News & Perspective

Target of blood pressure control in the light of new ACC/AHA guidelines

Cardiology
4 months ago, OP Editor

Controversy over blood pressure treatment recommendations has been brewing since the release of the updated American College of Cardiology (ACC)/American Heart Association (AHA) hypertension guidelines in November 2017.1,2 At the conference of Advances in Medicine (AIM) hosted by the Chinese University of Hong Kong (CUHK), Dr. Chan Kwok-Keung, consultant cardiologist at the Pamela Youde Nethersole Eastern Hospital, shared his perspectives towards adopting the new guidelines in local practice.

The primary change in the 2017 guidelines includes a new classification system, with threshold of hypertension being lowered to ≥130/80mmHg (stage I hypertension), while patients with ≥140/90mmHg (the old definition of hypertension) is classified as stage II hypertension.1 Patients with blood pressures of 130-139/80-89mmHg would still receive nonpharmacologic treatment, unless they have a 10-year atherosclerotic cardiovascular disease (ASCVD) risk of 10% or higher; in that case, a single antihypertensive agent together with lifestyle modification is recommended.1

While the intention behind these changes is good, Dr. Chan pointed out that several professional societies, including the Hospital Authority, the World Health Organization, the American Academy of Family Physicians, the European Society of Hypertension and the European Society of Cardiology, continue to follow the old definition of hypertension.

A central part of the debate is whether the new guidelines went too far by creating a new level of disease which affects people previously deemed healthy. “What is now called stage 1 hypertension was previously defined as prehypertension, a term meant to alert physicians to provide prompt lifestyle education. With this new concept of hypertension, the prevalence of hypertension in the United States is estimated to increase from 32% to 46%,” said Dr. Chan. It is noted that the prevalence of hypertension in Hong Kong was 27.7% among persons aged 15-84, with 47.5% of them being undiagnosed before the Population Health Survey.3 “This may overburden our primary care physician workforce. Proper blood pressure measurement is critical but time consuming,” said Dr. Chan. “An unintended consequence would be overtreating low-risk patients with blood pressure-lowering medications in the real-world [practice].”

Dr. Chan also raised concern regarding the one-size-fits-all blood pressure goal, especially in the elderly population. “The new guidelines suggest a target systolic blood pressure of <130mmHg to those who are ≥65 [years old], non-institutionalized, ambulatory, community-living as a surrogate of ‘biological young’, but this may not be applicable in other countries such as Hong Kong, where ‘biological old’ patients are still living in the community,” he explained, and acknowledged that achieving that goal may be difficult for many elderly people. “Other international guidelines, such as those released by Eighth Joint National Committee (JNC8) in 2014 and the French Society of Hypertension in 2014, actually recommend a treatment goal of <150/90mmHg to patients who are ≥60 and ≥80 years old, respectively.”

Although the new ACC/AHA guidelines emphasize individualized cardiovascular risk assessment, the risk estimator (ACC/AHA Pooled Cohort Equations) has been criticized for not testing on randomized controlled trials, and without proof that it improves outcomes.2 “Even in the SPRINT study, the trial that heavily influenced the AHA/ACC guideline recommendations, high-risk patients were defined as having a 10-year risk of cardiovascular events of ≥15% as indicated by their Framingham risk score (FRS). This roughly translates into a 10-year risk of ~6-7% in the ACC/AHA Pooled Cohort Equations, implying that this risk calculator overestimates risk to an even greater extent than the FRS,” said Dr. Chan, and noted that It is also questionable whether an equation that was developed based on an old cohort of Caucasians and African Americans would be relevant to Asians.

To conclude, while a blood-pressure treatment target of less than 130/80mm Hg makes sense for high-risk patients, it remains debatable whether such a broad-brush approach should be adopted for everyone else, especially for low-risk patients.

  1. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. J Am Coll Cardiol. 2018;71(19):e127-e248
  2. Bakris G, Sorrentino M. Redefining Hypertension — Assessing the New Blood-Pressure Guidelines. N Engl J Med. 2018;378(6):497-499.
  3. Report of Population Health Survey 2014/2015. Department of Health. 2017 (Accessed June 6 2018, at https://www.chp.gov.hk/files/pdf/dh_hps_2014_15_full_report_eng.pdf).

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