By Priya Umapathi, M.D.; Haitham Ahmed, M.D.; and Erin Michos, M.D., M.H.S.
What may be affecting your doctor’s decision to change your blood pressure target most recently is the landmark SPRINT study published in the November issue of the New England Journal of Medicine. But we’ll come back to that in a bit. Let’s first look at how blood pressure measurements came about and how blood pressure targets have changed over the years.
Blood pressure was first measured in animals in the 1700s by Cambridge scientist Stephen Hales using brass pipes and glass tubes. By the late 1800s, clinicians could measure blood pressure in patients, paving the way for the great debate on blood pressure goals. In the early 1900s, Mayo Clinic described a syndrome of “malignant hypertension,” which was characterized by very high blood pressure, damage to the back of the eye and initially adequate kidney function that later often resulted in death from stroke, heart failure or kidney failure.
Franklin Roosevelt, our 32nd president, was diagnosed with high blood pressure in the late 1930s. Unfortunately, his high blood pressure was ignored, even thought to be normal for a man his age. In 1945, at age 63, Roosevelt died from a sudden brain bleed. His blood pressure the morning of his death was greater than 300/190! Today, we consider less than 120/80 to be normal.
By the 1950s, the medical community at large was beginning to doubt the “benign” nature of high blood pressure, owing to the results of a number of studies. One of the largest of these, the Framingham Heart Study, demonstrated that high blood pressure increased the risk of cardiovascular diseases — including heart attacks and strokes — and even the risk of death. Since then, multiple professional medical societies, like the American Heart Association and the American College of Cardiology, have highlighted the effects of uncontrolled high blood pressure on health with direct links to heart attacks, heart failure, kidney disease and other medical conditions.
The first medical intervention for high blood pressure was the low-salt diet, coined the “rice diet” in the 1930s. More recently, this took the form of the DASH (Dietary Approaches to Stop Hypertension) diet. The DASH diet is not just a low-salt diet; it is an eating plan that also emphasizes fruits, vegetables, low-fat or nonfat dairy, whole grains, lean meat, fish and poultry. It limits sugar-sweetened foods and beverages, red meat and added fats. In addition to its effect on blood pressure, it represents a “heart-healthy,” well-balanced diet, and many people even lose weight when sticking to it. The National Institutes of Health sponsored the DASH diet clinical trials and found it to be effective in lowering blood pressure. Thus, lifestyle changes, such as diet and exercise, should always be first-line therapy for blood pressure control. Despite this, many patients still require more than lifestyle modification to control their blood pressure.
Early blood pressure therapies included using thiocyanate and ablating parts of the sympathetic nervous system in the chest. Ouch! Good thing plenty of safer therapy options exist today. Over time, medicine and pharmacology evolved, leading to one of the first well-tolerated blood pressure agents, hydrochlorothiazide. The first so-called water pill reduces blood pressure by causing urination and reducing blood volume. Shortly thereafter, our arsenal of medications expanded to other commonly used medications, such as beta blockers, calcium channel blockers and angiotensin-converting enzyme inhibitors. These discoveries are partially credited for reducing stroke and heart disease by 50 percent from 1972 to 1994.
High blood pressure is common in U.S. adults, especially among people older than 60, and it affects approximately 1 billion adults worldwide. Blood pressure is measured as the systolic blood pressure (top number) over the diastolic blood pressure (bottom number). Of the two, the top number is a more significant predictor for risks of heart disease, stroke, heart failure and end-stage kidney disease. The Global Burden of Diseases, Injuries, and Risk Factors Study examined 67 different factors for death and lost years of life due to disability over a recent one-year span, ultimately identifying elevated blood pressure as the leading risk factor.
Numerous clinical trials showed that treatment of high blood pressure reduces the risk of cardiovascular disease outcomes, including stroke by 35 to 40 percent, heart attacks by 15 to 25 percent and heart failure by up to 64 percent. However, the magic number or target blood pressure is still not known.
There have been a couple of numbers discussed over the last few years for an ideal blood pressure. As with many things, blood pressure is not one size fits all. Different goals for different groups of people exist that factor in age and other medical conditions, such as diabetes and heart disease.
A consortium of blood pressure experts, the Joint National Commission on Blood Pressure, issued its latest recommendations on the subject in 2014. The guidelines are based on four groups of patients: older than 60, younger than 60, all ages with diabetes but no kidney disease and all ages with kidney disease. For the latter three categories, the target blood pressure goal was less than 140/90 millimeters of mercury. The patients over age 60 had a little more wiggle room for an acceptable blood pressure at less than 150/90 millimeters of mercury. And that was the last word on the subject … until two months ago.
Now let’s get back to SPRINT. No, not the phone company — the Systolic Blood Pressure Intervention Trial. The trial compared the benefit of treating systolic blood pressure to less than 120 millimeters of mercury with treating blood pressure to less than 140 millimeters of mercury. Some take-home points from the study:
1. The Who
— More than 9,000 patients participated in this trial. Study participants were at least 50 years old, had systolic blood pressures between 130 to 180 millimeters of mercury and were determined to be at an increased cardiovascular risk.
— The researchers defined patients as having an increased cardiovascular risk if they were older than 75 years of age, had a history of coronary artery disease, had a history of chronic kidney disease or were estimated to have a greater than 15 percent risk for a heart attack over the next 10 years based on the presence of heart disease risk factors.
— They excluded patients with diabetes or prior stroke.
2. The Intervention
— They randomly assigned participants to either the intensive (treat to less than 120 millimeters of mercury systolic) group or the standard (treat to less than 140 millimeters of mercury systolic) group.
— Using common medications, including water pills, beta blockers and calcium channel blockers, the researchers aimed to attain the assigned blood pressure targets.
— Patients participated in monthly visits for the first three months and every three months thereafter to assess their blood pressure. Doctors adjusted treatments as needed to hit target blood pressures for each group.
— At each office visit, doctors took the average of three blood pressure measurements with the patient seated and after five minutes of quiet rest.
— The trial organizers planned for a five-year study but stopped early at a little over three years due to positive results.
3. The Good
— Fortunately, the risk of cardiovascular events, including heart attacks, strokes, heart failure or death, was low in both treated groups. Cardiovascular events occurred 1.7 percent per year in the intensive treatment group, compared to 2.2 percent per year in the standard treatment group. That’s approximately a 25 percent lower cardiovascular risk for people following stricter blood pressure controls!
— The intensive treatment group also had lower rates of several other important outcomes, including 38 percent lower risk of heart failure, 43 percent lower risk of death from a cardiovascular cause and a 27 percent lower risk of death from any cause.
4. The Bad
— As might be expected, treating blood pressure more aggressively comes at the price of more side effects. Problems with too-low blood pressure, such as fainting, blood electrolyte abnormalities or kidney damage, occurred more frequently in the intensive treatment group than in the standard treatment group.
SPRINT demonstrated additional reductions in the risk of major cardiovascular events through more stringent blood pressure control. That is very exciting news that likely will change recommendations for many patients. However, it is important to remember that not all patients are the same. In considering this data, we must be mindful of the population studied. Benefits seen in the trial group may not translate to everyone. Also, we must consider the consequences of low blood pressure, fainting or kidney damage. When considering their own patients, health care providers need to weigh the potential benefits and risks of a targeting a lower blood pressure goal; it’s a balancing act. This conversation should be part of a shared decision-making process between providers and their patients.
As we start the new year with new goals in mind, many patients may not be ready to sprint to the finish line. Blood pressure treatment is a long-term process managed over years, even decades — it’s more like a marathon than a sprint. A slow and steady reduction in blood pressure may be the way for all of us to end up as winners.
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Managing Blood Pressure: It?s a Marathon, Not a Sprint originally appeared on usnews.com
