Moderate to severe kidney problems can happen in 7 out of 100 patients who have off-pump bypass surgery. Mild complications can happen in as many as 20 out of 100 patients. Most of the time, these problems are temporary and the body recovers within about seven days. With temporary kidney problems and off-pump bypass surgery, there's usually no permanent damage. However, some patients develop serious kidney problems and may need lifelong treatment with kidney dialysis.