If the narrowing is limited to a single artery, it may be possible to treat with an
angioplasty and stent, which is a very well established
procedure these days (I've had four stents). If multiple arteries are involved, artery bypass may be more appropriate, but again this is a very well established procedure with good recovery rates.
Finding a blockage or narrowing means you have coronary artery disease, as do millions of others.