**EP238: Oh No, Blood Pressure Again!!!**
**Dr. Ulrich Bishop:** Welcome to Dr. Warwick's podcast channel. Warwick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warwick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love.
Hi, my name is Dr. Ulrich Bishop, and welcome to my podcast and videocast station. Today, I'm going to jump on one of my soap boxes, and that's high blood pressure. Well, I have to confess I'm a little bit of a nerd in this space. Blood pressure, to a large degree, is fairly boring for most of my colleagues because it just doesn't have that adrenaline-pumping excitement of dealing with people who are having heart attacks, having funny rhythms, or having cardiac failure. Honestly, it does just come across a little bit bland.
But in the last years, I've become a convert. I think blood pressure is outrageously important. We don't feel it, so no one thinks about it. But it is the absolute foundation of the wear and tear on your vasculature and on your heart. The analogy I often use with people is that if you think of an irrigation system and then increase the pressure in that irrigation system, you may well see ruptured pipes. Well, that would be heart attack or stroke. Timing of the pump of that irrigation system? Well, that would be atrial fibrillation. The pump itself might pack up. That would be cardiac failure. And the filter within the irrigation system might fail as well. That's renal failure.
So blood pressure is directly linked to heart attack, stroke, atrial fibrillation, cardiac failure, and renal failure. Why on earth wouldn't we make it a priority to get it measured and managed properly, particularly when our medications work so well to bring it under control?
With that as a backdrop, let me tell you a little bit more about where we are with blood pressure in 2020. The guidelines are changing, and back in 2017, we used to be aiming for a systolic blood pressure of less than 140. That was the US and Australian guidelines. But more recently, the more up-to-date iteration of guidelines, both locally and internationally, have moved to a lower goal. And 130 is now the new 140. And that's pretty good. A 10 mm shift down would have a significant impact on outcomes.
We know that a five-millimeter reduction in blood pressure is on a continuum such that we get a reduction in major adverse coronary events of 10% for a simple five-millimeter reduction, which is just extraordinary. So current guidelines aim for less than 130, but I'm going to put to you it should be even lower. I try and run my blood pressure way down between 110 to 120. The reason why is that some recent data from a trial called the SPRINT trial, which looked at lowering blood pressure quite intensively with an aim at under 120 compared to standard therapy, took about 9,000 people, ran for three years, and demonstrated the following:
In the care group of the people who got their blood pressures under 120 mmHg, they demonstrated a significant reduction in composite cardiovascular and all-cause mortality. Their hazard ratio was 0.75%. This means that they are at a 25% less chance of having problems compared to the standard care group. This is back when standard care, by the way, was less than 140 millimeters of mercury. They were able to demonstrate that there was increased blood flow, decreased white matter loss, and decreased cognition. That points to blood pressure not only being linked to stroke, heart attack, atrial fibrillation, cardiac failure, and renal failure, but also dementia.
It demonstrated a reduction in chronic kidney disease. It had no difference in quality of life. Importantly, the people in the intensive group were often taking an extra medication to achieve that, but that extra medication didn't impact quality of life measurements. Lastly, there was no significant marker in terms of increased adverse events. So people didn't appear to fall over more, didn't appear to run into issues with low blood pressure in a negative way.
The SPRINT trial really tells us, to a large degree, that lower is possible, and we think about blood pressure as a continuum. So why wouldn't we drive it down to levels that really are as low as possible without causing side effects?
One of the things that I'm really a strong advocate of now is making sure that as part of a routine check, we get 24-hour blood pressure monitoring undertaken for patients. This 24-hour blood pressure monitoring is a cuff on the arm that you wear during the day. It takes your blood pressure every half an hour and hourly overnight while you sleep, but it gives us a beautiful profile and lots of data points so that we really know what your blood pressure is like over a 24-hour period.
This testing has recently become rebateable with a Medicare rebate in Australia, and I highly recommend it as a way to get the most precise information around where your blood pressure sits. It really helps us rule out that group of people who have, if you like, white coat or volatile hypertension, which can falsely lead us to the belief that their blood pressure is elevated. Check it out. Speak to your GP about it if you haven't had one done recently.
To be honest, if your blood pressure is up, I think it's also a really good idea to get an echocardiogram. That's an ultrasound of the heart. Because if your blood pressure is up, we can measure the thickness of the heart muscle and ascertain if it's responded to that increased blood pressure load. If it has responded and has become thicker, we would have an even greater intensity to try and lower your blood pressure into an appropriate range, as thick hearts are not necessarily good hearts. So, echo and 24-hour BP. Think about it.
I'm also going to let you know about some stuff which I'm pretty sure will turn up on the horizon pretty soon, and that is salt substitutes. There's a fantastic study done by one of our Australian researchers where they looked at salt substitution. They took about 20,000 people over a five-year period in rural China by adding a salt substitute. So instead of sodium chloride, our standard salt, they added in potassium chloride as that substitute.
What they demonstrated over the five-year period was an average reduction of blood pressure of three millimeters of mercury. Well, that doesn't sound like a lot, but remember I said to you before that a five-millimeter reduction in blood pressure has a significant effect on major adverse coronary events. Well, in this particular salt substitution trial, using potassium chloride instead of sodium chloride, that three-millimeter reduction in blood pressure reduced stroke incidence by 14%, major adverse cardiac events by 13%, and all-cause mortality by 12%. And that's just changing what salt you use.
This is incredibly remarkable information and does nothing but galvanize my resolve to be a blood pressure nerd and make sure my patient's blood pressure is well controlled. I'm going to invite you to make sure your blood pressure is well controlled. Talk to your GP about it. Get good data.
I didn't mention one thing which I also do mention to my patients whose blood pressure is elevated if they are carrying a bit too much weight. This is a really good equation for you to take home: If you carry a couple of extra kilos, what we know is one kilogram in weight loss leads to a one millimeter reduction in blood pressure. This is a fantastic payback on a little bit of weight loss. If you can get three to five kilos off, based on what I've shared with you today, you're getting 10 to 15% reductions in your risk of future problems in regard to heart, stroke, renal disease, and probably even dementia.
Well, I hope you enjoyed me dancing on my soapbox about blood pressure. Please look after yours. It's a silent killer, but we can do so much about it. Have the conversation with people. Make sure they're looking after their blood pressure too. If you've got any queries or questions, drop us a note at info at drwarwickbishop.online.
Do wish you the very best. Until next time, live as well as possible for as long as possible, and thank you so much for joining me.
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