.
The LAD is a big vessel and stents are placed in the LAD, even in cases where the LAD is fully blocked and has to be pried open first.

More likely is that you suffer from diffuse LAD stenosis, where the LAD is narrowed over a larger distance. Many stents would be needed to fully open up the LAD.
For more than one reason, a long series of stents in one artery is not optimal and bypass surgery is often preferred in diffuse artery disease.