This NY Times article reports on new studies that increasingly indicate that coronary bypass opearations and angioplasty procedures are not as effective in preventing heart attacks in high risk patients than non-invasive treatments such as giving up smoking and taking drugs to control blood pressure, reduce cholesterol levels, and prevent blood clotting. The research reflects that that just one of those treatments — lowering cholesterol to what guidelines suggest — can reduce the risk of heart attack by a third. However, only 20% of heart patients follow that approach. As the Times article notes:

But, researchers say, most heart attacks do not occur because an artery is narrowed by plaque. Instead, they say, heart attacks occur when an area of plaque bursts, a clot forms over the area and blood flow is abruptly blocked. In 75 to 80 percent of cases, the plaque that erupts was not obstructing an artery and would not be stented or bypassed. The dangerous plaque is soft and fragile, produces no symptoms and would not be seen as an obstruction to blood flow.
That is why, heart experts say, so many heart attacks are unexpected ? a person will be out jogging one day, feeling fine, and struck with a heart attack the next. If a narrowed artery were the culprit, exercise would have caused severe chest pain.
Heart patients may have hundreds of vulnerable plaques, so preventing heart attacks means going after all their arteries, not one narrowed section, by attacking the disease itself. That is what happens when patients take drugs to aggressively lower their cholesterol levels, to get their blood pressure under control and to prevent blood clots.
Yet, researchers say, old notions persist.
“There is just this embedded belief that fixing an artery is a good thing,” said Dr. Eric Topol, an interventional cardiologist at the Cleveland Clinic in Ohio.