Cardiovascular Journal of Africa: Vol 30 No 3 (May/June 2019)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 3, May/June 2019

AFRICA

185

130/80 mmHg. The current SAHS definition of hypertension is

shown in Table 3 for comparison.

What was the rationale for the changes?

It is reasonable to assume that the recommendations were based

largely on the SPRINT study.

In brief, the SPRINT study enrolled

hypertensive patients over 50 years, with a systolic BP between 130

and 180 mmHg, with clinical or subclinical CV disease without

diabetes or stroke, but including those with chronic kidney

disease. Patients were randomised to intense control of systolic

BP (

120 mmHg) versus usual control (

140 mmHg). The study

was stopped prematurely because in the intensive arm there was

significant reduction in major adverse CV events (MACE) [hazard

ratio (HR) 0.75 (0.64–0.89),

0.001], CV mortality [HR 0.57

(0.38–0.85),

0.005] and heart failure [HR 0.62 (0.45–0.84),

0.002].

As a result of the study, the new Canadian hypertension

guidelines recommended a target of

120/80 mmHg in those

patients meeting the SPRINT entry criteria.

However the

AHA/ACC recommended a target BP of

130/80 mmHg for

all hypertensives.

The slightly higher target was presumably

recommended as analysis of the results of SPRINT showed that

in weighing risks versus benefits, the best results were achieved at

a systolic BP of

132 mmHg.

What are the controversies?

Several controversies arose from these recommendations, but

central to this was the redefinition of hypertension and the

resultant changes in target. Although there is a clear relationship

between increasing BP and CV events, starting at 115/75 mmHg,

the definition of hypertension has been generally defined as

140/90 mmHg, based on a pragmatic definition where diagnosis

and treatment do more good than harm, as proposed by Rose.

The European hypertension guidelines of 2018 have not changed

the definition of hypertension,

and it is difficult to understand

how two authoritative guideline committees come to different

recommendations based on the same evidence.

There is currently no evidence to support treating patients

with systolic BP levels between 130 and 140 mmHg, without

additional markers of CV risk, to a target BP

130/80 mmHg.

This is highlighted in the ACC/AHA guidelines where there

was only a recommendation to treat low-risk hypertensives

pharmacologically at systolic BP levels between 130 and 140

mmHg.

The evidence from other studies involving high-risk patients

with previous stroke and diabetes (excluded from SPRINT)

was also not conclusive in finding benefit from intensive BP

control. In the ACCORD study, which was a similar study

to SPRINT and performed in high-risk patients with type 2

diabetes, intensive control of systolic BP (

120 vs

140 mmHg)

did not result in a significant reduction in MACE.

Therefore,

in contrast to the ACC/AHA guidelines, the American Diabetes

Association recommendation for the definition of hypertension

for diabetics remains unchanged at 140/90 mmHg, and most

patients with diabetes and hypertension should be treated to

a systolic BP goal of

140 mmHg and a diastolic BP goal of

90 mmHg. Lower systolic and diastolic blood pressure targets,

such as 130/80 mmHg, may be appropriate for individuals at

high risk of CV disease, if they can be achieved without undue

treatment burden.

Similarly, in the SPS3 study done in patients

with hypertensive stroke, intensive BP control did not meet the

primary end-point of reduction in stroke events, although there

was a significant reduction in incidence of haemorrhagic stroke.

Another controversy arising fromSPRINTwas the way the BP

was measured. This was done by automated devices and a mean

of three readings were taken that were generally unobserved. This

method of BP measurement is termed automated office blood

pressure (AOBP). It more accurately reflects daytime ambulatory

BP by reducing the white-coat effect and correlates better with

target-organ damage than conventional office BP.

Office systolic

BP in the standard clinical setting is on average 15 mmHg higher

than AOBP, presumably due to reduction in white-coat effect

and inaccuracies in standard office measurements.

Although

the improvement in accuracy of BP measurement in clinical

trials and practice is desirable, the lack of standardisation of

measurement between trials complicates the recommendations

ont targets and definitions of hypertension.

Important adverse events were reported in SPRINT and

ACCORD in the intensive group, mostly attributed to too-low

Table 2. BP targets according to the AHA/ACC hypertension guidelines (adapted reference 8)

Level of recommendation BP goal for patients with hypertension

For adults with confirmed hypertension and known CVD or ASCVD event risk

10%, a BP target

130/80 mmHg is recommended

IIb

For adults with confirmed hypertension without additional markers of increased CVD risk, a BP target

130/80 mmHg may be reasonable

CVD, cardiovascular disease; ASCVD, atherosclerotic cardiovascular disease.

Table 3. Current SAHS definition of hypertension (adapted reference 1)

BP category*

SBP

DBP

Normal

120

and

Optimal

120–129

and

High normal

130–139

80–89

Hypertension

Grade 1

140–159

90–99

Grade 2

160–179

100–109

Grade 3

≥ 180

≥ 110

Isolated systolic

≥ 140

and

*Individuals with SBP and DBP in two categories should be designated to

higher BP based on two or more careful readings obtained on two or more

occasions.

Table 1. Classification of hypertension according to the AHA/ACC

hypertension guidelines (adapted reference 8)