Cardiovascular Journal of Africa: Vol 30 No 2 (March/April 2019)

5 / 74

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 2, March/April 2019 AFRICA 71
Target blood pressure: a South African perspective
Andrew Black, Andrew G Parrish, Brian Rayner, Trudy D Leong, Vuyokazi Mpongoshe
Cardiovascular disease is the leading cause of death globally,1
with hypertension shown to be a major preventable cause among
African communities.2-5 South Africa had the highest prevalence
(42–54%) of hypertension in a 2017 cross-sectional study of
sub-Saharan African countries.6 Decreasing blood pressure (BP)
through lifestyle changes and antihypertensive agents reduces
premature morbidity and mortality rates,7 and should be a focal
strategy for improving patient outcomes.
The American College of Cardiology (ACC)/American Heart
Association (AHA) hypertension guidelines8 and the European
Society of Cardiology (ESC)/European Society of Hypertension
(ESH) guidelines were updated in 2017 and 2018, respectively.
These guidelines differ with regard to the recommended BP
treatment threshold, the former recommending 130/80 mmHg
and the latter defines conventional office hypertension as ≥
140/90 mmHg. The lower threshold in the US guideline was
largely based on the SPRINT trial that showed improvement in
both cardiovascular and mortality endpoints in the intensively
controlled group.9
A detailed review of SPRINT will not be provided, but
key issues were the elderly population, the choice of method
for measuring BP (likely to generate values between 10 and 20
mmHg lower than with older methods10) and the premature
discontinuation of the study, which some authors argue may
have led to an overestimation of effect size. It should also be
noted that more than 90% of participants were already on
antihypertensive medication, with a mean systolic BP of 139.7
mmHg, and had evidence of an increased cardiovascular risk at
enrolment.
Participants in the intensive arm required 25% more
monitoring visits to titrate the medication and the use of
an average of one additional antihypertensive medication,
compared to the standard-treatment group. Despite this, less
than 50% of patients in the intensive-treatment arm achieved a
systolic BP < 120 mmHg.
The major benefits seen in SPRINT were a decrease in
incidence of cardiovascular and all-cause mortality and heart
failure. The possibility that increased contact with medical
services, seen in the intensive-treatment group, may have had a
positive effect in decreasing mortality rates cannot be discounted.
The increased use of diuretics in the intensive-treatment group
and their withdrawal in the standard-treatment group may have
altered the frequency of cardiac failure, one of the major drivers
of CV events in the study, by either masking or unmasking
congestive symptoms.
Any possible benefits need to be balanced with potential
harm, particularly in a setting where it may not be possible to
closely monitor or treat serious adverse events. Syncopal events
and incidence of postural hypotension were significantly higher
in the intensive-treatment group; both these adverse events are
unpleasant and may predispose to non-adherence. Of particular
concern is that among the participants who did not have chronic
kidney disease at baseline, a decrease in the estimated glomerular
filtration rate of 30% or more to a value of less than 60 ml/
min/1.73 m2 occurred more frequently in the intensive-treatment
group than in the standard-treatment group (1.21 vs 0.35% per
year).9
In SPRINT, these adverse events were found after BP
reductions of less than 20 mmHg (mean starting systolic
pressure 139.7 mmHg), and greater absolute reductions may be
associated with more adverse events.11 This is also demonstrated
in the meta-regression analysis performed by Thomopoulos et
al .12 For every 100 patients achieving a 10-mmHg systolic BP
reduction over five years, it was shown that there will be three
fewer episodes of a combination of stroke, ischaemic heart
disease or heart failure, and one death will be prevented. In the
same period, eight patients will need to discontinue treatment
permanently due to adverse events if the achieved systolic BP is
< 140 mmHg, and 10 patients if it is < 130 mmHg.
The hypertension debate has been very SPRINT-centric,
and cognisance needs to be taken of the results of other large
BP trials and post hoc analyses in various populations. The
analyses by Wokhulu et al.13 on participants from INVEST and
by Bohm et al. on those from ONTARGET/TRANSCEND14
showed a significant increase in mortality rate for SBP < 120
mmHg. The analysis by Okin et al. of data from LIFE11 showed
a significant increase in mortality rate for SBP < 130 mmHg. By
contrast, Lonn et al.15 did not show a benefit in treating SBP to
< 140 mmHg in patients with intermediate cardiovascular risk.
Department of Internal Medicine, Helen Joseph Hospital,
University of the Witwatersrand, Johannesburg, South Africa
Andrew Black, MB ChB, FCP, FACP
Department of Internal Medicine, Frere and Cecilia
Makiwane Hospitals, East London, South Africa
Andrew G Parrish, MB ChB, DA (SA), MMed (Med), MMedSci,
FCP (SA)
Division of Nephrology and Hypertension, University of
Cape Town, Cape Town, South Africa
Brian Rayner, MB ChB, FCP, MMed, PhD
National Department of Health, Essential Drugs
Programme, South Africa
Trudy D Leong, B Pharm, MSc Med (Pharmacotherapy), MSc (Clin
Epi),
Government Employment Medical Scheme, South Africa
Vuyokazi Mpongoshe, MB ChB, BSc, Adv Dip (Business Project
Management)
Editorial