Risk there a risk of valve collapse from just an alarplasty?

I've never done an alarplasty which created breathing problems. If it's just narrowing the nostrils and nothing else you will be fine

There is no risk of nasal valve collapse from Alarplasty as it is not close to the valve area. However, if done aggressively it can narrow the nostril itself and hamper breathing.
Regards
Dr. J

Can an alar plasty cause valvular collapse? There are two sets of valves. The internal valves which are sometimes the subject of collapse after rhinoplasty are not affected by an Alarplasty. But the nostril openings constitute the external valves and if the alar plasty is done too aggressively and the nostrils made too thin this will compromise the flow of air through the external valves.