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High-Stakes Pressure

ILLUSTRATION BY EMMA VOUGHT

New guidelines take aim at hypertension to lower risk of cardiovascular disease

SUBJECT MATTER EXPERT: DANIEL LACKLAND, PH.D.,
A MEMBER OF THE EVIDENCE REVIEW COMMITTEE
FOR THE UPDATED GUIDELINES

BY KIMBERLY MCGHEE

On completion of this article, readers should be able to:

  • Describe the new cutoffs for stage 1 hypertension in the 2017 updated AHA/ASA guidelines and the role of cardiovascular risk in guiding therapy
  • Recognize the importance of home monitoring to the accurate measurement of blood pressure
  • Discuss how fixed-dose regimens can encourage patient adherence to therapy

Cardiovascular disease (CVD) is the leading cause of death in the U.S.: one in four deaths can be attributed to it.1 Of all the modifiable CVD risk factors, hypertension accounts for the most CVD-related deaths,2 including those caused by coronary artery disease and stroke. Thomas Frieden, M.D., former director of the Centers for Disease Control and Prevention, has said that improving blood pressure (BP) control could save more lives than any other single clinical intervention.

Healthy People 2020 has set a target to increase the number of hypertensive patients whose blood pressure is under control to 61.2 percent. According to most recent estimates, only about half (48.9 percent) of Americans with hypertension have their blood pressure under control.3 In an effort to improve those numbers and to target interventions at the highest-risk patients, the American Heart Association and the American Stroke Association published an updated set of hypertension guidelines in 2017,4 the first since 2003.

A new definition of hypertension

The guidelines modified the definition of hypertension for the first time since the late 1990s. Individuals with a systolic blood pressure between 130 and 139 mm Hg or a diastolic pressure of 80 to 89 mm Hg are no longer classified as “prehypertensive,” a category that has been discontinued, but instead as having stage 1 hypertension. The former stage 1 hypertension (≥140/90 mm Hg) was reclassified as stage 2. Due to this change in classification, the number of Americans with high blood pressure increased from 32 to 46 percent, meaning that almost half of all Americans are affected.

Treatment recommendations and goals

The modified classification is meant to encourage treatment of individuals with a blood pressure of 130/80 mm Hg or higher, who already have twice the risk of developing CVD. Most of these patients can be treated with nonpharmacological therapies and followed up in three to six months to gauge progress. However, patients with stage 1 hypertension at high risk for CVD, i.e., those with a history of CVD or a calculated risk of ten percent or greater of developing CVD in the next ten years, require pharmacological therapy and should be followed up within a month. To assess ten-year CVD risk, the guidelines advise use of the ACC/AHA Pooled Cohort Equations (http://tools.acc.org/ASCVD-Risk-Estimator/).5 Recommended first-line antihypertensive agents include thiazide diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and calcium channel blockers (CCBs).6

For patients with stage 2 hypertension (≥140/90 mm Hg) or for those older than 65, who almost always have at least a ten percent risk of developing CVD in ten years, a combination pharmacological therapy with two or more antihypertensive agents and a follow-up at one month is recommended. Using two classes of antihypertensive agents, such as a thiazide diuretic and an ACE or ARB, can more effectively lower blood pressure. As a general rule, however, physicians should avoid using two agents from the same class (i.e., beta blockers) or two drugs that act on the same mechanism (i.e., ACE inhibitors and ARBs), because such combinations may be less effective and even harmful.

Individuals with a systolic blood pressure between 130 and 139 mm Hg or a diastolic pressure of 80 to 89 mm Hg are no longer classified as “prehypertensive,” a category that has been discontinued, but instead as having stage 1 hypertension.

Patients with a systolic blood pressure of 180 mm Hg or higher or a diastolic blood pressure of 110 mm Hg or higher require immediate evaluation and prompt initiation of antihypertensive treatment.

In part because of the findings of the SPRINT trial that tighter control of blood pressure led to a 33 percent reduction in cardiovascular events and a 25 percent reduction in deaths,7 the new guidelines recommend that almost all patients, including those with comorbidities and previous CVD, be treated to a goal of less than 130/80 mm Hg (previously less than 140/90 mm Hg).

Side effects from medications and the need to take multiple medications several times daily can deter patient adherence to treatment. To address these issues, the guidelines recommend prescribing, when possible, medications that can be taken only once daily and combination therapies that, because they require smaller doses of individual medications, are less likely to lead to side effects. Ideally, combination therapies would be prescribed in a fixed-dose formulation (one pill that contains the correct dose of two or three medications) to lessen the burden on patients and encourage adherence. Adherence can also be improved with better communication between care members and patients between visits, for example via telehealth, to identify and solve problems.

For good measure

If blood pressure measurements, in tandem with risk assessment, are to guide treatment, they must be accurate. The blood pressure that drives treatment should be the average of at least two measurements taken at different sessions. Improper technique can result in inaccurate measurements that can trigger inappropriate therapies.

Accurate blood pressures can be attained using the traditional auscultatory method provided proper steps are taken. However, evidence is accruing that the use of automated oscillometric devices can improve the accuracy of blood pressure measurement, provided that they are accurately calibrated.8 These devices often take multiple measurements of blood pressure while the patient is seated alone in a room, achieving effortlessly some of the goals of the staff training required for proper auscultatory determinations.

Other barriers to accurate measurement include “white coat” syndrome, in which patients’ blood pressures are higher in the office than at home, and “masked hypertension,” in which patients’ blood pressures are higher at home than in the office. The former can result in unnecessary treatment, and the latter can mean that patients at high risk for CVD remain untreated or undertreated. At-home blood pressure monitoring using automated, well-calibrated devices can help clarify which of these patients require or are responding appropriately to treatment.9

Race and ethnicity

Blacks

In the U.S., blacks, particularly black men, have the highest burden of hypertension, and their hypertension, like that of Hispanic and Asian Americans, is less likely to be controlled than for whites. In non-Hispanic blacks, only 43.8 percent of men and 52.3 percent of women achieve control, compared with 53.8 and 59.1 percent of white men and women. Although rates of awareness and treatment in blacks are similar to those in whites, black men are far more likely to die as a result of their hypertension: 1 in 20 black men die from hypertension-related causes compared with 1 in about 52 white men. Blacks also have a higher incidence of nonfatal strokes, fatal strokes and heart failure than other populations, and those with an APOL-1 gene mutation are 4.2 times more likely to develop end-stage renal disease.10

Achieving a target blood pressure of less than 130/80 mm Hg in black adults, as in other populations, is likely to require two or more medications. In black adults, one of those agents should be a thiazide diuretic or a calcium channel blocker. Thiazide diuretics have been shown to better prevent hypertension than drugs that act on the renin-angiotensin system, such as ACEs, ARBs and beta blockers, in these patients.11 A single-tablet combination that includes either a diuretic or calcium channel blocker is recommended, as it lessens the burden on patients and is likely to improve adherence.

Other ethnic groups

Hispanics have very similar rates of hypertension control as non-Hispanic blacks (43.5 vs. 43.8 percent, respectively). Compared with blacks, Hispanics are much less likely to be aware of their condition and seek treatment. Although control rates are similar between Hispanics and non-Hispanic blacks, mortality rates are considerably lower in the Hispanic population (about 1 in 52 men and 1 in 69 women), slightly lower than mortality rates in whites. However, this is a highly diverse population and it is difficult to generalize risk. For example, Hispanics from Mexico and Central America have lower CVD rates than white Americans, while Hispanics of Caribbean origin have higher rates.12 Hispanic Americans have a high rate of comorbid CVD risk factors, such as obesity and diabetes.

Non-Hispanic Asians have some of the lowest rates of blood pressure control (39.9 percent for men, 46.9 percent for women). They have a higher incidence of ACE inhibitor–induced cough than other subgroups.

Treatment goals and recommendations for these groups follow those in the general population.

Older adults

There is a very high prevalence of hypertension in older adults: 77 percent for men and 75 percent for women aged 65 to 74 and 79 percent for men and 85 percent for women older than 75. Blood pressure is lower in women until their fifties but begins to rise thereafter. Randomized trials have shown that reducing blood pressure in those older than 65 decreases CVD and mortality without increasing the risk for falls or orthostatic hypotension.13 For this reason, the guidelines recommend that ambulatory, non-institutionalized older adults be treated to a goal of less than 130 mm/Hg, as in younger adults, but physicians should be cautious in prescribing combination regimens that could trigger orthostatic hypotension. For institutionalized seniors or those with serious comorbidities or limited life expectancies, the guidelines leave it to the judgment of the clinician, the patient, and the care team as to how aggressively to manage blood pressure.

Further reading

A full version of the new guidelines and further physician resources are available at http://professional.heart.org/professional/ScienceNews/UCM_496965_2017-Hypertension-Clinical-Guidelines.jsp. Learn more about the evidence-based M.A.P. framework for improving hypertension control through the AMA’s Steps Forward module at https://www.stepsforward.org/modules/hypertension-blood-pressure-control.

To watch a video interview with Dr. Lackland about the new hypertension guidelines, visit the Cardiology page at the MUSC Health Medical Video Center (MUSChealth.org/medical-video).

References

1. Murphy SL, et al. Mortality in the United States, 2014. NCHS data brief, no 229. Hyattsville, MD: National Center for Health Statistics. 2015. Available at https://www.cdc.gov/nchs/products/databriefs/db229.htm
2. Danaei G, et al. PLoS Med. 2009;6:e1000058
3. Healthy People 2020 [Internet]. Washington, DC: U.S. Department of Health and Human Services, Office of Disease Prevention and Health Promotion [cited 5/1/2018. Available at https://www.healthypeople.gov/2020 /data-search/midcourse-review/lhi.
4. Whelton PK, et al. J Am Coll Cardiol. 2017 Nov 7. pii: S0735-1097(17)41519-1.
5. Goff DC Jr, et al. J Am Coll Cardiol. 2014;63:2935-2959.
6. Law MR, et al. BMJ. 2009;338:b1665.
7. SPRINT Research Group. N Engl J Med 2015;373:2103-2116.
8. Leung AA, et al. Can J Cardiol. 2017;33:557-576.
9. Stergiou GS, et al. Hypertension. 2014;63:675-82.
10. Lipkowitz MS, et al. Kidney Int. 2013;83:114-120.
11. Cushman WC, et al. Arch Intern Med. 2000;160:825-831.
12. Guzman NJ. Am J Cardiovasc Drugs. 2012;12:165-178.
13. Williamson JD, et al. JAMA. 2016;315:2673-2682.