Your way of thinking is not really correct. The coronary arteries are blood vessels which feed the heart to keep it alive and give it energy. The coronary arteries are not the vessels which actually feed the heart with blood to be pumped through the valves and through the body. Your heart would not receive any more blood into the chambers with the artery being opened up. Your heart may simply be working more efficiently and pumping more blood with each cycle. More likely the valves had problems before but wasn't discovered or the condition was very mild then. Are the valves leaking mild/moderate or severe? I think you need a TEE scan to get a more detailed analysis.
I had bypass surgery for 95% clogged coronary artery. Couldn't do stents because of some slow bleeding from a hiatal hernia.
I'm wondering what procedure you had? Which coronary artery was unclogged through open heart surgery? Was it a bypass? The only unclogging I know of through open heart surgery is an endarterectomy, but this is very rarely used unless a bypass is being performed because of the very high risks.