This week, I’d like to discuss some of the nuances of hypertension, or high blood pressure, a contributing risk factor for heart disease. Hypertension affects approximately 33 percent of Americans, according to the latest statistics from the Centers for Disease Control and Prevention, and only 52 percent of these have it controlled (1). What could we possibly learn about blood pressure that we have not heard already? New information is always coming out about this common disease. Studies are teaching us about diagnostic techniques and timing, as well as consequences of hypertension and its treatment. Let’s look at the evidence.
When you go to the doctor’s office, they usually take your blood pressure first. But do they take readings in both arms and, if so, have you wondered why? I take blood pressure readings in both arms, and when one of my longtime patients asked me why, I joked that I need to practice. In truth, it’s because there may be significant benefit from taking readings in both arms.
An analysis of the Framingham Heart Study and Offspring Study showed that when the blood pressure was taken in both arms, when there was a difference of more than 10 mm Hg in the systolic (top number) blood pressure, then there may be an increased risk for the development of cardiovascular disease — stroke and heart disease (2).
This is a simple technique that may give an indication of who is at greater cardiovascular disease risk. In fact, when this interarm blood pressure comparison showed a 10 mm Hg difference, it allowed the researchers to identify an almost 40 percent increased risk of having a cardiac event, such as a stroke or a heart attack, with minimal extra effort expended.
So, the next time you go to the doctor’s office, you might want to ask if they would take your blood pressure in both arms to give you and your doctor a potential preliminary indication of increased cardiovascular disease risk.
When do we get our blood pressure taken? For most of us it is usually at the doctor’s office in the middle of the day. This may not be the most effective reading. Nighttime blood pressure readings may be the most accurate, according to one study (3). This was a meta-analysis (a group of nine observational studies) involving over 13,000 patients. Neither the clinical nor daytime readings correlated significantly with cardiovascular events when multiple confounding variables were taken into account, while every 10 mm Hg increase at night had a more significant predictive value.
Twenty-four ambulatory blood pressures readings were taken with these patients, which means these were standardized readings. Does this mean that nighttime readings are more important? Not necessarily, but it is an interesting finding. With my patients, if blood pressure is high in my office, I suggest that patients take their blood pressure at home, both in the morning and at night, and send me readings on a weekly basis. However, at least one of the readings should be taken before antihypertensive medications are taken, since these will alter the readings.
There has always been a debate about whether salt really plays a role in high blood pressure and heart disease. The latest installment in this argument is a compelling British study called the Health Survey from England. It implicates sodium as one potential factor exacerbating the risk for high blood pressure and, ultimately, cardiovascular disease (4). The results show that when salt intake was reduced by an average of 15 percent, there was a significant blood pressure reduction and that this reduction may be at least partially responsible for a 40 percent reduction in stroke mortality and a 42 percent reduction in heart disease mortality.
The graphs of sodium reduction mimicked the line graphs for the reductions in deaths from stroke and heart disease. One potential study weakness was that physical activity was not taken into account. However, a strength of this study was that it measured salt intake through 24-hour urine tests. Most of our dietary salt comes from processed foods that we least suspect, such as breads, pastas and cheeses.
Age-related macular degeneration
When we think of blood pressure-lowering medications, we don’t usually consider age-related macular degeneration as a potential side effect. However, in the Beaver Dam Eye Study, those patients who were taking blood pressure medications were at a significant 72 percent increased overall risk of developing early-stage AMD (5). It did not matter which class of blood pressure-lowering drug the patient was using, all had similar effects: calcium channel blockers, beta blockers, diuretics, and angiotensin receptor blockers.
However, the researchers indicated that they could not determine whether the blood pressure or the blood pressure medication was the potential contributing factor. In addition, another study actually suggests the opposite — that blood pressure medications may reduce the risk of AMD (6). However, this was a retrospective (backward-looking) study, and it has yet to be published.
This is a controversial topic. If you are on blood pressure medications and are more than 65 years old, I would recommend that you get yearly eye exams by your ophthalmologist.
As we age, falling risk seems to increase. One study shows that blood pressure medications significantly increase fall risk in the elderly (7). Overall, 9 percent of these patients on blood pressure medications were seriously injured when they fell. Those who were considered moderate users of these medications had a 40 percent increased risk of fall. But, interestingly, those who were consider high-intensity users had a slightly less robust risk of fall (28 percent) than the moderate users. The researchers used the Medicare database with 5,000 participants as their data source. The average age of the participants in the study was 80.
Does this mean that we should discontinue blood pressure medications in this population? Not necessarily. This should be assessed at an individual level between the patient and the doctor. Also, one weakness of this study was that there was no dose-response curve. In other words, as the dosage increased with high blood pressure medications, one would expect a greater fall risk. However, the opposite was true.
In conclusion, we have some simple, easy-to-implement, takeaways. First, consider monitoring blood pressure in both arms, since a difference can mean an increased risk of cardiovascular events. Reduce your salt intake; it appears that many people may be sensitive to salt, as shown by the British study. If you do take blood pressure medications and are at least 65 years old, take steps to reduce your risk of falling and have annual ophthalmic exams to check for AMD.
References: (1) CDC.gov/blood pressure. (2) Am J Med. 2014 Mar;127(3):209-215. (3) J Am Soc Hypertens 2014;8:e59. (4) BMJ Open 2014;4:e004549. (5) Ophthalmology online April 30, 2014. (6) ARVO 2013 Annual Meeting: presentation. (7) JAMA Intern Med. 2014;174(4):588-595.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.