Clinical guidelines are key to ensuring that consistent, best practice approaches are used to treat patients. One example is the guideline relating to high blood pressure (hypertension). The new 2017 ACC/AHA guidelines for hypertension are detailed and extensive, and cover all aspects of the patient care process, from diagnosis to management and patient monitoring. Professor John Flack and Dr Bemi Adekola, Southern Illinois University, summarise the main points of the guideline and highlight how it is different from other clinical guidelines. Using high quality, evidence based clinical guidelines allows clinicians to apply this knowledge to local practice and to optimise care offered to patients with hypertension.
Elevated blood pressure, or hypertension, affects an estimated 1.13 billion people worldwide. Hypertension is a major cause of premature death, as it can significantly increase the risk of other conditions such as heart, brain, and kidney diseases. It is caused when blood pressure, the force produced when circulating blood pushes against the walls of blood vessels, is too high. There are a number of modifiable and non-modifiable risk factors for hypertension, including lifestyle, diet, weight, genetics and age.
The World Health Organization reports that fewer than 1 in 5 people with hypertension have the problem under control. Alongside this, high blood pressure may not show recognisable signs or symptoms and is most commonly picked up through regular blood pressure (BP) monitoring.
Following diagnosis, the treatment for hypertension is an area that has evolved over the years. Importantly, focus has moved away from the use of one single drug to reduce cardiovascular disease risk, to considering a combination of patient characteristics and which drug, or combination of drugs, will lower BP to an optimum level.
One of the global targets for noncommunicable diseases (diseases that aren’t transmitted from person to person) is to reduce the prevalence of hypertension by 25% and to improve blood pressure control by 2025. Up to date, evidence based clinical guidelines, when effectively implemented, won’t substantively lower hypertension prevalence but will almost assuredly improve BP control rates.
The American College of Cardiology (ACC) and American Heart Association (AHA) task force on clinical guidelines published their latest report in early 2018. Dr John Flack and Dr Bemi Adekola are both members of the department of Medicine at Southern Illinois University. They have reviewed and summarised key points in this most recent expert guideline for the prevention, detection, evaluation and management of hypertension in adults.
The 2017 ACC/AHA guidelines
The 2017 ACC/AHA guidelines are used by many organisations and clinicians to inform and guide their development of local hypertension treatment algorithms.
The guideline covers a variety of aspects relevant to optimising medical management of hypertension. The guideline defines new BP categories and encourages at least two or more separate BP readings in most situations before diagnosing hypertension. The guideline also provides extensive guidance around how to measure BP accurately so that hypertension is not falsely diagnosed. Dr Flack explains that the algorithm for obtaining accurate BP readings is more extensive than the way BP is usually measured. Health systems and clinics, will, however, need to adapt a set of key elements required for accurate BP measurement to fit their local practice styles and preferences.
The guideline also addresses the risk factors associated with race and suggests that treatment for African Americans should be more intense (e.g., favour two drug therapy), for example, in recognition of their more difficult to control hypertension. In addition, the guideline addresses common secondary causes of hypertension, such as primary aldosteronism, chronic kidney disease, sleep apnoea and hormonal conditions.
The importance of accurate measuring
Despite being developed for the same condition, expert clinical guidelines typically vary in their recommendations depending on which research studies were considered and, more importantly, because of how the various studies were interpreted. Also, the experiences and knowledge of the expert review panel will undoubtedly influence the interpretation of data. This explains why even high quality, evidence-based guidelines examining the same body of published literature will differ in their recommendations.
Examples of this are the BP thresholds used to diagnose hypertension and also for the initiation of drug therapy. The ACC/AHA hypertension guideline recommends a threshold for the diagnosis of hypertension that is lower than used by other guideline such as the European Society of Cardiology (ESC)/European Society of Hypertension (ESH) guideline. However, in the ACC/AHA guideline ~70% of individuals initiating antihypertensive drug therapy do so after breaching the 140/90 mm Hg threshold. Thus, non-high risk hypertensives in the ACC/AHA guideline are recommended for drug therapy at the same BP threshold as in the ESC/ESH guideline, albeit without a prolonged trial of diet and lifestyle modification.
Aspects such as orthostatic, or postural hypotension, also need to be considered. This is a sudden drop in blood pressure when moving from seated to standing (1 minute) that is associated with ageing as well as selected antihypertensive drug classes and co-morbidities. Also, the vast majority of hypertensives with orthostatic hypotension do not report subjective orthostatic symptoms and most hypertensives with orthostatic symptoms do not actually have orthostatic hypotension.
Due to the above, Dr Flack highlights that it is necessary to accurately measure BP to reliably diagnose hypertension, allowing more precise assessment of its severity as well as to ensure the patient is not over-medicated in the pursuit of attempting to lower erroneously elevated BP readings. He reports that cases of masked hypertension, which is defined as normal BP reading in the office but elevated readings at home can result in a missed diagnosis of hypertension. However, this discordance between office and home BP readings is typically due to poor BP measurement technique when patients have not been trained on how to obtain accurate BP readings, rather than representing truly discordant results.
He points out that if no rigorous BP measurement protocol is used, BP readings are usually biased upwards. Nevertheless, the extra time and effort to measure BP accurately is certainly worth it.
A new approach to identifying risk
In the 2017 ACC/AHA guideline absolute cardiovascular risk was used, for the first time, to stratify individuals. Another first is that for low-risk hypertensives this guideline dissociates the BP threshold for diagnosis of hypertension (≥ 130/80 mm Hg) from the BP threshold (≥ 140/90 mm Hg) for initiation of pharmacological therapy.
Individuals in the high-risk group were either aged ≥ 65 years, had co-morbidities such as diabetes, chronic kidney disease, known cardiovascular disease or had a 10-year estimated cardiovascular disease risk of at least 10%.
Patients who fall into the high-risk category should have pharmacological treatment started at a lower BP threshold (130/80 mm Hg) than those who are lower risk, i.e. they qualify for drug treatment even if they do not reach the higher BP threshold (140/90 mm Hg). The preferred drug class(es) depends on the presence of selected co-morbidities and the intensity of initial treatment (1 or 2 drugs) depends on the magnitude of the BP elevation.
The guideline suggests that combination therapy, the use of two different hypertension drugs, should be used: 1) in people whose blood pressure is significantly (> 20/10 mm Hg) over the target on-treatment BP, 2) preferential to monotherapy in black patients, and 3) should be considered in individuals with BP ≥ 140/90 mmm Hg. The guideline discusses that although triple drug combinations are approved by the US Food and Drug Administration, there is no current indication for more than two drugs initially in drug naïve patients. Greater use of effective combination drug therapy will improve hypertension control rates. The most commonly used and effective two drug combinations are either an ACE inhibitor or ARB used in combination with a thiazide or thiazide-like diuretic or calcium antagonist. The ACC/AHA guideline also includes guidance about which drugs should be used if patients have co-morbidities, and recommends four classes of drugs as first line options – thiazide diuretics, angiotensin receptor blockers, angiotensin converting enzyme inhibitors, and calcium antagonists.
Lifestyle modifications should also be recommended for all patients with elevated BP (120 – 129/<80 mm Hg) or hypertension (> 130/80 mm Hg), irrespective of whether they are taking medications or not.
What is distinctive about the 2017 ACC/AHA hypertension guideline apart from other guidance is that it expanded the number of hypertensives eligible for pharmacological treatment and recommended a lower on-treatment BP target even for low-risk hypertensives based on a very reasonable interpretation and synthesis of the vast hypertension database.
Dr Flack concludes that the 2017 guidelines provide comprehensive guidance to practitioners to aid in the diagnosis, management and monitoring of hypertension. However, he explains that the guideline will need to be locally tailored into easy to use forms for use by practitioners and their teams to improve the care of their patients with hypertension.
- Flack, J. M., & Adekola, B. (2020). Blood pressure and the new ACC/AHA hypertension guidelines. Trends in Cardiovascular Medicine, 30(3), 160–164. https://doi.org/10.1016/j.tcm.2019.05.003
- Whelton, P. K., et al. (2018). Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension (Dallas, Tex.: 1979), 71(6), e13–e115. https://doi.org/10.1161/HYP.0000000000000065
- World Health Organization (2016) Global NCD target.
https://www.who.int/beat-ncds/take-action/policy-brief-reduce-high-blood-pressure.pdf [Accessed June 26 2021].
A professor in Internal Medicine and clinical hypertension specialist, Dr John Flack’s clinical activities and research explores optimal approaches for the control of complex hypertension.
Dr John Flack is an Internal Medicine specialist as well as a practicing Hypertension Specialist who also is Chair of the department of Medicine at Southern Illinois University.
Dr Adekola is a board certified Nephrologist and Hypertension Specialist at the department of Medicine at Southern Illinois University.