Hi, cheer up! If your husband does what the doctor says, he can live a long life.
Here's some data for ya:
Success rate of coronary artery bypass graft surgery
About 90% of patients experience significant improvements after coronary artery bypass graft surgery. Patients experience full relief from chest pain and resume their normal activities in about 70% of the cases; the remaining 20% experience partial relief. In 5–10% of coronary artery bypass graft surgeries, the bypass graft stops supplying blood to the bypassed artery within one year. Younger people who are healthy except for the heart disease do well with bypass surgery. Patients who have poorer results from coronary artery bypass graft surgery include those over the age of 70, those who have poor left ventricular function, or are undergoing a repeat surgery or other procedures concurrently, and those who continue smoking, do not treat high cholesterol or other coronary risk factors, or have another debilitating disease.
Long term, symptoms recur in only about 3–4% of patients per year. Five years after coronary artery bypass graft surgery, survival expectancy is 90%, at 10 years it is about 80%, at 15 years it is about 55%, and at 20 years it is about 40%.
Angina recurs in about 40% of patients after about 10 years. In most cases, it is less severe than before the surgery and can be controlled by drug therapy. In patients who have had vein grafts, 40% of the grafts are severely obstructed 10 years after the procedure. Repeat coronary artery bypass graft surgery may be necessary, and is usually less successful than the first surgery.
Okay, so as you can see from the above information, recurrance is possible, because bypass surgery doesnt' cure the disease. It fixes the diseased 'parts', but the disease itself is still active, and so it can recur. Your husband's best bet is to obey the doctor's post op advice: usually it's eat healthier, exercise appropriate to your condition, lose weight if needed, limit alcohol to one/day, quit smoking and drugging if that shoe fits, manage stress (regarding stress, I like to ask myself, 'is this a big problem or a little problem? and most problems are little'), and TAKE YOUR MEDICATIONS. Also, treat depression. I WILL USE ALL CAPS TO STRESS THAT THESE THINGS ARE NOT OPTIONAL. THEY WILL DRASTICALLY PROLONG YOUR HUSBAND'S LIFE. If he is willing to do these things, he can live for a long time to come. I know you're both scared, but try and think positive. We all die, it's just a matter of how and when. So live for today, and take care of your health as listed above to better your chances of being here tomorrow and next year, next decade. That's all either of you can do. I know it's a drag. My husband is 8 years post op bypass surgery and he's in bad shape. Why? He never quit smoking, eats bad, sits around, has no stress management skills, and never took his meds. I think it's cost him some years. Not days, not months, years. I know he would be a lot better if he chose to take care of himself. Read the stats above. So the bottom line is there's no magic bullet, and you both need to learn to live with acceptance of this disease and then manage it smartly, wisely, and with daily diligence. You and your husband's longevity and quality of life will be worth it!
Best wishes!