Hi ar bee,
It's funny - Jim and I were discussing this very thing yesterday!
Prior to his surgery he was only taking ramipril (ACE-inhibitor) to lessen the strain on his heart, stop his left ventricle from getting any bigger, and lower his blood pressure. The surgeon and his registrar gave us the impression he wouldn't need it after surgery. Obviously he's on warfarin because he has a mechanical valve, but they also kept him on ramipril too "for now". Then he was admitted to A&E a month after surgery with SVT (supra-ventricular tachycardia - an abnormal, rapid regular but not life threatening rhythm). At this point he was also prescribed beta-blockers to keep his heart rate down and stop any further episodes of SVT.
Our understanding was that abnormal rhythms are common in the first few months after OHS, and so we assumed he'd be taken off the beta-blockers after that time. He had a few moments where his heart beat fast for a few beats up to about 4 weeks after the emergency hospital admission, all of which happened before his post-op appointment with the cardio, but he's had none since we saw the cardio in February. The impression the cardio gave us though was that he had no intention of stopping either the ramipril or beta-blocker.
Jim's starting to think he'll be taken off them when he next sees the cardio, but I'm not so sure. He had a 24-hour ECG done a couple of weeks ago, maybe if that shows no irregularities he'll have a better chance of convincing the cardio he doesn't need the drugs. Unfortunately the cardiologist's opinion seems to be that if you don't have any problems while taking medication it must be working, rather than considering there may be no problem to medicate!!
Oh, incidentally, he (the cardio) also said the reason for continuing ramipril was that it has made Jim's left ventricle go back to normal size since the surgery. Kind of makes you wonder why he had the valve replaced if it's only the ramipril that's done that.
Not sure if this has helped answer your question, just thought I'd share our experiences!
Gemma.