How could HDL and LDL lead to coronary heart disease?

Atherogenic. High LDL and low HDL both promote the development and progression of atherosclerosis (hardening of the arteries) which is the cause of blocked arteries in chd.
HDL good, LDL bad. Hdl and LDL refer to high (or low) density lipoproteins. These are part of how the body transports fats and cholesterol in our blood. Hdl carries cholesterol to the liver to be broken down while LDL deposits cholesterol in the walls of your blood vessels, causing coronary artery disease and a host of other problems. The goal is to raise HDL and lower LDL for optimal heart health.