Sorry to read about your fall, my sympathy and hope you are fully recovered. With AFib I assume you are also on a blood thinner, making any cut bleed more problematic.
Metoprolol can/does lower HR and BP and can cause dizziness...but if you have not increased your dosage and dizziness hadn't been a problem, I'd expect that medication did not directly cause the fall.
While I have AFib all the time, from what I read here I am lucky in that is doesn't have many symptoms I feel. Yes, I tire easily when doing physical work, just walking up a hill is hard, but I rarely feel dizzy and my rest HR is always under 100, and often in the 70s .. but still irregular due to AFib.
I am careful not to "jump up" from sitting or lying down both because of the need to "warm" my muscles up and to not get dizzy. That done, I'm fine.
You say you were letting your dog out, so I assume you'd been on your feet for at least a few steps when you suddenly lost consciousness - this being the case it may be time to get on a long term monitor again to see if you are having sudden drops in you HR.
oh,ouch. So sorry. With any rhythm that is way too fast (or way to slow), there is an emminent risk of falling on your head. It isn't coordinated enough to have a good pressure to support everything. BP is generally low. We don't even recommend getting up- unless absolutely necessary and then with help only. At that rhythm, it is time to get to a hospital and slow you down with iv drugs and convert you back into rhythm if possible. Hope they get that straightened out quickly.
You poor thing! I'm so sorry about your fall. Hopefully there was someone there to care for you. I have afib and yes, it does make me very dizzy when my rates are from 140 - 200 or more. During this time my BP drops and I get very dizzy and out of breath. I know when I'm in afib and when I am in it, I've learned to rise carefully from bed or from a seated position. If I start to black out I hit the floor and lie flat until my rate comes down.
I'm not sure about your drugs because I'm on Flecainide but I do know that when I was on Rythmol it caused my pulse and BP to drop lower than it should be but that was a constant problem until I switched drugs.
Hope you heal quickly!