Irregular heart rhythms are common after bypass surgery, often due to inflammation from the surgery that resolves in a few days. Usually, such rhythms are not life-threatening, though it may prolong his hospital stay. It is unlikely that this will reuslt in the need for a pacemaker.
The developement of Arrhythmia after bypass surgery is not an uncoomon event. In some cases, the developed arrythmia can cause serious complications such as the developement of chronic bracycardia or tacycardia, and a pace maker may be needed. A current study is looking into the affects of revascularization before bypass surgeries to combat potential complications such as arrythmia, but results have not yet been produced. I would continue to schedual regular appointments with a cadriologist to keep an eye on this condition as well as other conditions that may develope.