What is Coronary Artery Disease and why does it happen?

So coronary artery disease is the buildup of cholesterol within the heart arteries. So for that to happen, you need a few separate conditions to occur. You need an initial, slightly unhealthy lining of the heart artery. So for the cholesterol to want to stick onto that segment of the heart artery, you've got to have a particular reason for that and that is because of damage or endothelial damage, so an unhealthy lining of the heart artery. Once you have that unhealthy lining, you have an area where the cholesterol will latch onto, so the cholesterol then sits on that unhealthy area of the heart artery and then over time that grows and what can make that worse is higher levels of cholesterol. So you can imagine if you have a low level of cholesterol, then it's less likely that cholesterol flowing through the blood vessel will then stick onto that unhealthy patch in the lining of the artery. Whereas if you have lots of cholesterol flowing through, it's much more readily available to then stick onto that area and grow. So I guess a few things that you then need to think about is what makes the lining of the artery unhealthy. Smoking is a massive one, absolutely massive. That really causes endothelial damage and makes the lining unhealthy, making it more likely for you to develop coronary artery disease. Other risk factors or traditional risk factors that we think of for heart disease is hypertension. So you can imagine if you have a high blood pressure, then there's an increased strain on the arterial walls. And that can also make the endothelial lining less healthy. and again, making it more likely for cholesterol to stick onto that area. Diabetes, of course, will also increase the likelihood of coronary artery disease by making the lining of the artery unhealthy, as well as altering the atherogenic properties of your cholesterol. So making the cholesterol itself more unhealthy. So the LDL levels and the HDL levels are important because they determine how much bad cholesterol there is floating in the blood, But beyond that, and subtly beyond that, you've got the fact that diabetes alters the property of an LDL molecule compared to a non-diabetic subject.