Loooks like your first mmode has a bit of SAM see the anterior mv leaflet flattening but your second one looks ok. From the video there is LV hypertrophy and some remodeling and fixed lvot impingement. If this is a big maine coon this LA may be normal for him or a mildly big… Tx or no Tx on these are all over the map… some may use ACEi which traitionally was considered contraindicated with SAM but that has largely gone away in many circles so acei could be considered. SAM I dont treat unnless RHR is > 200 as sam worsens with higher HR. In fact if this cat gets excited on the table you will often see SAM more readily. Atenolol if execise intollerance. But some would jst sit and wait and recheck in 6 mo. Not always easy to ensure a cat gets meds every day so I try to use what i think would really help. Some would atenolol acei and plavix this cat… others sit and wait. I may use an acei and recheck echo in 1-3 mo to assess the LA primarily and if tachycardic or ex intollerance I would add atenolol. But thats me.

Started Plavix .

Thank you EL 

We are planning a california trip in July, so this might work well