and, doctor harlan krumholz is professor of cardiovascular medicine at the yale school of medicine.issen, what do the medications do that the medications on the shelves today don't do? >> ldl is the primary driver of coronary heart disease, the most important risk factor we can modify. we have great drugs like zocor and lipitor statin drugs, that are effective at lowering ldl cholesterol and preventing heart attack, stroke and death but not everybody gets an adequate response to those drugs. some people are genetically programmed, they have very high levels of bad cholesterol ldl, and don't get well enough with those drugs, and there are other people who are intolerant to have the drugs. so we've needed another class of drugs. these drugs are really powerful. they lower ldl anywhere from 50 to 70%, and that's added on top of the effects of the statin drugs. so they're very exciting, very powerful. >> sreenivasan: without getting too far into the weeds, in lay terms, how do they work? how are they different? >> they increase the activity of the receptors in the liver responsible for