The trial was terminated early for futility

So reported the leaders of another study of a promising medical technique, this time using arterial grafts to bypass blockages in the internal carotid artery. You might think that if the carotid is largely blocked by a clot big enough to be visible to MRI, and you use a graft to improve blood flow past the clot, this would improve blood flow to the brain and lead to fewer strokes. No such luck. Patients who received the surgery had more strokes than the control group.

Attempts to prevent heart attacks by bypassing blocked arteries have also failed.

Nobody knows why, but the underlying reality seems to be that our bodies are so complex and all the parts are so strongly interrelated that simple surgical interventions are like randomly unplugging wires in a malfunctioning computer.