Practice in Toronto, and with my Center, Cardio, Surgeon, etc., is generally to wait 6-8 weeks before starting cardio rehab. My Cardio put my name in to the rehab clinic at 6 weeks, and they called me at 7-ish. But I was heading off to Whistler for a week of downhill skiing (first ski day was today!) so we had to postpone 'til I'm back, at ~9.5 weeks.
Meanwhile, at 8-ish weeks, I just started skiing again -- with a newish heart-rate monitor and a brand-new ski helmet, and an extra neoprene "back belt" around my upper chest, for extra padding in case I land on my sternum area(and the heart-rate monitor!).
The ski day was nothing like my “normal” — much shorter "bursts" with much longer pauses in-between, and a short day, too — but it was great. We skied about 10,500 vertical feet, starting at almost 2 PM by the time we got everything sorted out. (Buying my first ski helmet was part of the morning’s business.) That’s about half of what I normally consider a minimally “accomplished” day, but it was plenty for today.
I used the heart-rate monitor, strapped around my chest, with the readout on a watch, to calibrate my feelings of (over-)exertion with my actual heart-rate. My post-op resting heart rate is way higher than pre-op, ranging from ~85 to ~105 most of the time (vs. 60 or lower pre-op). Skiing today, I got up over 130-ish a few times by the time I stopped (or soon afterwards), though I tried to keep the peaks lower than 130. I usually waited until it came down to 110 before I set off again, though I started a smidge sooner toward the end of the day.
All groomed runs, more blues than blacks (both very different from "normal"), but still great! Toward the end of the day, my heart-rate seemed to be recovering more slowly, but so were my THIGHS! I have a feeling that my heart will be the same tomorrow (maybe a smidge better), but the thighs will be worse!
I am obviously "pushing it" harder than I have 'til now post-op. My "Going Home" post-op booklet suggested walking as the main (only) exercise, and keeping my heart rate below 120 max, and less than 20 bpm above my resting rate (whatever THAT is, since it varies so much when I'm sitting at a computer!). But that was geared at the first few weeks after discharge, and I feel much stronger and better now than I did then.
BTW, my heart surgeon said "have fun", my GP said "take it easy", and my Cardio said "you're nuts" and "Nobody who's on Warfarin should ever go downhill skiing." I hope the surgeon turns out to be right, but I'm just running the experiment. . .
BTW, I'm on Warfarin (target INR 2.5-3), baby Aspirin, and 2x25mg Toprolol per day -- the latter because of a very few short periods of A-fib post-op.