“In the late 1930s, cardiac surgeons developed an innovative procedure to help those suffering from repeated chest pains due to severely blocked coronary arteries. The surgery consisted of making two incisions in the chest wall to tie off two unnecessary arteries that supply blood to the inside walls of the chest. Theoretically this could shunt extra blood flow back to the heart, thereby increasing flow through the hearts arteries and reducing chest pain. Initial reports indicated it was highly effective, and case studies showed success rates of up to 75 percent. For the next two decades the surgery became common, until the late 1950s, when two researchers studied the procedure separately and found strikingly similar results. The studies compared the surgery to a sham (placebo) procedure in which two incisions were made in the chest wall and then sutured without tying off the internal arteries. The studies showed the real surgery to be as successful as surgeons had believed. In the true surgery groups, 67 percent of patients showed major reductions in pain and in the need for medicine, and major improvements in the ability to exercise without serious chest pain. But the sham surgery was an even bigger hit: in the sham group 83 percent of patients showed the same improvements.”