No matter which hospital you choose, bypass surgery
always comes with risks. About 2% of patients die in the hospital or within one month of the operation. A study in 2001 found that about one in four patients developed cognitive problems that remained evident six months after the operation. Another recent study found that more than 7% of all bypass patients experience acute kidney
Some patients are especially likely to suffer complications. Patients in their 70s and beyond are automatically more vulnerable. The operation is also riskier for people who have an additional serious illness, such as diabetes
, or kidney failure.