Both bypass surgery and angioplasty are effective at treating coronary artery disease, but they have different benefits and risks. Bypass surgery is more effective at improving blood flow to the heart and tends to provide longer-lasting results, but it is a more invasive procedure with a higher risk of complications. Angioplasty is a less invasive procedure with a lower risk of complications, but it may not be as effective at improving blood flow to the heart and the benefits may not last as long.