#258 - AMA #48: Blood pressure—how to measure, manage, and treat high blood pressure

Hey everyone. Welcome to a Sneak Peek, Ask Me Anything or AMA episode of the Drive podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to Peteratti amd.com subscribe so without further delay, here's today's Sneak peek of the Ask Me Anything episode. Welcome to Ask me anything episode 48. I'm once again joined by Nick Stenson. In today's episode, we will focus on one topic, and that topic is blood pressure. If you listen to this podcast, you have heard me talk quite a bit about cardiovascular disease, and usually when I'm doing so, I'm doing so in the context of talking about prevention vis a vis apob and lipoprotein manipulation. But you've probably also heard me talk about blood pressure, because high blood pressure, along with high apob and smoking, is one of the three leading causes of atherosclerosis. What's perhaps most insidious is that many of you listening to this don't actually realize you have high blood pressure. And we therefore kind of begin the discussion by talking about what high blood pressure is, how common it is, and how you go about measuring it. It turns out that the measurement you get in the doctor's office is probably not that accurate for multiple reasons, which I go into in this episode. So what's most important for anybody who really wants to get under the hood of their own blood pressure is that you get a cuff and you figure out how to do this at home. Now, this can be done with an automated cuff or a manual cuff, and we'll talk about both of those. But it's really the way in which you go about doing this and the repeatability of the measurements and the time you take to do it that determines whether or not you can make the diagnosis of high blood pressure. We then focus on what to do about it, and this is where I think the most important part of the discussion takes place. How much does weight loss? How much does exercise? How much does nutrition? How much do any of these things tweak blood pressure, and if they still fail to do so, what are the pharmacologic choices you have and how should you be thinking about them? This is an extremely important topic, not only for cardiovascular disease, but also for dementia. And when you think about the prevalence of those two conditions, I think you'll understand why knowing your blood pressure is simply A non negotiable. And if your blood pressure is elevated, it has to be addressed. One last thing to note is that this is an audio only ama. There's no video for it. However, the show notes will include any figures and studies that I've discussed here and then some. So without further delay, I hope you enjoy AMA number 48.

Peter, welcome to another ama. How you doing?

Very well, thank you.

Awesome. You know, before we get started on this one, some of the people who listened to one or two AMAs ago, when we were going over your DEXA results, we were talking, telling the story about Reese's Pieces and how you had never heard of them. And we did a call out to say, hey, if anyone else has never heard of them, please reach out. And you will be pleased to know we probably had about 30 to 40 people who were in the same boat as you and had no idea what Rhys's PCs are. So you are not the only one.

Not the only one on this planet.

Not the only one. I mean, again, 30 to 40 compared to our listenership is not a good percentage. So you're definitely in the minority. But yeah, shout out to everyone who reached out and the person who was the first to reach out. We have something special going in the mail for them and ironically they reached out to us before we even sent the email saying the podcast was live. So to say they are an active listener would be an understatement. So shout out to that person, they know who they are. Today's AMA is going to be on one subject, but one important subject, which is blood pressure and all things blood pressure. And people who have listened to the podcast will have heard us talk about blood pressure before. Most recently, the episode we released with you and Ethan Weiss, Ethan coming back for the second time, you both spoke a lot about blood pressure. And as you said in that one, if you look at cardiovascular disease, three main risk factors for cardiovascular disease are going to be smoking, which we don't necessarily talk a lot about because as you've said before, we're kind of under the oppression. If you listen to this podcast and you still smoke, you probably should know you shouldn't. So that's nothing really we need to say there. The second is apob, which clearly is a topic that we cover a lot and has been covered. And then the third is blood pressure and we kind of realized we hadn't done as much of a deep dive on blood pressure and we get a lot of questions, so we compiled all those. And in today's AMA we're kind of really going to talk about a few different sections, multiple questions in each section, which is, what is high blood pressure, low blood pressure, why should someone care? You know, what does it affect? Because it goes beyond just the risk of cardiovascular disease as well as, you know, how do you know where you're at? This is one where you know, unlike Apob, you can't give yourself an at home blood test, but you can check your blood pressure and you can understand how it changes throughout the day, what the different definitions mean. And then we'll end with really the main focus, which is, okay, what can you do to control your blood pressure? You know, what are the lifestyle factors that you can do to lower it? How well do those work? If you have to look to use medications, what are the most common drugs? What do we know about them? Are there factors that would make one quote unquote better than the other? So that's really going to be our focus for this ama. And just given the importance of the topic and how many questions that we get on it and what we compiled, we figured we would just focus the entire thing on it. So before we start rolling on it, is there anything else that you want to add to set the stage?

No, I think that's a good way to land.

I think presumably most people who listen to this podcast have had their blood pressure measured at least some point in their life. Obviously, when you go to a doctor's office, even if you're going for anything random, they'll typically check it. A lot of people will have at home cuffs that they may be checking. So I think a lot of people have had their blood pressure measured. But I think it might be helpful to know, like, what does a blood pressure measurement actually mean? Like, what is it actually doing and measuring?

To understand that, you have to sort of think about what the heart is doing. So the heart is pumping, obviously that's what you feel if you put your hand on your chest. And what you're feeling is kind of the pulsatile sensation of the pressure difference in the arteries as the heart contracts. So just remember there's two phases of the cardiac contraction. The first is called systole. And systole is when the ventricles are contracting. The ventricles are the larger chambers, the left one being the muscular one, because it has to pump the blood against the, the systemic resistance of the whole body. And it's the one that's responsible for getting blood out to the body. We're going to talk about that pressure today. So we're going to talk about the systemic circulation. What we're not going to talk about today is a different blood pressure, which is pulmonary blood pressure. It turns out that when people hear like 120 over 80 is my blood pressure, that is talking about the blood pressure in their circulatory system of the periphery. But if you wanted to know the blood pressure in your lungs, which is controlled by the right ventricle, those would be pulmonary pressures, and those would be significantly lower. Again, we won't talk about those. Just park that over the side. So when your left ventricle contracts, you're in systole. Blood is leaving the heart through the aortic valve, goes out the aorta, at the ascending part of the aorta, and then it immediately just starts moving to the rest of the body, Right? So at the arch of the aorta, it jumps off three little freeways, if you will. So you have the common carotid subclavian and innominate arteries, and then it kind of goes over the arch, comes down, and then it goes out to the rest of the body. And this is happening really quickly. Even if your heart is beating as slow as one beat per second or 60 beats per minute, think about the rate at which that happens. I think everybody kind of understands that part. So there's a pressure in the artery that is experienced by literally the blood pushing against the walls of the artery during that phase. And that's obviously the bigger number. But it's important to remember that there is a second, equally important phase of the heart, which is the relaxation of the ventricle. And that's how they fill. So that's called diastole. So after the heart squeezes and blood leaves the heart, the heart has to relax to have blood come back into the ventricles through the atria. By the way. It's also important to know that this is when the heart itself receives its blood supply. So the heart receives its blood supply during diastole, whereas all the other organs are receiving their blood supply during systole. And even though the pressure in the arteries is lower during diastole, which I think would be intuitive given what I just described, it's still more than zero. There is still a tonic amount of pressure within the artery wall. So when you have your blood pressure checked and it spits out two numbers, let's just say it's 125 over 79. What that means is when your heart is doing the squeeze and there's a greater force as blood is leaving the aorta, the left ventricle via the aorta. It's whatever number I said, I already forgotten. I think 124 millimeters of mercury is the pressure. And when that ventricle relaxes and begins to fill through the left atrium, the pressure drops to. Whatever else I said, I forget. I think I said 79 millimeters per mercury. So millimeters of mercury is. I'm not going to get into what those numbers mean and how you do that. But, you know, if anybody thinks back to, like, a chemistry class, you can have a manometer that basically determines pressure by how many millimeters it can raise mercury. So the higher that number, the higher the pressure.

Does it ever blow your mind when you think about what the human body does on a daily basis that we don't even think about or see? Like, as you were saying, Even if it's 60 beats per minute, which is one beat per second, like, it's just constantly doing it. You've seen bodies cut open from your time in surgery before, so it's like you see that more. But does it ever just kind of blow your mind how we're able to function and we just don't even think about those little things every day?

It still does. It's been, I think, back to my very first time in the anatomy lab or my very, very first time being in surgery, and it's no less amazing to me today than it was then. I simply can't believe it.

The next question then, naturally, is, what does it mean to have high blood pressure? Because I think this is something that it seems like in the past five or 10 years, the definitions may be changed, and there's a few different types of definitions. So I think it'd be helpful to set the stage early of, you know, when we say high blood pressure, what are the two numbers that we're referring to? So people can kind of, as they look back at their own blood pressure results, can kind of know where they fit.

Well, as you said, this has changed a little bit. So prior to 2017, we had a little bit more leeway in the system. But the current updates, which have been in place for about six years and which were updated after the Sprint trial in 2015, a trial that I'll explain in a moment. Leave us where we are today. And where we are today is normal blood pressure is defined as having a systolic blood pressure at or below 120, or technically below 120 millimeters of mercury over something less than 80 millimeters of mercury. So if blood pressure is both less systolically than 120 and diastolically 80. That's considered normal. So 11979 normal. 12179. Technically not normal. Elevated is when the systolic pressure is between 120 and 129, but the diastolic pressure remains less than 80. So we talk about elevated blood pressure as a slight elevation in the systolic, but not the diastolic pressure. And then we get into two stages of hypertension. The first stage is when systolic blood pressure is 130, somewhere between 130 and 139, or diastolic blood pressure is between 80 and 89. So does that make sense? Because you'll notice there's a bit of a gap in there, right? So you could be 12083 and now you're at stage one even though your systolic is normal. And then stage two hypertension is when either systolic exceeds 140 or diastolic exceeds 90. So again, in summary, normal blood pressure is less than 120 and less than 80. Elevated is 120 to 129, over less than 80. Stage 1 hypertension is 130 to 139 or 80 to 89. Stage 2 is greater than 140 or greater than 90. Okay, so where do these numbers come from? Cause these aren't just arbitrary, right? These are sort of based on something important. And that something important is called the Sprint trial. This is a trial, I think it was published in 2015. It was like, I think it was like about a year or two before these guidelines were shifted. And the purpose of this trial was really to ask the question, what is the benefit of, for lack of a better word, aggressive blood pressure control. So the study looked at just under 10,000 people who had a systolic blood pressure of 130 or greater who were also at advanced cardiovascular risk, but who did not have type 2 diabetes. And the reason for that patient selection is you wanted a group of people who were at high enough risk for ASCVD that you could start to see events in a relatively confined period of time. You have to remember this is always the goal of clinical trials. Even when you're doing large double blinded trials, you want to be able to have enough events in the trial that you don't have to run the trial for 10 years. So you've got a high risk population. Though it's worth noting they don't have type 2 diabetes and they have to have A systolic blood pressure over 130. So they were randomized into two groups. The first group, which we'll call the intensive treatment, was treated to a systolic blood pressure of less than 120. And the standard treatment were treated to a blood pressure of less than 140. Makes sense. So one group is kind of being treated to not be over 140. The other group was really being pushed down to 120. So at coming in, the average blood pressure of all comers was about 140 over 78. Now, Ethan and I talked about this a little bit, but just in case folks didn't hear that podcast, or just in case people need a little bit of a refresher, is this study did a pretty rigorous job of assessing blood pressure. So they used an office visit where blood pressure was measured three times using the following protocol. So the patient would sit down for five minutes doing nothing, not talking, not. Not doing anything. Their back is supported, their legs aren't crossed. After five minutes, blood pressure was taken with an automated cuff. This was sized properly and used in perfect, correct way, which we'll talk about.

In a little while.

Later in this podcast, they would take that reading. Five minutes later they would repeat that. And five minutes later they would repeat that. So the blood pressure for that visit was deemed as the average of all three of those readings. And this is a lengthy procedure. Right. It took 15 minutes to get those three readings and to determine their blood pressure. But that number served as your blood pressure. So if you were on day one, you were 137 over 81 and you had that reading. Well, if you were in the business as usual group or the placebo group, or not the placebo group, but the standard treatment group, they would make no adjustment to your medication if you were already on medication. If you were not on medication, they wouldn't add medication, but if you were on the intensive group, they would treat you. So at one year, after one year of this, the average systolic blood pressure in the intervention group, the high intensity group, was 121.4 millimeters of mercury. In the standard group, it was 136.2. This intervention was stopped early. I forget how long they wanted to run this study for. I think they were looking to do this for five years. I could be mistaken on that. But regardless, at just a little over three years in median follow up, the study was halted. And this is not uncommon in hard outcome studies. We see this quite often where the benefits in one of the arms is so much greater that it becomes unethical to continue the study. And that was the case here. So the primary outcome, which was a composite outcome of reduction in cardiovascular mortality was significant. It was about a 25% relative reduction. So the hazard ratio is 0.075 and the absolute risk difference was about 0.54% over the course of one year. That's actually pretty significant. By the way, it doesn't sound like a lot, right, 25% reduction, a little over half a percent absolute risk reduction. But you have to remember that's a single year reduction in risk. That's quite significant when you consider that blood pressure, just like lipids, are compounding risk factors. At the three year mark, the total event rate was, I believe in an unadjusted way, I want to say 1.6% lower in the intensive group. And again, this was for this primary outcome. So which is a composite outcome. It was kind of a mace like output. So it was myocardial infarction, non myocardial infarction, acute coronary syndrome, stroke, acute heart failure and cardiovascular death. What I found pretty interesting about this study was that it also saw a benefit in all cause mortality. I would not have necessarily expected this. So I don't think it's that surprising that they saw a benefit in the primary composite outcome which really all pertained to heart attacks and strokes. It's maybe a little surprising how big the benefit was in such a short period of time. But what I think really caught people off guard in a pleasant way was that all cause mortality was also reduced 27% and it was like a 1.2% absolute risk reduction. This is pretty interesting. It's not that you wouldn't expect the death rate to be improved from a cardiovascular disease standpoint, which it was. Right. It was a 2x reduction in cardiovascular disease death specifically. But it's that you would see also a reduction in all sorts of other types of death. And this was seen in, you know, not surprisingly perhaps kidney disease. Amazingly accidental death, suicide, homicide was significantly less. So again, it's possible that maybe a larger study that wouldn't pan out, maybe a hundred thousand people, you wouldn't have seen that. But nevertheless, this was about as dispositive a study as you're going to see demonstrating the efficacy of aggressive blood pressure lowering. And again, the takeaway is, even over a relatively short period of time, aggressive blood pressure management to a systolic pressure less than 120 compared to standard of care, which we used to think was kind of 130 to 140 is tolerable. Left very little ambiguity about the importance of that kind of recommendation to double.

Click on something you said, because I think it is important and we've talked a little bit about it. When you've talked about statin therapy before, which is the percentage that we saw in this trial over the 1, 2 and 3 year mark, you kind of mentioned that that can compound over a lifetime. And so if you saw that much of a difference in a short period of time, it only gives you more confidence because the reality is if someone goes with high blood pressure for most of their life untreated, you, you're not looking at only three years. You could be looking at from 35 to 75, you could be looking at 40 years. And obviously you can't run a 40 year trial. And I know you've talked about this before with statins when I can't remember which study came out and I remember you saying the stock went down because people thought the result would have been even more positive. But you were kind of talking about if you look at how short that period was and how long people live with high APOB or high blood pressure, even though this was a short period, it still gives you even more confidence that this is something that people should take seriously even at a young age, even if it's not going to kill them in a year.

Yeah, compounding is insanely powerful when it comes to this type of biology, whether it be smoking, APOB or blood pressure. When we're dealing with endothelial exposure. Again, let's just take a step back and talk about why these things pose such a risk. Ascvd, cerebrovascular disease. You know, you can think of them as blood vessel diseases and elevated blood pressure. Hypertension is a mechanical disruption to the endothelium. Smoking is a chemical disruption to the endothelium. And of course APOB is the concentration of the lipoprotein that itself goes through that disrupted endothelium and then causes the pathologic sequence of events that we're very familiar with. So it's not surprising that these are all area under the curve problems when.

Talking about normal blood pressure, elevated blood pressure, high blood pressure. In the past, when we've talked about HBA1C, you've kind of mentioned before, you know, like, pre diabetes is about 5.7%. I think diabetes is about 6.5%. And you said like, hey, if you're at 6.4% and so you're not technically at having the diabetes level does that mean like you should celebrate? It's like, no, the difference between those is so small that you want to take care of it earlier. And so you've always kind of talked about one that's kind of why you don't like the A1C metric and you look at other things. But two you always kind of want lower is better when it comes to blood pressure. If someone has, let's say 119 over 78, so they're in the normal category, but there may be kind of creeping to the elevated category. If that was your patient, would you be worried about that or are you happy with any blood pressure in the normal category?

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Sam.