Risk factors for coronary artery disease

- So we know that coronary artery disease is when you get this build up of fatty plaques in different places in your coronary circulation, so, for example, I'm drawing in bits of this plaque, right? So bits of this atherosclerotic plaque building up in different parts of your coronary vessels, and these are going to cause coronary artery disease, right? These are going to lead to downstream pathologies, diseases like stable angina and acute coronary syndrome, so we know this is really bad, right? We don't really want coronary artery disease to be happening in our bodies, so is there anything we can do about this? Is there anything that we can do to stop or prevent these plaques from building up in our arteries? And, in fact, yes, yes there are somethings we can do, and we didn't always know that there was something we can do. Way back in the 1940s, I believe it is, the late 1940s, there's a study done called the Framingham Heart Study, and the Framingham Heart Study was pretty revolutionary. It showed that there were risk factors for it developing coronary artery disease, and, so, why is that revolutionary? Well, it means there's something we could potentially do to reduce the incidence of coronary artery disease, and that's really good because coronary artery disease is the leading cause of death of men and women in the U.S., so all this talk about risk factors. What exactly is a risk factor? Well, a risk factor is something that predisposes you to something else, so, for example, you could say that buying an iPhone six is a risk factor for not having very much money left in your wallet, or playing ice hockey against Canadians is a risk factor for losing the hockey game, if you're on the other team, but to bring it back to something more relevant, something like hypertension would be a risk factor for coronary artery disease because all of this stress that pathologically high blood pressure puts on your vessels would predispose you to developing coronary artery disease, so the Framingham Heart Study showed us that there are two major types of risk factors. Modifiable risk factors and non-modifiable risk factors, and this is, actually, really important. It kind of means we could do something, we could modify something about our lives to lower our risk of coronary artery disease, but the flip size is there are non-modifiable things too, so no matter what we do, we can't change these things about our lives, so let's take a look at the major ones, so what's an example of a non-modifiable risk factor? Well, age, age is a risk factor because you can't really change how old you are, and, so, in coronary artery disease for men being 45 years or older sort of puts you in a higher risk bracket than being younger than that, and for women it's over 55, and it's not like 45 and 55, they're not these magic numbers that all a sudden once you turn 45, on the day of your 45th birthday, you're just more prone to developing these plaques. It's just that by the time you reach about 45 in men and 55 in women enough time has gone by in your life for you to get a significant amount of buildup, so, again, I want to stress that atherosclerosis, the underlying, sort of, plaque forming process behind coronary artery disease, that's a chronic condition. It develops over a long period of time, and, so, once you hit abut 45 years old in men, 55 in women, that's been a pretty good amount of time for the plaques to have built up, and, so, immediately, you should have another question. I mean, if you look at what we just written down, right? Let me highlight this for you, but we say men have a higher risk after 45 years and females have a higher risk after 55 years, well, that's a pretty huge difference. That's 10 years. I mean, you think back to 10 years ago, and there was no such thing as an iPhone, I can't even imagine that, but, so, 10 years is a long time, and, so, why are men at a higher risk then? And, you know, the answer is a bit multi factorial. There's a couple of reasons. For example, men tend to have a less healthy cholesterol profile in their blood compared to women, and it's thought that the higher levels of estrogen that women have contribute to the better profile of cholesterol that women have, and another interesting reason might be that studies show that women tend to listen to their doctors more when their doctors recommend lifestyle changes, so the lower incidence of cardiovascular disease might be a reflection of that. So, what else is non-modifiable? Well, your family history, for example. If someone in your family, a first degree relative maybe, had coronary heart disease, or any other type of heart disease, you would probably be at increased risk of also developing heart disease, and there's nothing sort of magical about that. It's just that you'd share a lot of genetic material, and we know that coronary heart disease has a lot of genetic influence to its development, so one more non-modifiable one I'll touch on is ethnicity. For example, certain ethnicities are indirectly at higher risk. People of African decent tend to have higher rates of hypertension than people of non African decent, and hypertension is a really well characterized risk factor for development of coronary artery disease. O.K., so those are the major non-modifiable risk factors, but what are some of the modifiable risk factors? I mean, we know that coronary artery disease is not what we want. Well, what can we do about it? What exactly can we do to prevent it, or at least reduce the incidence, or reduce the development of it? What can we do? Well, there's quite a lot of things we can do, actually. I mean, none of them will necessarily completely prevent us from developing arteriosclerosis or atharomas, plaques, but, you know, if we know that there's something we can do, then let's do that, so let me make some room here, and I'll do them in different colors this time. I'll do the modifiable ones over on this side, so high blood cholesterol levels, especially LDL, the bad cholesterol, the so called bad cholesterol. We know that a huge part of development of atheroma, of these plaques is the build up of cholesterol in the walls and the damaged walls of blood vessels, right? So, it makes sense, well if I have more LDL, if I have more of this bad cholesterol, probably more of it is going to build up in the walls wherever there's damage, and that's what we see in the studies, so cholesterol, high levels of LDL cholesterol is one of the key risk factors, the key modifiable risk factors. High triglycerides, or high levels of fat, free fatty acids because high levels of certain types of fat, and I won't get into all the details now, but high levels of certain types of fat will increase levels of other enzymes that increase plaque formation, and I know that sounds a bit of a run around, but that's the mechanism that we understand, and, by the way, I'm saying high levels of this, high levels of that, but what I'm meaning is in your blood, so if you have high levels of LDL in your blood, high levels of triglycerides in your blood, that's what I mean, so just keep that in mind. What else? High blood pressure, or hyper tension, because we know that high blood pressure will damage blood vessel walls with sheer stress, right? The blood will sort of bang against the blood vessel wall with so much force that it causes damage to the blood vessel wall, and that's when the LDL cholesterol gets in there and starts the plaque buildup, right? So that's why hypertension, high blood pressure, is a risk factor. Now here's a big one. This is probably the biggest one, and it's cigarette smoking, and you've probably heard this already. You probably know that smoking damages your blood vessels and smoking is bad for you, but it really is really bad for you, and, so, it turns out that actually quitting smoking is the single biggest thing that you can do to prevent development of coronary artery disease, to prevent plaque formation, so the reason for this, right? Is because remember the whole underlying issue in the first place is when you get damage of the blood vessel wall, so you damage the wall, then the cholesterol can jump in there and have a big party, and create a huge plaque. Well, when you smoke a cigarette, you are injesting toxins, right? And the toxins will get into your blood, and they will directly damage your blood vessel walls, and you know we're talking about it in terms of it's relevance to the heart rate now, but it can happen anywhere in your body, right? And so cigarette smoking, these toxic substances will damage your blood vessels, and you will develop atharomas, so cigarette smoking is the single biggest risk factor, and I know it sounds like I'm going on and on and on about this, but it really is that important to cut that out, so that's that. So what's another big one? Another big one is diabetes, and I think that most of us know that diabetes sort of is a disease caused by excess sugar, excess glucose that's sort of floating around in your blood and sort of wrecking havoc on your different vascular systems, and one of the problems that diabetes causes is that it damages your blood vessels because what happens is the little glucoses that are all floating around unregulated in your blood, they bind onto the sides of your blood vessels, and they make them stiff and damaged. A process called glycosylation, and I hate to beat a dead horse, but do you know we've talked about how the blood vessel damage is what predisposes you, sets up coronary artery disease and plaque formation, and it's really the same sort of process after you get that blood vessel damage in diabetes, so these are the underlying modifiable risk factors, right? Because there is something we can do about our blood sugar, there's something we can do about our cholesterol, and same goes for our fats, and our blood pressure, and cigarette smoking, we can stop smoking, so these are really the underlying modifiable risk factors, but it terms of your lifestyle, and what can you do with your lifestyle other than these dietary changes is you can increase you level of physical activity. A reasonable level of physical activity, every week or every day, can dramatically reduce your risk of developing coronary artery disease, and that's because when you exercise, right, when you exercise you improve the levels of glucose in your blood, and you improve your cholesterol profile, and you use up a lot of your fats, and you lower your blood pressure, and you know just going by the numbers, by the statistics here, if you were an exerciser, than you're less likely to be a smoker, and so just by getting exercise into your week, you're all of a sudden reducing all of these modifiable risk factors for coronary artery disease, so if you're obese, or if you have a distinct lack of physical activity, then all of that plays in and increases your overall risk again on top of these other modifiable risk factors, so that's really all I wanted to say about non-modifiable risk and modifiable risk factors, but there is one more interesting, little tidbit that I have to drop on you. One of the reasons for acute coronary syndrome to happen is atherosclerosis, right? It's buildup of these fatty plaques, but another reason why you might get acute coronary syndrome is due to cocaine use, cocaine or amphetamine use, so I thought I'd just touch on why because this really is suppose to be both about coronary artery disease and acute coronary syndrome. What cocaine can do to your coronary vessels is it can cause them to vasospasm. Now vasospasm, what the heck does that mean? Well, it means that it causes your coronary arteries to clamp down and close off, and by the way I'm not writing cocaine in white for any particular reason in case you were wondering, just putting that out there, so that's obviously not going to let blood through, right? So, in that way it sort of approximates a plaque. It's similar to a plaque in that it can compromise blood flow downstream, and that's how it causes acute coronary syndrome, so that's probably another thing to not do.